speed? torque?

[mike75925]

alright, i know power is the biggest factor in speed, but, bicycles have large sprockets for the engine (us) and small on the wheel. they came out with a bike a few years ago that would do 215, carbon fiber, silk tires, helium inflated, and a huge crank sprocket (say 18"). my question is would we not benefit better from large engine sprockets and small wheel/axle sprockets? granted kart tires other than junior drag are not made for those speeds, but we could run atv, motorcycle, scooter or other tires, some of which are cheaper than the kart tires.

 

[EagleTalons]

Play with the speed calculator a bit and see the speeds.

 

[mike75925]

i did, but i'm wondering if there will be more torque? we, ourselves, can propel a bicycle to 70mph. what then would happen if we produced 5hp? what would that equate to? a top fuel dragster? oh wait it takes our weight to get the pedals around plus some on a hill, we would have to re-tune our engines for torque versus speed. who knows how much torque these things put out?

 

[EagleTalons]

Also we operate at a very low rpm range.

 

[modelengineer]

Human beings can generate a lot of torque on pedals, but I've read that the maximum output for a very fit athete is about 1hp for around 1 minute, then it decreases.

If you put such a tall ratio on a combustion engine, particularly the small ones we usually see here, then it just won't have enough torque to accelerate. You won't go anywhere. Try it!

 

[BradenM]

Smoke dat clutch boi!

 

[Affair_driven]

my question is would we not benefit better from large engine sprockets and small wheel/axle sprockets?

Try driving a car from a standing start with overdrive only, or riding your 10 speed bicycle in 10th gear only. See the problem?

 

[Rotore]

build your engine to handle 6000rpm, supercharge it and try it from there because a 5hp wouldnt cut it for those ratios but bmx bike do have a ratio like 1:3 or 1:4