CVT as the ONLY drive

[coachgeo]

maybe its cause of space, maybe its cause most bikes we convert have chain drive already buttt... I dont know.

Why is it we dont put one CVT pully on the engine and just run it all the way to the drive wheel and put the other CVT pully there?

[Crazymanneil]

Are you thinking of a hard-tail something or other? Cos if it is a sprung rear end then the travel of the rear wheel in relation to the front pulley would affect the distance of the centres of the pulleys. I am not overly familar with CVT myself, but would this action not also affect the gear ratio?

unless you could get it so that the pulley was at the pivot of the swingarm which would be an interesting bit of engineering.

I know where you are coming from though, it would certainly shorten everything giving a lot more room for a big hefty engine.

N

[coachgeo]

Are you thinking of a hard-tail something or other?

Some Other

Cos if it is a sprung rear end then the travel of the rear wheel in relation to the front pulley would affect the distance of the centres of the pulleys. I am not overly familar with CVT myself, but would this action not also affect the gear ratio?

Based on me (weak) conceptual understanding of cvt no this would not affect it. An idler wheel could be used to maintain tension though

unless you could get it so that the pulley was at the pivot of the swingarm which would be an interesting bit of engineering.

do'nt think it would be any more engineering than we do now, just different engineering.

I know where you are coming from though, it would certainly shorten everything giving a lot more room for a big hefty engine.

also drop weight due to not needing a gear box and a few other components. In my case. No desire to increase engine size, would just allow for better use of space.

BTW Scooters I believe have one of the CVT pully on the rear wheel. The double conical CVT have been set up to use with Chains. Though have not seen it done..... can't see why the concept they used to make this happen would not work on the type we are familiar with.

Chain Conical CVT shown in below vid around 1'16"

http://www.youtube.com/watch?v=MhFK5gfAGpM

[cumorglas]

BTW Scooters I believe have one of the CVT pully on the rear wheel. The double conical CVT have been set up to use with Chains. Though have not seen it done..... can't see why the concept they used to make this happen would not work on the type we are familiar with.

the scooters you see actually have the engine mounted to the rear swingarm. and they use a splined shaft on the drive pulley. i looked at them very closely hoping to save some space.

cvt's are VERY fussy about center to center distance/belt length. i think an idler pulley would have to be very careful not to affect belt tension since the tension and spring weight and centripetal force are what affects the ratio on the driven pulley.

[Crazymanneil]

hmm, sounds interesting then. Certainly gearbox adds a fair bit of weight and takes up quite a bit of room on the bike. Being able to go direct cvt from engine to rear wheel would eliminate/reduce both these issues...

N

[sbrumby]

Just think about it. They dont go directly to the rear wheel but to an intermediate gear. As an example take the regular enfield, small cog (engine) big cog (clutch) Forget the gearbox for a second, in 4th gear, direct drive, which is small cog driveing back wheel big cog. A CVT does the same job but to have direct drive on the back wheel you would need pulleys probably more than twice the size they are now and they are not what you would call small now.

[UAofE]

With a non-fixed rear end, any movement would affect belt tension and change the drive ratio as if you were changing throttle.