Noonievut

I’ve read about wheel diameter between both sizes of wheels with different tires, though I was wondering if there is information on specific tires using same rims to give a good comparison (I realize many other differences impact the specific measurements, I’m looking for ballpark).

My gravel bike has 700x40 and on slow, tight turns there is a risk of toe overlap if I’m not careful. On a regular ride (paved or gravel roads) they’re fine. But I have some nice trails by my house and was thinking of a 650b wheelset with aggressive tread. Would love to know overall diameter differences between 650b 42, 44, 47. And 700 38, 40, 43 (e.g. GKSK or GKSS).

Any sites you’re aware of with some info?

Thanks and happy holidays

dsaul

This site has a pretty extensive list of tire diameters. It doesn't take rim width into consideration, but its a great way to compare wheel and tire sizes. https://www.bikecalc.com/wheel_size_math

sloppy12

Just know if you get a smaller 650b its gonna drop the bottom bracket and you will get pedal strikes.. If you match the size in 650b so like swap to 1.9-2.1"(should be real close) you might still get the toe overlap but you get way more tire for ruff stuff.

Personally I think toe overlap really doesn't matter on slow technical at all. nothing happens.

Rolla

I've got a bike with 700 X 35 that has no toe overlap at all. My 650 X 47 has a little. My 700 X 42 has a lot. Personally, I wouldn't choose wheel size (or wheels) based on potential overlap. IME, foot position, shoes, and pedals have as much to do with it as anything else. Like sloppy12 says, on slow speed turns it doesn't really matter anyway; just back-pedal an inch or straighten the wheel a tad and keep going. Eventually you'll develop the muscle memory to prevent it in the first place.

Noonievut

Thanks for the replies.

I decided to measure my road bike and gravel bike. The gravel bike is pretty new and the handful of rides felt like I was sitting really high up. Some of the gravel bikes I’ve owned felt like this, others like I was lower. I never gave this much thought and never measured anything. My road bike has always felt very ‘planted’. I much prefer being planted!

So my road bike with 700x25 has a BB height of 27cm (middle of BB). And the pedal at 6 o’clock is 10cm from the ground (172.5 crank arms).

Gravel bike with stock 700x40 is 29cm high (170 crank arms). I really ‘feel’ this 2cm and don’t like it.

I ride my gravel bike like a road bike, with bigger tires. I have some steeper climbs and descents, a few sharp turns I take slowly, but no singletrack obstacles. If a 650bx42 will lower my BB height a couple cm I’ll be super happy, as I really notice the higher BB and don’t like it. So if my initial quest to reduce toe overlap ends up in lowering the BB a couple cm and making me more ‘planted’, that will work out really well.