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Fancy something a bit different? With smaller rims and fat tyres, 650B bikes combine comfort, speed and versatility

With fatter tyres on smaller wheels, the 650B standard gives the same rolling size as regular 700C wheels with more cushion and grip. Should you consider a bike with this reborn wheel spec?

What is 650B?

This is a wheel size with smaller rims than the 700C road bike standard, but larger than the 26-inch size that was the standard for mountain bikes until a few years ago. Because the rims are smaller, fitting 650B wheels into road and gravel bikes that usually take 700C wheels allows the use of fatter tyres with little or no alteration to the frame design, assuming you have disc brakes.

There used to be loads of French wheel sizes, designated by the rolling diameter of the tyre in millimetres, and a letter. The road bike standard 700C is one of these sizes; it originally had quite fat tyres that bulked things out to a rolling diameter of 700mm.

Wheel size designations are a proper omnishambles. The only way to be sure a tyre will fit a particular rim is to look at the size of the bead seat, the part of the rim where the tyre fits when inflated. Your 700C wheels have a bead seat diameter of 622mm; for 650B it's 584mm.

The 650B size was popular with French touring cyclists back in the 60s, and has been brought back from the brink of extinction by the mountain bike industry. It has pretty much replaced the original mountain bike 26-inch wheels, which have a bead seat diameter of 559mm. Also referred to as 27.5in, the wheel size is now found on bikes from entry-level hardtails to downhill bikes.

Hallett 650b - tyre

But 650B is no longer just on mountain bikes. Road bike manufacturers from small independent frame builders like Hallett Handbuilt Cycles to mainstream brands like Cannondale have adopted it for all-purpose and gravel bikes.

The combination of a 650B wheel's 584mm rim and a tyre width of between 30 and 50mm gives about the same overall wheel size as a regular 700C rim and 25mm tyre, so the rolling speed and handling characteristics will be similar to a regular road bike.

- Trend spotting: Why you need to switch to wider tyres

Benefits include additional cushioning from the bigger volume of air, providing a smoother ride, and a larger contact patch which boosts traction, ideal for mixed terrain and slippery roads.

Do we need a new wheel size?

There has been a move to wider tyres on endurance and sportives bikes over the past few years, with bikes like the Cannondale Synapse and Giant Defy, which both cater for up to 28mm tyres, proving incredibly popular with cyclists that want a bit of extra comfort.

- Buyer's guide: sportive and endurance road bikes + 15 of the Best

Even professional road race cyclists, once wedded to skinny 22 and 23mm tyres, are now switching to 25mm and 26mm tyres as standard. But it's arguably cyclists seeking comfort, especially with road conditions deteriorating due to lack of maintenance, that have been pushing manufacturers to develop bikes with space for wider tyres.

Cannondale Slate 5

The adoption of wider tyres has been swift. With many cyclists cottoning onto the benefits of wider tyres, many are seeking bikes capable of taking even wider tyres. A mere 28mm just doesn't cut it anymore. The latest crop of gravel and adventure bikes massively increase clearance over the endurance bikes, accepting tyre widths between 30 and 50mm.

- Buyer’s guide to gravel and adventure bikes plus 13 of the best

One significant benefit of 650B is to do with geometry. A 42mm tyre on a 650B rim provides about the same outside diameter as a 23mm tyre on a 700C wheel, so you can fit much wider tyres to the bike without requiring any drastic changes to the geometry of the frame and fork.

A bigger tyre on a 700C rim requires changes to the frame and geometry. The chainstays need to be longer, and with it the wheelbase and the fork needs to be taller. This can impact the handling of the bike and takes it further away from the responsiveness and agility that is the hallmark of a road bike.

Why now?

Panaracer tyres 2016 - 5.jpg

Wider tyres are becoming more and more popular. Gravel and adventure bikes offer a new option for the growing number of cyclists that want a versatile bike to cover different road surfaces and terrain (and previously might have chosen a cyclocross bike) and with 650B is back in fashion in the mountain bike world. All of that has made bike makers look again at a wheel size alternative.

With the mountain bike industry geared up to developing 650B bikes, there’s now a lot bigger choice of wheels. There’s also a cross-pollination of ideas and engineering, especially with the growing gravel and adventure bike sector, which owes a lot to the mountain bike world. It was really only a matter of time.

How Cannondale went 650B with the Slate

When it launched the Slate a couple of years ago, Cannondale reckoned that a 650B rim with a 42mm tyre was the perfect pairing for a bike designed to be fast and agile on the road, like a regular road bike, but capable when the surface turns to dirt and gravel.

Cannondale Slate - 1.jpg

- Cannondale Slate - First Ride Review

“On Slate, the decision to go for 650B was natural for us,” Cannondale's David Devine says. “We knew which tyre size we wanted, 42mm. We knew which chainstay length we wanted, 405mm. When we discovered the rollout of 700x22mm and 650x42mm were roughly the same, we decided it was the best wheel size for achieving our desired tyre volume within the set geometry. Traditional 700C wheels, paired with the 42mm tyre would have driven a longer chainstay length, and would have necessitated a higher frame stack while maintaining the same 30mm Lefty Oliver Suspension fork.

“650B wheels offer our desired geometry and tyre volume together in one package, rather than having to make a compromise with smaller tyres or longer chainstays,” explains Devine.

The bespoke option

It’s not just the big players in the cycling industry that are paying attention to the benefits of 650B. Bespoke frame builders have been closer to the cutting-edge of bicycle design than many of the bigger corporations for some time, with a closer relationship to their customers and able to produce one-off frames much more quickly.

Hallett 650b

Richard Hallett of Hallett Handbuilt Cycles has been dabbling with the 650B wheel size and appears convinced of the benefits, saying that ride comfort and grip are the big advantages.

“650B road tyres such as the Grand Bois Cypres and Hetre offer demonstrable improvements over 700C tyres up to 28c in rolling resistance, ride comfort, grip, all-roads riding and, importantly, safety,” says Hallett, “so using 650B wheel and tyres I can build a touring, audax, utility or training bike that offers superior performance in these respects.

“There is a weight penalty, the amount depending on tyre size, which is why they aren't used in racing. If someone wants a racing or sportive bike, I recommend 700C, up to 25mm.”

Road.cc took a closer look at one of Richard Hallett’s bespoke bikes last year, a steel frame and fork with 650B wheels and 42mm tyres. His aim was to build a fast, comfortable and fine-handling bike and put it through its paces in the 300km Dragon Ride sportive, a stern test indeed for any road bike.

We’ve been here before haven’t we?

Sort of, yes. Using smaller mountain bike wheels on a road bike is nothing new of course. There have been many road bikes designed with 26-inch mountain bike wheels that allow clearance for larger tyres: the Surly Long Haul Trucker is one such bike that can, as well as regular 700C wheels, take a 26in rim with a tyre width up to 62mm.

Hallett 650b - rear brake

While such bikes have been a quirky oddity to most regular road cyclists, the growing popularity of wider tyres on all road bikes and a shift towards comfort over outright speed, could mean we'll be seeing a lot more new bikes that take a fresh look at the advantage of combining a smaller wheel with a bigger tyres.

Was Cannondale’s Slate the start of a new trend or simply a one-off? David Devine thought at the time that we were likely to see more manufacturers take an interest.

“I do anticipate that other bike companies will trend toward making 650B road bikes,” said Devine. “Already, we have some tyre manufacturers approaching us to make sure they are opening moulds that will be compatible with Slate. In addition to the tyres available from Panaracer, you will see tyres from some of the main brands already coming to the market in this size. The Slate will help broaden the tyre selection for 650B x 42mm tubeless, all-road tyres. It’s something that has been around in the hand built community for some time.”

While there are clearly some very good reasons for going to a 650B wheel sizes, there are some downsides. A 42mm tyre is heavy, about 400g, about twice the weight of a regular narrow road tyre, and that can extra weight at the outside of the wheel could impact acceleration and speed. Those concerns might be easily outweighed by the comfort, durability and robustness for tackling rough roads and gravel paths and off-road tracks, though. 650B could make sense to a lot of cyclists.

Perhaps the mainstream bike brands won’t have it all to themselves, argued Richard Hallett.

“The large-scale manufacturers seem to have put all their eggs in the 700C wheel basket so we see everything from race and sportive bikes on 700Cx23/25 to gravel and adventure bikes with 700Cx32/35 tyres,” he said. “These are inevitably heavier than 650Bx32 with no appreciable performance advantage, but investment in 650B would cost money, so I suspect 650B road bikes will remain a small part of the market for the moment.”

The latest 650B bikes

Two years later, it looks like Hallett was more or less right, but a few more manufacturers have taken the plunge and added a 650B-shod bike to their ranges. Canadian brands Kona and Norco both have gravel bikes with 650B wheels, as do the UK's Genesis, Chain Reaction Cycles house brand Vitus and boutique marque Mason Cycles.

And after being very hard to find, the Slate is back in the UK for 2019 with two models, both with SRAM 1 X 11 transmissions and the Lefty 30mm suspension fork. Cannondale still describes the Slate as "a full-tilt road bike with legit off-road chops" a rather confusing line, but at least the new models come with knobbly tyres.

Cannondale Slate — £ 2,699 & £ 3,199

2019 Cannondale Slate SE Force

For 2019 Cannondale offers two models of Slate, with SRAM Apex and SRAM Force at the lower and higher price points respectively. Aside from the difference in groupset quality, the specs are very similar. Both have 44-tooth single chainrings with 11-42 cassettes and knobby WTB Resolute tyres.

Find a Cannondale dealer

Genesis Fugio — £1,549.99 & £2,199.99

2018 Genesis Fugio

The Genesis Fugio, above, is solidly a gravel bike, with 50mm tyres. It’s almost a mountain bike with drop bars, and fits the growing trend for big tyred drop bar road bikes that can go almost anywhere. The frame is made from Mjölnir chromoly double butted tubing, with a full carbon fibre fork.

There are two models for 2019, Fugio 20 and Fugio 30. Both have SRAM 1 X 11 transmissions with 42-tooth chainrings and 11-42 cassettes. The Fugio 20 has SRAM Apex components, cable-actuated disc brakes and Donnelly X'Plor MSO tyres, while the more expensive Fugio 30 gets SRAM Rival parts, hydraulic brakes and WTB Byway tyres.

A Fugio frameset is £799.99 and you can still pick up a 2018 Fugio for £1,600 with a Shimano 105 groupset and RS-505 hydro brakes.

Find a Genesis dealer

Norco Search XR — £1,350-£3,350

2019 norco search xr c force

Norco's Search XR is a 650B-capable version of the Search bike that Norco has been offering for a few years. There are four models in the UK range, two with carbon fibre frames and two with frames in Reynolds 725 heat-treated chromoly steel, an unusual move that will no doubt endear the Search XR to UK steel frame fans.

The range starts with the £1,350 Search XR STL Apex and you can probably guess most of the spec from the name. It has the Reynolds 725 steel frame, and SRAM Apex transmission. There's a 40-tooth single ring up front and an 11-42 cassette and TRP Spyre cable-actuated disc brakes do the stopping.

Next up, the Search XR STL Rival hangs Rival components and hydraulic brakes on the same frame, and widens the gear range with a 10-42 cassette as well as the 40-tooth cassette.

At £2,250, the Search XR C Apex is the cheaper of the two carbon-framed models. It has SRAM Apex components, hydraulic brakes and a 10-42 cassette.

The top-of-the-range £3,350 Search XR C Force, above, has Kenda Small Block 8 Pro 2.1in tyres and a dropper post, making it hard to tell at first glance that it's not a full-rigid mountain bike with drop bars.

Find a Norco dealer

Kona Rove — £1,139-£3,399

2019 Kona Rove NRB DL

Some models of Kona's venerable Rove adventure/touring bike come with 650B wheels, though the frame will also accommodate 700C wheels. There are two aluminium-framed bikes, including the Rove NRB, above, and two with steel frames, including the range-topping Rove LTD in Reynolds 853.

Vitus Substance V2 — £1,049.99

2018 Vitus Substance V2 105.jpg

A new model for 2018, the Substance V2 has a chromoly steel frame and carbon fibre fork and comes in two versions, with Shimano 105 components, above, or with SRAM Apex 1X. Both have hydraulic disc brakes, so the only major difference is whether you want the simplicity of one chainring or the versatility of two.

Ibis Hakka MX — from £3,349

Ibis Hakka MX14.jpg

The Ibis Hakka MX is a descendant of the US company’s previous Hakkalugi cyclocross bike but geared much more towards the gravel and adventure riding, rather than racing in the mud. Like most of the bikes here it will take 650B or 700C wheels, though you get the fattest tyre option with 650B: the stock Schwalbe Thunder Burt tyres are 54mm wide. It's a long way from cheap even in the base SRAM Rival 1X spec above, but you're getting a frame from one of the best-regarded carbon shops in the business.

Mason Bokeh — from £3,100

Mason Bokeh.jpg

From the detail-obsessed mind of Dom Mason comes a highly capable adventure bike with a feature-packed aluminium frame, splendid aesthetics, and handling that ensures it's as at home on the road as it is on the trail.

Read our review of the Mason Bokeh Force

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Road.cc buyer's guides are maintained and updated by John Stevenson. Email John with comments, corrections or queries.

David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.

14 comments

Avatar
CXR94Di2 [2510 posts] 3 years ago
0 likes

Get a road bike frame that can take 38mm tyres, then you have the benefit of extra cushioning and increased rolling diameter 

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eddyhall [52 posts] 3 years ago
0 likes

So if I were considering a new bike now, I could spec up on 700x25 but in the future I could change to 650x32 without any reworking?

Avatar
don simon fbpe [2944 posts] 3 years ago
0 likes

How

much

comfort

will

I

have

when

the

650b

are

pumped

up

to

higher

pressures

for

road

riding

?

 

Avatar
dave atkinson [6491 posts] 3 years ago
0 likes

don simon wrote:

How much comfort will I have when the 650b are pumped up to higher pressures for road riding ? 

depends what you mean by 'high'

I'm not running 650Bs at the mo but I am running big tyres: 38mm Schwalbe G-Ones. road riding pressure for them is about 60psi

Avatar
dave atkinson [6491 posts] 3 years ago
0 likes

eddyhall wrote:

So if I were considering a new bike now, I could spec up on 700x25 but in the future I could change to 650x32 without any reworking?

if you were running discs you could, and it wouldn't materially affect the handling because the rolling diameter is similar

Avatar
Cupotea [21 posts] 3 years ago
0 likes
Dave Atkinson wrote:
eddyhall wrote:

So if I were considering a new bike now, I could spec up on 700x25 but in the future I could change to 650x32 without any reworking?

if you were running discs you could, and it wouldn't materially affect the handling because the rolling diameter is similar

 

That's really not true, is it?  Most road forks and frames would not be able to fit the additional width in even if the circumference is only the same as a 700x25.

Also,  I'm assuming the stays joining the BB shell will need to be wider/further apart if there is no increase in stay length.  Is there an increased q-factor?

 

Avatar
Phil T [35 posts] 3 years ago
0 likes

Lots of information on the benefits of 650b wheels here;- http://www.bikequarterly.com/

The magazine's a good read too.

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Andrewwd [40 posts] 3 years ago
0 likes

"additional cushioning from the bigger volume of air"

This isn't accurate; it's the tyre pressure which affects the cushioning. 90 psi in a 650B tyre feels the same as 90 psi on a 700C.

 

"a larger contact patch which boosts traction"

This is also innacurate; contact area does not affect traction,

 

The 650B tyre shown has very tall sidewalls which would need to be strengthened to be stable. This adds to tyre weight.

Avatar
fennesz [156 posts] 3 years ago
3 likes

Yeah - let's go the way of the mountain bike world with massive changes every couple years & the industry chasing the next 'big' thing.  

We'll see this with disk brakes - add in new wheels sizes and it compounds the problem.  Try buying a MTB & your head will be spinning with the number of options.  & you thought the BB standards were a pain.  The whole niche bike/new stantard is purely to get us to by more bikes: one bike for every likely scenario.  

Avatar
dafyddp [464 posts] 3 years ago
7 likes

I bought this Paris Rochet in a brochante a couple of years ago, it's about 50 years old I think. Complete with 26 x 1 3/8" 650B Michelin tyres.

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ItsHuddo [7 posts] 3 years ago
0 likes

I can vouch for how comfortable a 26 x 1 3/8 tyre is! Anyone who has ridden an old three speed will be able to tell you. It's about the same size as a 650b, and makes the world of difference when riding around town.

The weight issue of the larger tyre will put off the pro market, I would've thought, and so it'll be interesting to see what takeup is like among the hoi polloi who try to emulate their heroes.

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sam_smith [81 posts] 3 years ago
0 likes

I think I'm going to hold off on buying a new touring bike for a few more years until 650B is more of a standard amongst manufacturers.

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Tim Rice [1 post] 2 years ago
0 likes

Will it be mainstream future, no probably not. Yet for bicycle enthusiast I think that 650b will be the future. Depending on where you live. Roads seem to be getting worse. Or depending on how many bikes a person has, plush is a nice option.

For example I bought a Trek crossrip to be plush, but the 700x40c tires are heavy. So while I am not looking to break speed records, I really wish to enjoy a plush ride. Disheartening to me was the discovery that my Cannondale Syna...pse on a 25c is more comfortable than my Trek Crossrip on a 40c
There is also the factor that the Trek Crossrip rides better on a smaller diameter tire. Enter the 650x42 Panaracer Gravelking option. I should shed grams on 650wheelset. and I lose around 100g a tire. If I go tubeless even more. I estimate a move from 700x40 to a 650x42 sheds 200-300g. With the advantage ofthe bike feeling like it is on 23's However 1/2 lb on this bike with rack, fenders, lights.... pointless argument. Albeit a rotating mass reduction.

Will I convert though? I don't know... there are too many options out there around the 650b wheelsize. If I want fun and zippy and capable then the Slate is the answer. If I want a nice leisure plush ride. That is still cabale of bikepacking, do it all, utility, commute there is the diamondback Haanjo EXP.
Regardless, If I don't mind the Trek crossrip on a 28c tire, but miss the plush ride of a 40c, a 650bx42 seems like the answer. and a wheelset is much cheaper than a new bike. It also leaves a door open to go to a dynamo hub on this bike. Oh the joys, of never worrying about if my Light battery is charged.

Avatar
Rider X [19 posts] 11 months ago
0 likes
Tim Rice wrote:

Will it be mainstream future, no probably not. Yet for bicycle enthusiast I think that 650b will be the future. Depending on where you live. Roads seem to be getting worse. Or depending on how many bikes a person has, plush is a nice option.

For example I bought a Trek crossrip to be plush, but the 700x40c tires are heavy. So while I am not looking to break speed records, I really wish to enjoy a plush ride. Disheartening to me was the discovery that my Cannondale Syna...pse on a 25c is more comfortable than my Trek Crossrip on a 40c
There is also the factor that the Trek Crossrip rides better on a smaller diameter tire. Enter the 650x42 Panaracer Gravelking option. I should shed grams on 650wheelset. and I lose around 100g a tire. If I go tubeless even more. I estimate a move from 700x40 to a 650x42 sheds 200-300g. With the advantage ofthe bike feeling like it is on 23's However 1/2 lb on this bike with rack, fenders, lights.... pointless argument. Albeit a rotating mass reduction.

Will I convert though? I don't know... there are too many options out there around the 650b wheelsize. If I want fun and zippy and capable then the Slate is the answer. If I want a nice leisure plush ride. That is still cabale of bikepacking, do it all, utility, commute there is the diamondback Haanjo EXP.
Regardless, If I don't mind the Trek crossrip on a 28c tire, but miss the plush ride of a 40c, a 650bx42 seems like the answer. and a wheelset is much cheaper than a new bike. It also leaves a door open to go to a dynamo hub on this bike. Oh the joys, of never worrying about if my Light battery is charged.

 

Tire construction matters just as much as size.  An overbuilt (aka heavy) 700x40 tire will have a stiff casing, which will not provide a plush ride.  A more supple 700x25 tire at the right pressure could be a more plush ride.  I would try a better tire on the crossrip first before going to a different wheel size, with all those added costs.