700C to 650B: Road Bike to Dirt and Gravel Rig

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Interested in converting a 700C cyclocross or touring bike into a 650B gravel bikepacking rig? Or maybe you’re just intrigued by 650B / road plus? With the promise of dirt-friendly tires and a more supple ride, there’s plenty to like. We took an Advocate Lorax and made the switch. Find out what we learned about 650B, everything you need to know about such a conversion, and details about the specific components we selected.

With the recent flood of 650B gravel/adventure bikes coming to market, and 47-50mm road plus tires surging in popularity, you might be interested in purchasing a new 650B rig or converting the 700C bike you already have. Otherwise, you might just be trying to wade through all the marketing jargon to see if 650B is a good fit for you. In this guide, you’ll find all the facts and figures you need to know about 650B, learn whether your 700C bike is suitable for a conversion, and get some ideas about how to take on such a project. First, let’s start with the basics.

700C to 650b conversion, Advocate Lorax, compass tires

What is 650B?

In short, it’s a wheel size in between 26” and 29”. To clarify, there are three commonly used wheel sizes in the conventional bike market—26”, 27.5”, and 29”—that are based on 559, 584, and 622mm bead seat diameters, respectively. Just as a 700C wheel is the same diameter as a 29” (29er) wheel, 650B shares the exact same rim diameter as 27.5”.

As it happened, the bike industry came to describe and market road category (drop-bar) products in “C” and millimeters, and mountain bike products in inches. Well, kind of. It’s not an altogether exact science, since the 700 and 650 numbers don’t translate. 27.5”/650B rims have a bead seat diameter of 584mm, and 29”/700C rims have a bead seat diameter of 622mm. Adding to the confusion, and counter to what the industry might lead you to believe, 650B is nothing new. It’s actually been around for quite some time (see boxout below).

A Brief History of Tire Sizes

Why are rims with a 622mm bead seat called 700C and ones with a 584mm bead seat called 650B? Originally, there were 700A, 700B, and 700C rims and tires, all of which had an outer tire diameter of 700mm, with A being the skinniest (and fastest) and C tires being the thickest. So, A had the largest rim (bead seat) and C had the smallest. Eventually, the C permutation won out, and people altered the outer diameter by mounting different tire sizes on a 700C rim.

A similar scene played out with 650 rims. There were several variations on the rim diameter and ‘B’ triumphed, although Schwinn adopted 650C for their cruiser bikes for a while. Back in the 1930s, the “650B Balloon,” also known as 26 x 1 1/2″, became popular in France for randonneurs, loaded touring bikes, and tandems. However, the 650B size never caught on in the United States, and its popularity waned in France alongside the growth and adoption of the mountain bike.

Much later, circa 2007, with Kirk Pacenti on the front lines, 27.5” mountain bike wheels suddenly hit the scene. Years after, in 2013, it took off when almost a dozen bike companies released 27.5” mountain bikes touted to have the perfect blend of a 29er’s rollover with the nimble playfulness of a classic 26” wheel. Parts manufacturers followed suit. Today, 27.5” wheels have all but taken over.

All the while, in the expanding all-road and gravel scene, there has been a dedicated 650B fanbase who have been diligently working to restore it to its former glory. Driven by aficionados of the classic French style bikes and gravel brevet enthusiasts, tire options started popping up. With new 650B bikes popping up monthly, now seems to be its time.

Most of the bikes now coming out in this genre are either road plus / all-road, or more of an aggressive monstercross style. The latter usually means 27.5 x 2.1” semi-slick tires or bigger XC rubber, like the WTB Nano on the Bombtrack Hook EXT-C. And road plus often refers to 47-50mm tires that are generally devoid of tread aside from small side knobs, like the WTB Byway, or have a slight texture like the tire that started it all, the Compass Switchback Hill 48mm.

  • WTB Byway 650B
  • Compass Switchback Hill 650B

Appropriately, the Switchback Hill was named after a pass on the 360-mile Oregon Outback gravel route, where the gravel is quite loose. The Switchback Hill was developed as an all-roads tire to add floatation and provide speed and security when the going gets rough. In addition, 30% of the Oregon Outback route is on pavement, so this tire style is meant to roll as fast and grip as well as a good road tire would, offering of the best of both worlds. We asked Jan Heine, 650B connoisseur and founder of Compass Bicycle, how he decided on the Switchback Hill’s 48mm width, a size many other companies are now following.

According to Jan, “We were thinking about how wide a tire can fit between a set of ‘road’ cranks with narrow Q-factor. Without a huge amount of trickery, like the dropped chainstay that Open and 3T use, you end up with a 650B x 48. So we learned that this was a good size. We are really happy that other companies have followed suit and offered tires in this size, especially at the OEM level. The manufacturing costs of high-end tires like our Compass tires are too high to make suitable for production bikes, but now that others offer ‘OEM’-spec tires in this width, we are seeing many production bikes designed around wide 650B tires. That is really exciting!”

Why 650B?

Before we dive into the details about converting a bike to 650B, let’s talk a little bit about the platform and who 650B is best suited for. The main reason most folks consider 650B is to have bigger, wider tires—usually 47mm-53mm (around 2.1”)—on a drop-bar bike that would normally be fitted with much narrower tires. The benefits are fairly obvious. Wider tires offer more floatation, a more supple ride, and are all around better suited to dirt and gravel surfaces. They can also be just as fast as road tires, as proven by Jan Heine in Bicycle Quarterly.

Why not just slap a pair of chunky 700C x 45mm tires on your ‘cross bike and call it a day? Unfortunately, most 700C drop bar cyclocross, gravel, and touring bikes have clearance restrictions well under 45mm. In most cases, these limitations are based on the frame design, dictated by the chainstay/yoke configuration required to accomodate a typical 68mm bottom bracket shell and road drivetrain. Most are limited to tires under 40mm, even. But clearance restrictions aren’t the whole story.

  • 700C to 650b conversion, Advocate Lorax, compass tires
  • 700C to 650b conversion, Advocate Lorax, compass tires

Wider Tires, Same Diameter

There are a few 700C drop-bar bikes that can fit big tires. Both the Salsa Cutthroat and the Kona Sutra LTD (though in marketing terms they’re drop-bar 29ers) can fit 29 x 2.3” tires via the use of a 72mm bottom bracket shell. And there are several others that can accommodate 45mm or larger rubber. But, much of the draw of 650B is that it enables the use of wide tires while maintaining a smaller and more manageable tire diameter. For reference, the diameter of a a 650B x 47mm tire equals that of a 700x28mm tire.

So, why should this matter? For many riders, the large diameter of a 700C x 45mm or 29 x 2.1” tire might feel too big. Not always, but sometimes. And, for many riders under 5 ½ feet tall, the smaller diameter of 650B might feel more comfortable. In addition, reducing the rim diameter allows a bike to maintain better handling characteristics and react more quickly to rider input. With that said, 650B works for taller riders as well.

For shorter riders, the use of 650B has much to do with bike fit. Several 700C bike models, such as the Marin Four Corners, switch to 650B for their smaller sizes to maintain proportional geometry. Case in point, the Surly Straggler is offered in either 700C or 650B in sizes 52-58cm, 700C only in 60 and 62mm, and 650B only in 38, 42, 46, and 50cm models. As implied, for 52-58cm sizes, it’s often a matter of taste. But, even so, since the 700C Straggler is designed for 42mm tires, the 650B version has a different geometry.

If you are simply looking to swap tires on a bike, consider your bike’s geometry—the reason there used to be 700A, B, and C. If a bike was designed around 25mm tires and you manage to squeeze 2” rubber into the frame, there will be consequences. Most notably, in the bike’s standover height and toe overlap. Conversely, if a bike was designed around 700C x 45mm tires and you switch to 650B x 47mm, the bottom bracket will likely be far too low. This is why the diameter of a bike’s intended wheel and tire combo should be scrutinized. 650B tires, such as the popular 47mm Byway or 48mm Switchback Hill, will have a diameter of about 678-679mm, approximately the same as a 700C x 28mm wheel/tire combo. Here are five useful equivalents:

700C x 23mm = 668mm = 650B x 42mm
700C x 28mm = 678mm = 650B x 47mm
700C x 32mm = 686mm = 650B x 50mm
700C x 35mm = 692mm = 27.5 x 2.1”
700C x 38mm = 698mm = 27.5 x 2.25”

Generally speaking, the main reason folks are making the switch to 650B is to have wider tires, but that’s just one part of the equation. Consider these additional reasons…

Maintain a Comfy Gearing

Gearing is another factor that’s directly affected by wheel and tire size. As tire size goes up, so does gearing. When comparing a 650B rig with 2” tires and a 700C bike with 2” tires, the latter will require a lower granny gear to climb the same hill in the same cadence while loaded down with bikepacking equipment. Not only is going to the smaller 650B diameter with large volume tires good for keeping low gearing, but it also keeps gearing roughly the same as what road riders are used to. More air and rubber, same gear ratios. That makes the naming convention behind Compass’ Switchback Hill tires click, right?

Toe Clearance, Low Overlap

Toe overlap is a term for shoe interference from the front tire, usually experienced at slower speeds when pedaling technical terrain or during maneuvers that require tight turning. Most drop-bar bikes with bigger tires will have a little toe overlap, but there is definitely a point at which it can become a burden. That’s where 650B saves the day. With the same diameter as a 700C x 28mm tire, a 650B x 48mm tire can provide all the goods without risking excessive toe overlap.

Bonus Round: Hidden Perks

There are a few other inherent advantages to moving from 700C to 650B. For one, shorter spoke lengths make stronger wheels. By virtue, smaller wheels should be stiffer, too, which means more responsive pedaling. In addition, smaller rims and wheels mean less metal was used to make the rims and spokes, which should translate to a lighter wheel. Smaller wheels and tires free up more room for seat bags and handlebar bags too. And, last but not least, they make packing a bike easier for travel or shipping.

700C to 650b conversion, Advocate Lorax, compass tires

Converting a 700C Bike to 650B

Before the current trend of new 650B production drop-bar bikes, 650B was largely relegated to small frame builders, randonneuring enthusiasts, tinkerers, and folks interested in converting older road bikes to get some of the big tire secret sauce. In the following section, we’ll look at why the ideal 700C to 650B conversion involves a bike built around skinner 700C wheels that normally fit less than 40mm tires, like a touring or cyclocross frame. The most common and appropriate 650B conversions involve a 700C bike built around 25-30mm tires.

For this project, we used a size medium Advocate Lorax, a bike designed around 700C x 38mm tires, and an already adept gravel bike. But the Lorax maxes out at 40mm tires in 700C and more volume was needed. Even so, we knew going into it that this wasn’t the perfect bike for road plus tires, but it would work with shorter cranks. This leads us to the first factor to consider before tackling a 650B conversion: the bike’s intended tire size. As mentioned, 650B x 47/48mm tires usually have a similar diameter to a 700c x 28/30mm wheel/tire combo. If your bike was designed around such a tire, or a 32-35mm tire, 650B conversion might be appropriate. And, even if you have a bike designed around 700C x 35-42mm tires, it is still a possibility, but bottom bracket height and tire width clearance might be issues. Either way, there are a few preliminary details to evaluate:

PAUL Klamper Brakes

Disc Brakes

Brakes are most hardline obstacle when switching from 700C (622mm) to 650B (584mm) wheels. If your bike has disc brakes, you’re golden. If not, you’ll have to decide whether it’s worth the trouble. 650B rims have a radius that’s 19mm smaller than that of 700C. So, if you’re running non-disc brakes, you’ll need to have your brake mounts moved or find brake calipers with a really long reach. Just how long of a reach you’ll need – and whether you can even use your existing centermount or post mounts – will depend on the dimensions of your specific frame and fork. To establish the required brake reach, measure the reach with the original 700C wheels and add 19mm. There are rumors that it’s sometimes possible with BMX-style and centerpull calipers and, but that’s beyond the scope of this article.

650B Tire Clearance, 700C to 650B

Tire Clearance

If brakes aren’t an issue, the next most obvious consideration is whether or not your bike has the proper clearance for big 650B tires. The favorable 650B x 47/48mm tires, made popular by the 48mm Compass Switchback Hill and 47mm WTB Byway, have a similar tire diameter to 700×28 wheels and tires. So, chainstay length isn’t usually the issue. It’s the width that can be a challenge. The widest point in a 650B x 47-48mm tire is about 325mm from center of the rear axle. So if you measure that distance on your stay, from the rear axle, you should have over 58mm of room (in our opinion) for a 47/48mm 650B tire. The Lorax has 63mm, which left a comfortable 8mm on each side of the tire as breathing room.

700C to 650b conversion, Advocate Lorax, compass tires

Bottom Bracket Drop

Now that we’ve covered tire diameter, it’s easy to see how to match the intended vertical stance of a bike. But, what about the actual numbers? What makes a BB height short enough that pedal strikes and cornering will be an issue? To answer that, let’s look at the bottom bracket drop (distance of center of BB shell from axle plane) on a few recently released 650B-specific bikes. The Bombtrack Audax has a 65mm BB drop (L), Surly’s Midnight Special shows 65mm, Chumba’s Terlingua has about 66mm, and the Masi Speciale Randonneur 650B has 70mm. All four are specced with 47mm WTB Byways. Moving to the MTB side of the spectrum, the Norco Search XR (70mm BB drop), the Salsa Journeyman (72mm), and the large Bombtrack Hook EXT-C (67mm) are all specced with 27.5 x 2.1” tires.

One thing to remember with wider tires is that they have more tire drop—more deflection under load. According to Jan Heine, “You really need to factor the BB height with about 15% tire drop. In the old days, with 20mm tires, tire drop was 3mm—not a big deal—but the Switchback Hill 48mm tire will drop about 7mm when the rider is on the bike!” Jan also suggested that tire drop is independent of rider weight, and that for this type of tire, it’s appropriate for air pressure to be set at about 15% tire drop, almost like suspension sag. Heavier riders use higher pressure, lighter riders lower pressure.

Now, what’s the proper BB drop for 47-48mm road plus tires? Between 63 and 70mm, it seems. According to Jan, “For a 650B x 48mm Switchback Hill, you’ll need a 70mm bottom bracket drop to achieve the ‘road standard’ BB height of 265mm. With a 650B x 42mm tires, you’ll want a bit less BB drop—ideal would be 63mm.” The Lorax has a 75mm BB drop, which is a little low. But with 170mm cranks it seems OK after a few rides. we may end up putting 50mm tires on it to beef it up a hair though.

And for 2.1-2.2” MTB tires? 65-75mm. Anything lower might start being risky when it comes to pedal clearance. Of course, some of this can be mitigated with shorter cranks, such as 165 or 170mm arms. Your preferences may differ depending on intended terrain. I personally think between 65-67mm is ideal, with 170mm crank arms, as this provides adequate clearance for riding on some extra chunky bits.

Another reference is WTB’s list of compatible frames that will work with their Byway road plus tires. However, this is by no means a complete list.

The Cast of Components

Given its modular dropout system, the Advocate Lorax is a versatile bike to tinker with for a project such as this. Switching the modular dropouts from a 135mm/QR to a 142 x 12mm thru-axle enabled a stiffer and modernized rear end. We handpicked all the components to create a 650B bike specifically for gravel bikepacking. Here they are:

Hunt AdventureSport Disc

Hunt has a lot of great wheels in tons of widths and configurations, all very reasonably priced and designed to withstand adventure. The AdventureSport Disc, as used here, are a good option for 42-48mm tires. They feature a 20mm inner width, tubeless ready rim with a hookless bead, and an asymmetric spoke design for toughness and durability. In addition, they are extremely versatile. Each wheelset includes axle adapters to convert to QR or thru-bolt in 12/15/9mm axle diameters (front), and 12×142, 12×135, 10×135 in the rear. They also include tubeless tape and valves, spare spokes, and a spoke key, all for about $445 USD. Hunt also has wider wheelsets that might be a little better for 48-2.2” tires. Check out their 24mm IW AdventureCarbon wheels, affordable 29mm IW TrailWide, and their Dynamo specific wheels.

  • Hunt 650B AdventureSport Disc Wheels, Bikepacking
  • Hunt 650B AdventureSport Disc Wheels, Bikepacking
  • Hunt 650B AdventureSport Disc Wheels, Bikepacking
  • Hunt 650B AdventureSport Disc Wheels, Bikepacking
  • Hunt 650B AdventureSport Disc Wheels, Bikepacking

SRAM Rival Drivetrain

In our opinion, SRAM Rival is the best bang for the buck when it comes to modern road drivetrains. It’s versatile, and you can usually get a Rival 1 shifter/derailleur/crankset for a little over $300. The derailleur and shifter are extremely solid, and it gives you a lot of options. For starters, the Rival 1 (1x) is a direct mount crankset, so you can easily switch the chainring to dial in gearing.

  • SRAM Rival 1 drivetrain
  • SRAM Rival 1 drivetrain
  • SRAM Rival 1, 700C to 650b conversion, Advocate Lorax, compass tires
  • SRAM Rival 1 drivetrain
  • Porcelain Rocket Nigel Handlebar Bag, waterproof

We added a Wolf Tooth CAMO system to facilitate easily swapping out chainrings for different rides. And, the Rival 22 (2x) offers a decent 50/32 ring combo, although 46/30 would be a little better for loaded bikepacking. In addition, the XG-1150 full-pin steel cassette is super solid. And, if a 42T big cog isn’t enough, the Rival derailleur also works with a 46T cassette.

eThirteen TSRR Cassette

eThirteen TRSr Cassette

While many folks will opt for a 2x drivetrain, it’s hard to disregard the simplicity of a 1x. The new eThirteen TRSr 9-46 cassette is one of the widest range 11-speed cassettes out there. With a 511% gear range, it’s even wider than 1×12 Eagle. In addition, 46T is about as big as a Rival derailleur can go. At $350, it’s certainly not cheap, but you can get the TRS+ for less than $250 with the same range.

PAUL Klamper Brakes

PAUL Klamper Brakes

BB7s aren’t the only mechanical disc brakes on the market. After using the Paul Klamper on trips through Uganda, Rwanda, the US, and, recently, the Republic of Georgia, we are pretty confident in their durability. And, aside from their stylish design, adjustments on the Klamper are the easiest of all the mechanical disc brakes we’ve tried. Plus, they’re made in Chico, California, by a great company. We got a pair of short-pull black and orange versions for this build.

Fyxation Sparta All Road Fork

There are a few carbon replacement forks out there now, but the Fyxation Sparta is available at the right price and with all the right features. The bottle mounts are a big selling point, but it also has the right measurements—400mm axle to crown, 45mm rake, and options for 100 x 12 or 15mm bolt-in thru-axles. The Sparta also has provisions for fender mounts, internal cable routing, and room for 650b x 50 road plus tires. For $299, it seems like a great choice for a gravel bike fork. It’s stiff and does a good job soaking up the chatter, too.

  • Fyxation Sparta All road Fork, gravel, bikepacking, 650B
  • Fyxation Sparta All road Fork, gravel, bikepacking, 650B
  • Fyxation Sparta All road Fork, gravel, bikepacking, 650B
  • Fyxation Sparta All road Fork, gravel, bikepacking, 650B
  • Fyxation Sparta All road Fork, gravel, bikepacking, 650B

Other impressive bits and bobs include a Brooks Cambium C17 All Weather saddle, Brooks Cambium bar tape, PAUL BoxCar stem, PAUL Tall and Handsome seatpost, and Salsa Cowchipper handlebars. Here’s the full build kit:

  • Frame Advocate Lorax (M)
  • Fork Fyxation Sparta All-road
  • Shifter/Derailleur SRAM Rival 1
  • Crankset Rival 1 38T
  • Cassette eThirteen TRSr 9-46
  • Rims Mason x Hunt AdventureSport 24mm deep | 25mm wide (external)
  • Hubs Mason x Hunt 4Season Disc (142 x 12mm r / 100 x 15mm F)
  • Brakes PAUL Klamper (short pull)
  • Handlebars Salsa Cowchipper 144cm
  • Bar Tape Brooks Cambium Rubber (Natural)
  • Stem PAUL Boxcar 50mm
  • Seatpost PAUL Tall & Handsome
  • Saddle Brooks C17 All Weather Carved Black
  • Tires WTB Byway / Compass Switchback Hill
  • PAUL Tall and Handsome Seat Post
  • Brooks C17 All-Weather saddle, bikepacking
  • PAUL Boxcar Stem
  • 700C to 650b conversion, Advocate Lorax, compass tires
  • 700C to 650b conversion, Advocate Lorax, compass tires

Have something to add about your own experience converting from 700C to 650B? Leave a comment below. Also, stay tuned for more coverage on the Compass Switchback Hill and WTB Byway tires.

67 Comments
  • nishars

    Really loved reading through the parts you speced on the bike and your reasons behind them. Solid choices all around.
    A tan colored Brooks would complete this build with matching tires and bar tape.

    Next up, I would like to see this bike fully kitted with bikepacking bags and how it fits on this bike.

  • Thanks!! Yeah, the natural Cambium version would have been nice. But, the ‘All Weather’ version only comes in black, red or dark blue.

    I’ll add bikepacking setup pics when we get them….

  • Erik Bakke

    Nice setup.
    I get the mechanical brakes as “field serviceable”, but given extra weight and rarely an issue with hydraulics… well to each his own.
    The fully housed shifter cable is smart… but the routing could be a little more elegant.
    Are the non-horizontal drops on the actually comfortable for riding long distances? My hands always feel better when they are horizontal, or at least close.

  • Chris Leydig

    Great article, very informative.

    I’ve been thinking about a bike build like this for some time that could be my ‘fast’ road bike, with a 650b plus wheelset for kickers. My problem has been finding a frame that is built around 700c x 28-32, that has clearance for 650b x 45-50. The frame material being preferably ti. Any pointers? I saw the 3T exploro and the Open UP cycles, beautiful looking machines but not a fan of the idea of carbon for a bike to go the distance.

  • Chris Tsaki

    Very nice article!

    i will leave this one here :p for the Sequoia owners. https://www.instagram.com/p/BhzQRaphW_u/
    As answered in the comments its a 650b 2.1 in the back and a 650b 2.3 in the front. I own one and i think that the front should be ok. really wondering about the clearance on the back though. How little is actually too little clearance?

  • Thanks. Yeah, most of the time I prefer hydros with drops, but I do love the Klampers. Very easy to service, adjust, etc. And they have proven bombproof.

    Yeah, I admit the cable routing is sloppy (and temporary—zip-tied until I get some stainless cable straps).

    I, and Gin (who’s riding this bike), prefer flared drops. The upward angle is her personal preference.

  • Scott S

    Is there any chance of you switching to a 700c/29 to compare how the same frame handles with different wheel size as the sole change. It would be assumed that you would using a 32mm or plus width over a 28, which will change the numbers slightly. Would it be possible to change only the tires/wheels depending on the terrain?

  • Thanks Chris. I can’t think of any Ti options off the top of my head other than the UK Tripster ATR which fits 27.5 x 2.0″. If any more come to me, I’ll certainly add to this reply. For steel bikes, I really like the looks of the Chumba Terlingua, which has a BB drop of 66mm and fits 27.5 x 2″ tires, and maybe 2.1s… plus they are custom made in the US.

  • Thanks. As far as ‘how much is enough’ in the clearance department, that’s a good question which really depends on the frame material, what you’ll be riding, comfort level, whether you have a 142 x 12 thru-axle (for stiffness), etc. 8mm on either side on the Lorax seems pretty good, IMO. I think I could go up to a 50nmm tire and be pretty comfortable… Anything more would be a squeeze, I think. For one, there will always be instances where mud builds up on the tires. This can destroy carbon; I’ve seen it first hand. I’ve also seen it wear down steel a little too.

  • I am not sure I follow your question, exactly. We reviewed this bike with 38mm tires (it came with those, stock). It did pretty well on a gravel and a couple bikepacking trips that it went on, but at that point it was far heavier, used a different axle plate (QR), and a entry-level 2x drivetrain, etc. So it was a completely different bike.

  • Oh, the Why Cycles R+. I’ve heard great things about that bike, and it has a 70mm bb drop, but I can’t seem to find the max clearance for 27.5… I’ll see if I can find out.

  • Dylan

    Very cool. I’m designing my next rohloff build to be able to go in two directions. I previously had it build into a 29+ rim (east arc+ i40) for bikepacking on my Surly ECR, but that rotational weight was killing me. So I’m building it up into a 27.5+ carbon rim (Nextie premium 40) with an internal width of 34mm shedding an insane 270g off my rim weight alone!! With the i34 rim I’ll be able to use it on my hardtail bikepacking rig with 2.8 tires, and I’ll be able to throw it on a pavement/gravel/touring bike with 2.2 slicks…

  • Chris Leydig

    Regarding the Why Cycles R+ though, wouldn’t you be a little concerned about the BB drop (70mm) when switching to a 700c x 28? Considering its designed around 700 x 45c, seems that you’d lower the bike significantly. The primary goal on this bike is fast road endurance (for once in my life). Midnight special in Ti perhaps? Maybe I need to look the custom route but it seems there are more options coming to market.

  • That’s a great strategy… IW 34mm is a very versatile rim width.

  • Mark

    I did something similar with a Salsa Vaya stainless travel frame. Currently running the Switchback Hill tires on some leftover DT Swiss Spline 27.5 wheels & TRP Sprye brakes. I kept the 2x drivetrain, but am using SRAM carbon cranks with 46t & 33t 110 BCD chainrings from TA. I’ve thought about replacing the steel Salsa fork with that Fyxation, but haven’t pulled the trigger yet. Tire clearance in a bit close, and interestingly, it would actually be better if I could shorten the chainstay length even more because of the shape of the chainstays. No Bikepacking yet, but plenty of gravel/dirt miles, and so far, it’s a winner! https://uploads.disquscdn.com/images/b4149c6368ead923247accc2d1f408d9de1c33c5dd4b0e87ae02cbf8ebaaf3d6.jpg

  • Looks good! The Vaya is actually quite similar the Lorax, geometrically. not sure about that specific model. Same BB Drop? 75mm? If so, any issues with pedal strike?

  • Mark

    Yup, same 75mm BB drop. I’m running 170 cranks, no issues so far with pedal strikes, but I’m not riding rock gardens, and if I’m leaned over that far, I’m not pedaling!

  • Erik Bakke

    The stainless cable straps would be quite nice.

  • Yeah, that’s exactly how I felt. I would definitely prefer a 70ish mm BB drop, but I think it works with a Vaya/Lorax kind of bike as long as you use 165 or 170mm cranks and aren’t planning on riding techy bits on a regular basis.

  • Matt M.

    Just sitting quietly by myself waiting for 800c. Or is it a 32er?

  • scott s

    I’m currently building up a frame with a set of wheels for 700×32 and another set of wheels with 700×45. Would it be possible to build up a bike with 700×32 and second set of wheels with 650×48?

  • Check out the ‘Wider Tires, Same Diameter’ section above, as well as check your clearances as outlined above. That said, they are very close in tire diameter, so it should be a good match. For reference, the tire diameter of a 700C x 32mm = 686mm, which equals a 650B x 50mm tire.

  • Matt M.

    I might have Walt Works build me one. Only thing holding me back is the extremely limited tire/wheel selection.

  • Chris Tsaki

    Thanks Logan for the advice! i have had the chance to ride my Sequoia with 650b 47c terrene tires and there was enough space. I was really wondering how it should look like with the 2.1 650b. 2.0 would fit very well, i assume…
    Sunny regards from Germany!

  • Richard Smith

    Great article. So in my situation I have a Giant TCX Advanced Sx with Maxxis Rambler 40c tires (they measure 38mm on the 19″ internal rim). The same diameter then with 650b would be 2.25″, but I know I don’t have the clearance for that. I have good clearance then for the Byway or Switchback Hill, but with a bottom bracket drop 60mm (cranks are 172.5) would this be a worthwhile move or am I just going to ruin my geometry/ride feel by having a smaller diameter wheel that what the bike stocks in 700c? Like the bike in the article, I could go as big as a 50mm, but maybe I don’t need to with the bb drop I have? Any advice would be a huge help, thanks!

  • Keep me posted if it works. The Sequoia is a cool bike, and the BB drop at 65mm (on the 58cm model) is perfect for 650b.

  • Thanks! You certainly have plenty of BB height to work with. The only question I would pose is how it will affect handling. I really like how it changed the Lorax, personally. But I’ve only gotten a couple short rides on it (since technically, it’s Gin’s bike and it’s a little small for me). She seems to really like it though. And, FWIW, it was built around 38mm tires, which isn’t much of a difference for the TCX. I would also ask yourself if the bike feels too tall as is. If it does, that could certainly help answer the question. All that said, in the end, when you take into account the tire deflection, you’ll probably only be losing a centimeter in height, or maybe a hair more. If it was me, I’d want the bigger tires :). I’d be tempted to see if 2.1 Nanos would fit, personally. You might need to break out some calipers to figure it out. Also, keep in mind that you’ll want to leave plenty of room on either side of the tire since it’s a carbon frame… gravel caked mud can chew through carbon stays. you might even put some Shelter tape there for good measure…

  • Richard Smith

    Awesome. Coming from Mtn biking, I pushed it on the frame and ordered a medium even though I’m 5’7″, then changed the stem from 110 to 90mm to make it work, so that being said actually it could for sure be dropped a little lower for me I think.
    I was really wanting a 2.0-2.1 to go on, and I have read of people fitting them on this bike, but my exact hesitation is the one you bring up, carbon with that little clearance for bikepacking trips and some single track…I guess yeah I’ll have to get some calipers out and see what it would look like. Thanks again Logan

  • Swell Koerper

    Great article. From my expierence, when considering a 650b conversion, the actual width or resulting shape of a tire on a certain rim width while maxing out frame clearance is almost impossible to predict. If possible, one can ask his/her friends or LBS if they have a rim/tire combo to check before taking the plunge.

  • Dillon

    Nice-looking build. I have a question: what’s that snazzy bottle cage the bike employs? I’m looking for options to carry a 40 oz. Klean Kanteen. Thanks!

  • Konrad Królikowski

    Very inspiring. Your bike with such a big tires and flat bar looks like a rigid mtb. I built my bike on Pro Module frame set and fitted 700/43 tires. Looks like this frame lets you build nearly anything from road to rigid mtb.

  • Stephen Poole

    There’s this for starters: https://lynskeyperformance.com/gr-260-gravel-bike-free-new-ultegra-8020-hydraulic/ They can be had as framesets too, or there are custom options, including direct from China.

    Re BB drop: What suits will depend on lots of things including crank length, tyre diameter, pedal size, terrain, riding style, etc. I’m from more of a touring than MTB background, don’t pedal around corners, and use small Speedplay pedals most of the time. I also really hate high BBs on the road, and the bike with 65mm drop always seemed too high with 42-584. I’m currently dithering about 71-75mm drop, for tyres between 38-54mm.

    Those riding flats on technical terrain are likely to have a very different view about adequate BB height, but I almost never clip pedals, and for me lower always feels better; YMMV.

  • That’s the WideFoot Designs LiterCage with a Klean Canteen 40oz. more on it coming soon…

  • Nicolas

    Hi, yes indeed, I’ve put Elwood tire 650b 47c tires and it is really enjoyable! Just be careful on rocks with the lower BB …I’ve tried to fit Kenda 650b 52mm it fits on the front but not at the rear .

  • Phillip Scott

    This is a timely article and am glad to see someone else use their Sequoia for this. Mine is 58 cm. Used a 2.1 vittoria mezcal on the back and had 2 mm each side. I was worried about it in some muddy areas but sidewall and chainstays showed no rubbing. I really liked the setup. As stock, I run the 45mm riddlers and love the tires and size since I ride gravel, dirt and some rock stuff sometimes. Do need to keep at least 35 psi for my weight to not hit the rims due to rocks.

  • Alex Stark

    i was looking for something like this, i’m planing to convert my ninner rlt 9 steel to 650b, thank you very much.

  • multisportscott

    I think this is what you’re looking for Chris https://www.curvecycling.com.au/collections/frames/products/curve-gxr-kevin
    Curve are releasing a steel version which will be a touch more affordable (for me anyhoo)

  • multisportscott

    Hi Logan, thank you so much for this article, it’s brilliant. So good to read a technical article in non-technical language siting real world scenarios! I especially enjoyed you talking about BB drop.

    I have been on a quest for quite some time to find the perfect frame to allow 700c up to 45c and 650b up to 2.2. There are now oodles of options in any choice of frame material, and pretty much price point.
    What are you thoughts on q-factor and crank length for this type of bike? It seems to me that most of these bikes are being built around the narrower “road” q-factor and this is the thing that restricts the tyre width in the back. Do you have any comments on this?

    Cheers from NZ, Scott

  • Robert

    Thanks for the super informative article about exactly what I have been pondering since Surly dropped the Midnight Special. I have a Lemond Poprad that I’ve loved, though after riding plus bikes for a while, it’s been left languishing. The Poprad as 650B seems like it would be awesome, but even if it could fit road plus tires between the chainstays, the cost of the components to convert it with the solid components you list approaches the cost of the MS. So I think I’ll try maxing tires on the Poprad for the summer, and continue to research road plus options, like a Surly MS 2.0 with tubeless wheels or a BikesDirect ti copy of it.

  • Chris Leydig

    Thanks for the direction. Looks like too much clearance for my needs though. That frame says it’s optimized around 700×38-42. I’m looking for 700 x 28-32, translating to 27.5 x 45-50. I’d be looking more at this model, but with ability to fit the road plus standard as well
    https://www.curvecycling.com.au/collections/frames/products/belgie-spirit-disc-ti-road-grinder?variant=18719967493

  • Big fan of that bike. Keep me posted on how it goes…

  • Nat Smith

    The Backroad, by chance?

  • Stephen Poole

    No, it was a Soma GR, and was the first bike I’ve actively hated, in oh so many ways. The BB height was a minor annoyance compared to some of the others; let’s not go there. :-(

  • Neem

    700c to 650b tire conversion.

  • Neem

    650b to 700c tire conversion equivalent.

  • Thanks Scott!

    As far as q-factor, I definitely get the idea—our hip joints are made for walking, and walking/running keeps our feet inline—with the consensus that a less wide stance is better for your knees and hips. And, I have heard road racers can feel the affects on power and speed with a narrower Q. However, it doesn’t make any noticeable difference to me from a comfort or efficiency standpoint. I have spent much more time on MTB cranks than I have road, and even though I have had a couple instances of knee pain, I don’t think it was due to q-factor. When looking at two popular cranksets, the Race Face Aeffect and the SRAM Rival 1, they have a difference of about 23mm in q-factor. Not a huge difference in the grand scheme of things, IMO. In the end, if I were commissioning a custom bike to be built, it would have a bigger shell designed around an MTB crankset.

    Regarding crank length. I have always used 175mm crank arms as I have really long legs. But, I have been encouraged by a couple other long-legged riders to try 170mm cranks, both to improve comfort and minimize pedal strike on modern low bb trail bikes.

  • multisportscott

    So it is Chris, my mistake.
    Good luck with your search….

  • multisportscott

    Thanks Logan, I feel the same way. I have spent many many hours on both q-factors and could not tell you the difference! I have no idea about my power output on one vs the other so I don’t know if there’s a difference.
    I am also keen to experiment with shorter cranks, but it’s an expensive experiment!
    Thanks again, Scott

  • Generally speaking, I found the Road Plus to be pretty close (within 1mm) of what is marketed when they are on their appropriate rim size (23-25mm IW). I have the Compass tires on 20mm iW rims and they are about 1mm under their advertised width…

  • Yeah, components aren’t cheap. Fortunately, the Hunt wheels are pretty affordable; a wheelset and tires are the two main things. The other components would really only need to be upgraded for a ‘from scratch’ build. One way to go would be to upgrade the wheels, then plan on building up a new frame with those in the future…

  • Ian Zuckerman

    For what it’s worth, I have a 2012 Vaya Ti, and I replaced the stock steel fork with that Fyxation carbon fork a few months ago. It’s a great fork! I also changed the wheelset and shifted to through axle, and it definitely feels a lot stiff. Not sure how much weight was lost due to the fork or the wheelset, but the bike feels tons snappier and more responsive. It also seems to soak up some additional chatter over the stock fork. So far I’ve only mounted bottle cages on it for a few gravel bikepacking trips, but I hope to try a front rack on it someday for future road tours.

  • This is an interesting discussion. I am a roadie and a fan of vintage steel but might try converting my town bike (a 1972-ish Peugeot UO-18 mixte running 700 x 35 Pasela Messengers on Open Pro rims now) to 650B. Alternatively, I have an early TREK 890 urban MTB (lugged steel!) that came with 26 inch wheels and cantilever brakes that might work with 650Bs.

  • Compass has lots of other tires available that might make you happy. https://www.compasscycle.com/product-category/components/tires/

  • Matt M.

    Thanks. I’m happy with my ‘normal’ size tire selection. I’m contemplating a 36er though. Compass doesn’t have those!

  • Richard Wolf

    Nice article.
    I was a huge fan of compass tire and bought several pair and turned many others on to their tires. BUT they are not durable. Friend had one that blistered and popped on him. Several of mine would ooze sealant out of the sidewalls and when you take them off the sealant for some reason seals the tire innards to itself. Also at least with orange seal it leaves a real gummy gooey mess inside the tire which I have never had happen with other tubeless setups. I am guessing it has something to do with the very thin sidewalls and how air can permeate through them.
    They look great and roll very well but I would not trust them for a long tour or on gravel. I would also not recommend running them tubeless either.
    I understand why they roll so well and that has to do with their thin and supple sidewalls which to me is also their downfall. I had them on two bikes and one tandem but durability and peace of mind is much higher on my priority list than a fast rolling tire.
    I know they work well for a lot of people so take my review with a grain of salt.

  • Max Pasion

    Hello. Can you tell me the brand names of the large water bottle and bottle holder on this bike. Thanks

  • Widefoot liter cage and Klean Kanteen 40oz

  • Stephen Poole

    FWIW, & YMMV: I’ve tried 165, 170, 172.5, 175, 178 & 180mm cranks over the years, and now prefer to stick with 172.5 where possible. 175 are okay too, and 170 are good for fixed gear use, but I could not spin the 178 or [shudder] 180mm cranks, and didn’t like the lack of leverage with 165, or 170 to a lesser extent. However, some people don’t notice or care about crank length – lucky them!

    Q factor is similar: some like narrow, some wide, some don’t care. The only way to find out is to try different cranks for yourself. I much prefer lower Q and have a set of older Cannondale SI road cranks for the forthcoming 650b frameset, which should clear up to at least 2.1″/54mm tyres; the pre-2007 SIs have a Q of 141mm, versus 176mm for current XT. Over 155-160mm feels cumbersome to me, but some people actually prefer fatbike cranks, which are typically ~200mm.

    It’s better not to believe what anyone else suggests without verifying it for yourself(!); as with saddles there’s too much variation to make blanket recommendations useful.

  • Stephen Poole

    ^ The indents on the inside of the Sequoia chainstays are better placed for 700c than 650b. I’ve got a Vee 12 29×1.95″ on the back (actual width ~47mm) and doubt a wider 650b would fit. The 47mm tyres give much better grip and comfort on dirt than the stock tyres, and don’t seem to roll much differently on bitumen.

  • Hailey Renner

    I just snagged an Advocate Sand County frame that I was going to build up as a bikepacking/gravel adventure bike. To broaden the available terrain, I was considering using tubeless 650B tires. However, I noticed that the BB drop on the frame is 80mm. Am I thwarted by this before I even get started? Do you think 700C x 42mm tires would not leave me too lacking? I really don’t have ambitions of tackling anything more technical than the Great Divide route.

  • Hmmm. That is a low BB. What size frame? And how tall are you? Crank arm length can make a big difference. Unfortunately, Advocate doesn’t state the max tire clearances for that bike. I’d be curious it would fit 27.5 x 2.25 tires, like a Nano or something. I’d also be curious if it would fir 700c x 45 or 50mm (which would probably be my preference).

  • Thanks! And thanks for the feedback…

  • Hailey Renner

    It is a 56 frame, and I am approximately 5’10” in height. I am literally starting with just the frame, and so everything can be steered in the direction based upon wheel choice.

  • I’d definitely go with the shortest crank arms you can be comfortable with (165 if possible). is 170 your normal crank arm length? Do you know what the max clearances are on that frame?

  • Hailey Renner

    I’m primarily a road rider, so crank length is always tough to approximate. I don’t think I would be uncomfortable on 170, though, and possibly even shorter. I am e-mailing the builder now to see what the maxes are.

  • pct77

    Check out Mason Cycles. They build the Bokeh. Flipping amazing bike. Alu or Ti. https://masoncycles.cc/shop/categories/bokeh-bikes