CVTs

[arvind61093]

CVT(continuously variable Transmission ) is gaining popularity because of its fuel economy and smoothness. Companies like Nissan have been using this technology in their cars now.

It's usage is being developed for motorbikes as well.

I m working on a project to develop a CVT for bikes .

Can anyone give me an idea about which type of cvt(pulley or toroidal or hydraulic) will be suitable economically and considering the space limitations in a bike

[shorod]

I'd suggest you start by checking out the CVTs that have been used in snowmobiles for years. They would be interfacing with similar engine sizes as what you are trying to accomplish, as well as similar space constraints and power.

-Rod

[MagicRat]

Originally Posted by shorod

I'd suggest you start by checking out the CVTs that have been used in snowmobiles for years. They would be interfacing with similar engine sizes as what you are trying to accomplish, as well as similar space constraints and power.

-Rod

I understood that the OP is referring to bicycles. But his post is vague and misleading on this point.

FWIW, belt-type CVT's have been used for motorbikes for many years, mostly for the older-style minibikes for kids. I have ridden quite a lot of these, and they work okay. Their biggest problem is the primitive engineering of the entire machine, and not the CVT itself.

[shorod]

Now that I re-read the OP I agree, he's talking bicycles.

There is an "autoshift" bicycle on the market, but it is not CVT.

Considering how relatively slow the typical cadence is on a bicycle, it could be quite a challenge to implement a CVT on a bicycle. Plus, not ever rider will want to maintain the same cadence as the next rider, so that would need to be adjustable as well. It seems like a CVT for this type of application would require a pretty elaborate weight system or electronics.

-Rod

[MagicRat]

Originally Posted by shorod

Now that I re-read the OP I agree, he's talking bicycles.

There is an "autoshift" bicycle on the market, but it is not CVT.

Considering how relatively slow the typical cadence is on a bicycle, it could be quite a challenge to implement a CVT on a bicycle. Plus, not ever rider will want to maintain the same cadence as the next rider, so that would need to be adjustable as well. It seems like a CVT for this type of application would require a pretty elaborate weight system or electronics.

-Rod

One could use a traditional dual pulley system with manually -adjustable weights. The weight's spring tension could be manually adjustable, using a simple twist-grip adjuster. Dial up the tension and the CVT would reduce the rate at which cadence increases as the pedaling force increases.

The challenge would be to design an ultra-low friction pulley system to maximize efficiency.