20 inch vs 24 inch wheels

ferball

ferball

New Member
I am building a bike, I was originally gonna go with a 24 inch reaer wheel (that was the donor bike wheel size and wheel) but the donor wheel is a little sketchy. I have a 20 inch BMX wheel that would do nicely. I know the 20 inch will fit my build, but is there noticeably difference in ride quality between a 20 and 24 inch wheel? I am starting to lean towards the 20 inch just for the strength of the wheel, but does a larger wheel diameter make much of a difference aside from less "rolling resistance" if I was actually gonna pedal my bike?
 
The smaller the wheel the smaller the rear sprocket has to be. I have a 20 inch wheel on my bike. I put the manic mech. sprocket adapter on and the smallest sprocket that would fit is a 32 tooth. I can cruise at 30 mph all day long and have pushed it to 35 but don't like doing that. The only way to go faster is the shift kit with some gears. As for the ride, theirs no significant difference.
 
I would not worry about the pedal effort, it isn't like no-one rides a 20 inch bike around. Air pressure and tread design would affect the rolling resistance more than diameter.
Stronger is better.
 
the differences are gonna be a lower center of gravity, which is good, as long as your cranks don't hit the ground when turning (which is bad.)

a smaller wheel will accelerate faster, and like above, a smaller sprocket will keep it from over-revving and winding out. if you put the stock 40-something tooth on, it'll take off like a rocket, but max out pretty quick.

if you keep the front 24, it'll change the steering angle. it's like adding a raked fork, since the back end is now lower. this'll actually help at higher speeds. it won't turn as sharp or be as twitchy.

and if you have rear V brakes or calipers, they won't fit anymore.

bottom line, is if it fits, and it's comfortable to ride, it'll work.
 
I mocked up the build today, I may have an inch of ground clearance with a 20 inch, though I am liking the idea, it may mean welding on some new drop outs.

Is it possible to but a rear shimano cassette onto a bmx wheel? Haven't looked at it yet, but I am sure someone here knows the quick answer.
 
i have been entertaining the idea of a 20 in. ride. i would think the thing would handle great. i just want a good range of power from the start and top end speed
 
adb140275 said:
24 inch wheels are 4 inches larger than 20 inch wheels
Click to expand...

that's not entirely true.

a 24" rim, for example, isn't 24" in diameter. it's closer to 22". it's the tire diameter that makes up the difference.

but...

a 24x 2.125 tire is close to being 24" in diameter, but it's not exact.

a smaller tire, say, a 24x1.75 tire is closer to 23.5, and an even skinnier tire can bring it down even smaller.

so you can have a so-called 24" bike with tire diameters of 22.5"

by the same token, you could get a 20" wheel with a 20x4.0 tire, and it'd be close to 24".

y'know, if you wanna get technical about it...:)
 
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bairdco said:
that's not entirely true.

a 24" rim, for example, isn't 24" in diameter. it's closer to 22". it's the tire diameter that makes up the difference.

but...

a 24x 2.125 tire is close to being 24" in diameter, but it's not exact.

a smaller tire, say, a 24x1.75 tire is closer to 23.5, and an even skinnier tire can bring it down even smaller.

so you can have a so-called 24" bike with tire diameters of 22.5"

by the same token, you could get a 20" wheel with a 20x4.0 tire, and it'd be close to 24".

y'know, if you wanna get technical about it...:)
Click to expand...
I just went to School on the 24 inch wheel. It is roughly 19.96 bead to bead on the tire. Just rechecked with a tape measure. Was looking for a Heavy Duty 2.55 mm wall thickness tube for one. http://motorbicycling.com/f53/24-x3-0-true-heavy-duty-27659-2.html
 
yeah bairdco, a 20 inch bicycle wheel is THE SAME size as a 16 inch moped wheel... as in 20 inch bicycle tires fit on a 16 inch moped/motorcycle wheel.

why do they do this? the unit of inches is a constant...
 
going fast on a smaller bike is more fun as well. doing 40+ on my 24" is a lot more scary than doing 40+ on my 26.
 
check my album on my profile and look at the orange bike "LO-PED" 24/20 with bmx cranks off a 16" kids bike, built this last september. 44T rear sprocket

Great on gravel downhill, riding position (and uphill low gearing)

Great around town, beats every car at the lights

Not so great for touring, makes for a slow trip.

Oh, and as mentioned earlier, front 24" rake is very nice handling

It's hard to get smaller kit sprockets here, but am onto a 28T bmx chainring to mod and fit, next couple of builds are 24" Front and rear, and a 20/20 cruiser...

So.... depends what you want to do on your bike.
 
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