26 inch vs 650b for tiny frame

[Doug Fattic]

I was thinking like a custom frame designer and not a customer choosing which tire width works best for certain riding conditions. The reason I was pointing out 650b is similar in circumference to a 700c is because some people mistakenly think the 650b wheel is smaller. It’s not. It is still a big wheel. That was my point and not which width of tire works for the kind of riding she is wants to do.

So if you choose 650b wheels there is probably going to be toe overlap that can cause an inexperienced rider to go splat on the ground if they turn their handlebars so their wheel hits their foot. Fit cyclists ride faster and turn by leaning so toe clearance isn’t the issue for them. Production companies get around toe clearance with steep seat angles and shallow head angles that are not optimum for either rider position or handling.

[palincss]

Originally Posted by everbeek

Try 650c (not b) wheels.
-Mike

Except that 650C tire availability is poor. You're limited to very narrow tires (the widest tire in that size is a seldom-seen 28mm and it's not what you'd call supple).

[Burning Pines]

[QUOTE=Doug Fattic;2501792]I

[Doug Fattic]

Originally Posted by Burning Pines

What are you even talking about? 650b is objectively smaller than 700c. The rim diameter is literally different.

Paceline: come for user ultegra cranksets, stay for a multi - post argument about how numbers are meaningless.

Yes a 650b rim is smaller than a 700c but 650b tires are bigger than 700c tires. So the outside diameter of both tires are about the same. According to a Cateye computer tire size chart, a 650b X 38 tire has a circumference of 2105 mm. A 700c X 25 tire also has a tire circumference of 2105. Doing the math that gives them a radius of 335mm. That 335mm is the distance from the center of the hub to the outside of the tire that a toe wants to miss.

So, Burning Pines, the main point of my post was to explain that many people like yourself falsely believe that 650b tires are smaller than 700c tires when in fact they are about the same size (unless one is using fatter 700c tires). I wanted to point this out so that one would not make the mistake of believing a 650b tire gives more toe clearance when in fact they do not.

[palincss]

Originally Posted by Burning Pines

What are you even talking about? 650b is objectively smaller than 700c. The rim diameter is literally different.

Of course they are. However, in some cases -- e.g., 700Cx23 and 650Bx42 the outside diameter of the mounted tire can be virtually identical.

Which, after all, was exactly the point of the nnn ABC system in the first place. The overall diameter of wheel + tire would be the same, with smaller diameter rims taking wider/larger tires and larger diameter rims taking narrower tires. (Of course, that system was devised in a day when brakes used to clamp onto the seat stays and fork blades.)

[zap]

Note, 650b is also available in 25 size........smaller diameter for smaller road frames.......example Canyon wmn in the two smallest sizes.

[ColnagoC59]

if you are going 32mm tire or larger 650 tires make a lot of sense to me. wish i went that route on my firefly. had no idea how 32's would change the profile compared to the 23's on my road bike

[Doug Fattic]

Back to the OP’s question about which tire size to use and what affect that might have on handling. If my wife was small and just a normal recreational rider I would definitely choose 26” MTB size. My 1st concern would be that she has toe clearance unless she was an experienced cyclist that likes to ride at speed. That kind of rider is likely going slower and sometime may turn by turning her handlebar and if her foot hits the front wheel there is a good chance she is going down. If my wife hit the ground because her toe hit the front wheel, she would think I was an idiot for my frame/component choices for her bike.

Another advantage of smaller diameter wheels is the she will be seating closer to the ground for easier foot down at stops. In addition a lower bottom bracket height caused by smaller wheels gives better handling characteristics. Looking up the geometry of the 2016 Soma double cross I see that the BB drop is 66mm. Production frames have a higher bottom bracket drop just in case someone puts on longer cranks or likes to pedal through corners at speed. The point is that in this case choosing smaller wheels is a double advantage for both easier foot down and more stable handling with a lower bottom bracket height. Those factors would trump tire choices in my opinion. Decent enough tires can be found in whatever tire size is chosen.

If I was choosing which wheels to buy, I would plug in the numbers into BikeCad and see what tire (and crank length) options give me toe clearance. It is not smart to fail that minimum requirement. Just for grins I looked up the tire radius of a 26 X 1.5” tire. At 316mm, it is 9mm less that a 650b X 38mm tire that has a 325mm radius. Of course smaller width tires can be chosen in either tire sizes depending on where she will be mostly riding.

Since she is short she probably would benefit from 165mm cranks to help with toe clearance.

Just to understand where my opinions are coming from I’ve been a custom frame builder for over 40 years and a lot of my customers have been women that have had trouble getting properly fit on production made bicycles. The solution is often to design and make a frame with smaller wheels.

[iPaul]

OK so this thread is timely for me as my wife of 5’2” is looking for a new road bike. Her current bike is 700c wheeled and her fit just seems compromised to me. This got me considering a 650B bike. She will do mostly road rides with some hard gravel recreational trails.
A tire width of 33 mm would be max for the bike we are considering, which is plenty. Issue is finding a 650B tire in that width range which makes us looking at 700c bikes again. Are their mid-level tires out their? Do they fall in the 27.5x1.25 category? Thx

[palincss]

Originally Posted by iPaul

OK so this thread is timely for me as my wife of 5’2” is looking for a new road bike. Her current bike is 700c wheeled and her fit just seems compromised to me. This got me considering a 650B bike. She will do mostly road rides with some hard gravel recreational trails.
A tire width of 33 mm would be max for the bike we are considering, which is plenty. Issue is finding a 650B tire in that width range which makes us looking at 700c bikes again. Are their mid-level tires out their? Do they fall in the 27.5x1.25 category? Thx

Grand Bois Cypres 650Bx32
https://cyclesgrandbois.com/SHOP/T650_F32_SS.html

Hutchinson "Confrérie des 650B" 650Bx32
https://www.xxcycle.com/tyre-hutchin...0-b-ts,,en.php

[ericssonboi]

On the 26" rim front, what would everyone recommend? Brake rim and 32h for the build.

[Burning Pines]

Originally Posted by Doug Fattic

Yes a 650b rim is smaller than a 700c but 650b tires are bigger than 700c tires. So the outside diameter of both tires are about the same. According to a Cateye computer tire size chart, a 650b X 38 tire has a circumference of 2105 mm. A 700c X 25 tire also has a tire circumference of 2105. Doing the math that gives them a radius of 335mm. That 335mm is the distance from the center of the hub to the outside of the tire that a toe wants to miss.

So, Burning Pines, the main point of my post was to explain that many people like yourself falsely believe that 650b tires are smaller than 700c tires when in fact they are about the same size (unless one is using fatter 700c tires). I wanted to point this out so that one would not make the mistake of believing a 650b tire gives more toe clearance when in fact they do not.

Sure, sorry for the aggressive tone.

[owly]

BlueLug has a couple of Panaracer 'Fairweather' 26" tyres. Mild and XC:-
https://global.bluelug.com/bicycle/t...be/26inch.html

[fogrider]

a friend had this issue and went with a brand specifically designed for smaller riders...I can't remember the name of the brand right now and I'm not even sure they are still in business, but they used a smaller front wheel, I think it was a 24" front wheel and a 700c rear wheel. Also, consider using shorter cranks...160 or 162.5s?

Also, if you really want wider tires, it would be fair to say 650b in a 40mm tire is smaller than a 700c in the same 40mm tire.

[thwart]

Originally Posted by ericssonboi

On the 26" rim front, what would everyone recommend? Brake rim and 32h for the build.

Wife’s bike (48 cm Waterford 1200) was designed around 650c wheels, but I converted it over to 26 inch wheels two or three years ago due to the lack of wider rubber available in 650c. Used some vintage Mavic 317 rims I picked up here... 17 mm internal width.

Running Specialized Fatboy Flak Jacket tires, which are approximately 32 mm wide.