CVT Rackmount with CVT?

[heathyoung]

More information - rather than machine off one of the gears on the 7 speed cluster, if I get a 9 speed hub, it will take a 4.5mm spacer, freeing up some room for the sprocket.

Just need to know how close the sprocket runs to the spokes...

 

[5-7HEAVEN]

Are you guys referring to the Chinese "pocketbike engine with transmission" commonly advertised on ebay? If so, it is not a CVT or transmission, but simply a gear reduction jackshaft. The one I purchased had a single gear reduction of less than 2:1.

Any pictures available?

 

[HoughMade]

Something like this maybe?

http://cgi.ebay.com/ebaymotors/CVT-...m14QQhashZitem150297560487QQitemZ150297560487

 

[sparky]

$58 for a CVT... WOW!!

I can't wait to see someone's final MB build with this sucker on it.

 

[heathyoung]

Thats the CVT - an X2. Life would be far simpler if I could mount it on the side opposite the cassette... Grrrrr.... But I'll make it fit

I'm not the first to install one of these on a bike though...

 

[heathyoung]

Well, I had another think about the design, and its very doable with the sprokect mounted on the non-cluster side (on a disc brake hub).

By either extending the output shaft of the CVT, or having the engine poking out the side of the bike (with the attendant weight balance issues - grr) its pretty trivial to mount this up.

A 50cc ebay 4 stroke CHONDA would run this pretty well, to adapt the engine to a 70mm clutch would require a spacer between the engine housing and clutch bell, all the better as it could be mounted through the steel frame giving the engine much needed support.

Failing that, 31cc 4 stroke (which barely musters 1hp ) could be put to better use than the Gebe Knockoff with a 16 tooth (EEEEEK!) drive gear on the bike at the moment (75kph (47mph) downhill at god knows how many RPM yesterday) I also fixed the belt throwoff at >65kph issues (dynamic tensioner) but thats another story.

The brakes scare the **** out of me at those speeds, the front pads started smoking!

A CVT would be great, there is one hill that I have to walk the bike up, very annoying (motor stalls if I try to use it).

 

[heathyoung]

Someone has already done this - the concept is sound

http://au.youtube.com/watch?v=0T0jJkqMfPg

GX35 and an X2 CVT by the looks of it. No pedalling to start off either! Imagine that with a 50cc honda engine... mmmmmmm.....

 

[TWalker]

Anyone have more info on this guy? Can you tell what kind of sprocket that is? It is huge...

 

[loquin]

Oh yea, and to correct one of my previous posts... the compact gearbox is 3.11:1 not 5:1, so my overall gear ratio is 12.44:1 with 20" wheels. Not that it should matter too much in this thread, but oh well...

There may be a problem with a ratio this low...

Per an email conversation I had with an engineer from Comet, if the final ratio is too low, the cvt won't be getting to it's full 'high speed' ratio, which means that the belt will wear excessively. This leads to reduced efficiency, and thus wearing even more.

You 'll end up with pretty short belt life.

 

[heathyoung]

I checked the ratio of the CVT with a few sources - the ratio is correct (that I posted earlier) - the mini-gearbox mentioned is only part of the CVT, not the whole reduction.

With the US dollar being so strong against the AU... I may put this off for a while