650b vs 700c for one bike to rule all roads?

[thollandpe]

This bike makes 700 x 35's feel like road tires.



Except when traveling at Ludicrous Speed over detritus that would eat 23's or 25's for breakfast. Then it's apparent that Something Wonderful is happening.

Looking forward to trying 650b x 38's of 42's on this, but maybe not. It's so good (and if I figure out tubeless, even better).

[Too Tall]

What's your inseam?


- Garro.

What he said. In my case I'm a giant human being with feet to match. Not that you should include giant people in your sampling.

[rec head]

This bike makes 700 x 35's feel like road tires.



Except when traveling at Ludicrous Speed over detritus that would eat 23's or 25's for breakfast. Then it's apparent that Something Wonderful is happening.

Looking forward to trying 650b x 38's of 42's on this, but maybe not. It's so good (and if I figure out tubeless, even better).

That is a classy looking bike.

If I had to keep one I would take my 650b bike with 42's over my 700c bike with 28's.

[TTX1]

This bike makes 700 x 35's feel like road tires.



Looking forward to trying 650b x 38's of 42's on this, but maybe not. It's so good (and if I figure out tubeless, even better).

You’re welcome to try my 650b x 42 hoops - DT/Campy should line up...

[Greg Costello]

I think the proposition of a one road all road bike fails once the range gets too large. Optimal geometry/dimensions for a 700c road bike for good paved roads differs than on a bike built around 40mm plus tires, at least that's my experience. I don't like anything bigger than a 32 and even that is pushing it one a "road" bike. I like my 650b x 47 combo on dirt/single track but not so much on the paved road to the trail. Yeah it's fine, just far from as fun as a road bike with veloflex arenbergs. Besides, how do we adequately support our friendly framebuilders by just having one do it all bike

[Marin]

32 and even that is pushing it one a "road" bike. I like my 650b x 47

Well, there's 650x42 sitting right in middle. Pari Motos tubeless and you're set.

[boots2000]

So much of this falls into “it depends”.
Depends on specifics of the frame, wheels, tires, tire pressure, bike setup and rider experience.

I was always a 650b hater- figured they were slow and unnecessary.

Fast forward to my new relationship with an Open Upper. I put Enve G27 650b with Schwable Thunder Burt 2.1 tires on the bike to start.

1st ride confirmed slowness- but that was at Enve recommended 21 psi.
Did another ride mid-week, all road 40-42 psi. I started to think “maybe I judged too quickly”.
Did another gravel ride with lots of vertical and longer descents, singletrack,etc.. Split the difference in pressure- 30 up front and maybe 35 rear.
Didn’t feel slow, lots of traction and control on descents and singletrack.

[Greg Costello]

Well, there's 650x42 sitting right in middle. Pari Motos tubeless and you're set.

Yeah, I've tried 650 x 42 on my Spectrum which is designed around 700 x 28. It's ok. It's not a Bora 35 with veloflexs. Horses for courses and if the course is mixed surface then yes a do it all bike is ideal and I'm glad I now have a few bikes that can cover this ground. But its not the same bike or wheelset I'm taking to tackle paved rides in the Alps nor is it the bike I'd choose for relatively tame forested singletrack but with enough rooty or rocky sections to make a wider, higher volume tire and a bike with different geometry and clearances a better choice.

[robin3mj]

It’s been 11 months, so this thread deserves a bump.

New, but tangential question: The V-Salon/handmade market notwithstanding, Has the retail bicycle market made a decision on this 700 vs 650b topic?

• Cannondale Slate (which I own) was released to great fanfare in 2015 and not really updated. Since then, they have come out with the Topstone in AL and Carbon, the latter having some sort of rear suspension.
• Trek’s gravel bike is 700c only
• Specialied Diverge/Sequoia are sold with 700c but advertised as having clearace for 650b

Smaller brands like Salsa and Surly seem to offer more of a mix.
More and more new tires seem to be offered in many more 700 widths than 650.

Anyway, overall, a few years ago it felt like 650b was on the cusp of becoming a more established “thing” and then the tide seems to have ebbed a bit. Assuming this is not just my imagination, my question is: why? Fewer SKU’s, too much effort to establish a new standard, gravel riders are taller than the average cyclist, etc?

[32x20]

New, but tangential question: The V-Salon/handmade market notwithstanding, Has the retail bicycle market made a decision on this 700 vs 650b topic?

I follow mtb tech more, but it sure seems like ‘allroad’ is following in the mtb market’s footsteps: 700c is (marginally) faster, so that’s what gets built and sold. I’m sure that breaks down at the bottom of the height bell curve, but 650b seems to be fading in favor of 700/29.

[doomridesout]

I can't believe I never weighed in on this thread (I'm sure I was on 50 other 650b threads, this one fell through the cracks). I ran 650x38 Gravelkings tubeless on carbon rims for the last year in Humboldt. It's pretty much 5% decent pavement, 65% rutted pothole pavement, and 30% buff dirt. Much of it is very steep climbing, including long sustained climbs.

It was perfect. Light rims and tires at fairly high pressures of 35-45 felt nearly as fast and responsive on climbs as 700c road wheels, but I felt far more comfortable bombing sketchy descents quickly. I still didn't feel great about traction on looser dirt, but that's stuff for your MTB, not your allroad bike. Maybe I would sing a different tune with a centimeter wider tire, but then you're not on the bike to rule the pavement anymore, are you?

[sk_tle]

I tend to think that a bigger diameter trumps a bigger volume in term of rollover capabilities and carrying speed. Same on an MTB I prefer a regular 29er than a 27.5+ which has loads of traction but is less capable on the rooty/rocky stuff.

650b gravel bikes were advertised as do it all bikes as you can easily swap from 650x47b to 700x28c without changing the wheel diameter and keep trail and BB height the same. However from my own experience and what I see with friends people tend to stick to one diameter, especially because these kind of bike are often sold with 1x gearing with a range not really suited for fast group road rides. If you are riding on your own or with a couple of friends with similar bikes you just don't mind the slight decrease in overall performance by riding with knobs so you will usually stick with the "dirt" setup.

Where 650b shines is really for city /commuting/touring. I'm riding 650bx1.9ish panaracer gravel king. The overall wheel diameter is really close to my road bike with 700x28c tires so with close contact points I really feel at home on both bikes and they feel agile and snappy. However I can ride it with bags attached to the rack in full comfort. The bike handle the numerous transitions between road shared bike lanes and sidewalk shared bike lanes without being unsettled as well as the short but rough shortcut on a dirt path. Having a comparable usage with 700c diameter would have me having to find a compromise between a more truck like handling or lack of volume and comfort with load.

So if you plan to ride with load mostly on roads (dirt or not) I say 650bx45-52mm is great. If you want to race gravel or just want to go fast I'd say 700cx38-45mm. If your primary use is rougher stuff and singletrack you should have bought an MTB.

[TTX1]

Anyway, overall, a few years ago it felt like 650b was on the cusp of becoming a more established “thing” and then the tide seems to have ebbed a bit. Assuming this is not just my imagination, my question is: why? Fewer SKU’s, too much effort to establish a new standard, gravel riders are taller than the average cyclist, etc?

I think you nailed it. For the average Joe, walking into a bike shop is already complicated. Bikes with swappable wheels are extra complicated. It’s not a recreational or low effort option - there are no absolutes, but its a solution that appeals mainly to aficionados. For the manufacturers, it’s added cost to hit yet another niche. For the retailer, it’s easier and more profitable to sell a second wheelset rather than a package. For the consumer, particularly the aficionado, it’s about choice and preference in the first place. And again, there’s extra cost.

I rode 650x42 a lot until this year. My new bike was designed for 650/700 swaps, but I quickly found that 700x35 is my goldilocks setup and I don’t have a lot of motivation or occasion to swap. I kept the 650 wheelset and will set it up with fatter knobby tires for winter... I still get the benefit of swap-ability, but with a slightly different set of use cases than originally envisioned.

That’s the rub, in terms of mass appeal: use cases are diverse - it’s a huge challenge for marketing / positioning.

The fact is that some 700c bikes naturally fit 650b, but only a subset of those actually feel right and perform well for a given rider. There’s nothing new here. ”new” allroad bikes - like the Slate - are not really different in that most people end up riding their preferred wheelset most of the time. And bike shops would rather sell two bikes, or more, in the first place... just demo’ing a bike with two wheelsets is sort of a nuisance, for everyone involved.

Especially since the demo doesn’t reveal as much about the versatility of the frame as it does about the relative feel of the wheels...

[bryand]

I’ve been experimenting with this since April. I’ve been riding 650x42 tires on a bike that (on paper) is virtually identical to one of my favorite frames built around 700x25 tires. Chainstays are within 2mm, stack & reach are identical as are the contact points and frame materials, but that’s where the similarities end. The 650b bike has disc brakes, the 700c bike has rim brakes.

The 650x42 wheels & tires have an actual width of 44.1mm and a diameter of 675 mm.
The 700x25 wheels & tires have an actual width of 28.2 mm and a diameter of 684 mm.

Both rims are carbon and both tires have a smooth rolling surface with a herringbone side tread. I get an actual diameter difference of 9mm. Both frames have the same bottom bracket drop of 75mm, so if I do the math based on wheel diameter I can conclude that the 700c bike is 4.5 mm higher off the ground.

Here’s what I feel:
The 650 bike feels heavy while riding (and in fact is noticeably heavier) compared to the 700 bike. The disc brakes, wheels & tires all add up for sure.
The 650 bike wants to go straight. Yes, it’s very stable and easy to ride in sketchy situations or on the edge of the road without nervously wanting to drop off a tall shoulder. It actually does turn fine, but it feels like I need to put some effort into it. It makes for confident descents around 45+ mph but there is a definite sense of work required.
To get the 650 bike to feel a little more lively I often run my tire pressures higher than I would like. I weigh 162# and I often run front and rear around +/- 55psi if the majority of my time will be on pavement.
The 650 bike feels slow. It’s slow to accelerate, it’s slow to climb and I often use lower gears than I would on the other bike.
The 650 bike with lower tire pressures is nice to ride on the dirt roads and the bike feels more spirited there. It still feels slow climbing on the dirt; descending can be very fast and I trust the bike.

Here’s my theory:
I’m not convinced the 4.5 mm difference in tire radius is really affecting the handling, although those who study “trail” may disagree. I think the 650 tires just have so much more grip on the pavement, especially at low pressures. This is visually really obvious due to tire volume, but I think it’s just a lot of surface contact that is slowing everything down which is compounded by the very noticeable difference in wheel/tire weight.

Again, just sharing my thoughts based on a lot of pedaling this season. Feel free to chime in.

[Matthew Strongin]

Interesting. What are the wheels and tires?

[sk_tle]

living along a coast line I'd say that the difference in speed between 650b + wide tires and road bike wheels is less than the difference made by a slight change in wind speed/direction. My commuter definitely feel a bit slower but on good day it still feel much faster than my road bike in a windy day. In that sense I'd say the difference is small and negligible if you are on your own and don't try to do cat6 racing.

[mzilliox]

curious to hear more. I have not enjoyed 650b 38s or 42s as much as i thought i would. they also feel very slow to me overall. i also seem to run them at high pressures to get better performance, like 55 rear 50 front at 145lbs. i also find 700c 32s or 35s to be my sweet spot for gravel.

however im in need of a bike with disc brakes because my hands are trash now, and i need the help braking. so as i decide, i need to decide on tire clearances and wheel standards. im thinking of just staying 700c with max tire of 38mm.

looking forward to more input from the salon.

[ChristianWong]

I'm going to be moving in this direction shortly.

I'm expecting to spend the majority of my time on 700c (35-40mm tires) but have a 650b x 48-53mm wheelset for really rough stuff or light bike-packing duties. The way I see it, the 650b wheelset will be for going (relatively) slow - either loaded with bags or on technical terrain.

The use-cases for the separate wheels will be so different that there will be no point in comparing. Maybe that's the key to buying into this 'one bike to rule all roads' philosophy?

[Applesauce]

Again, just sharing my thoughts based on a lot of pedaling this season. Feel free to chime in.

I have no experience with 650B road bikes, except to say that they're not selling very well. My shop isn't exactly in deep, so this isn't a personal issue for me.

Everything you said of 650B road bikes vs. proper 700C is equally true of 27+ MTBs vs. proper 29ers, however, which is something I have lots of experience with. 27+ sucks in almost every higher-performance application, and has pretty much died. Is 27+ good for eBikes and newbs and groms? Probably. But of those three categories, the only one I take seriously is the one that subsumes my seven year old, who's right at home on a little "plus" bike.

My cynical prediction for the road-plus market is that for a few years we'll see dwindling sales and lots of folks holding out in the interest of justifying their purchases, and the slow drift back to traditionally accepted wheel and tire sizes. Nothing wrong with any of that, I'll add; it's the normal course for cycling innovation. But if flavours of plus hang on at all, it'll be in a hella-niche capacity, where the bounciness and imprecision are either irrelevant or advantageous.

[thollandpe]

curious to hear more. I have not enjoyed 650b 38s or 42s as much as i thought i would. they also feel very slow to me overall. i also seem to run them at high pressures to get better performance, like 55 rear 50 front at 145lbs. i also find 700c 32s or 35s to be my sweet spot for gravel.

however im in need of a bike with disc brakes because my hands are trash now, and i need the help braking. so as i decide, i need to decide on tire clearances and wheel standards. im thinking of just staying 700c with max tire of 38mm.

looking forward to more input from the salon.

Before I picked up the Zank, I ran rim brakes: mini-vees with road levers, and Kool Stop salmon pads. They had oodles of power and I never needed more brake. I needed rims with fewer dents, however.

Latest tire combo is 700x38 in back, 700x35 in front. Best yet!

OK those with two sets of wheels, have you mixed the diameters yet?