CVT CVT's and Comet drivelines

I'm fascinated. I can't quite figure out how the device actuates/selects a ratio. Yes the CVT type is used in some modern cars and was flaunted by Nissan for a new bulky hyped station wagon called a Murano.

I think the design has a lot of merit for small cars and "truckars" (like the VW Golf/Rabbit pickup).

This seems like the perfect choice for a motorised bicycle and possibly some small motorcycles. I would rather have some way to select the ratio though, or to tune the device for the approximate load and acceleration requirements of the vehicle (motor bicycle).
 
I see Hoff Comet are out of business. Is there another source for these type of drives apart from Chineses bikes?

EDIT: Just read the stickty thread on top of page. Please accept my apoogies.
 
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I see the CVT but in another thread you refer to it as a 2 speed CVT. Which is it? I don't see 2 speeds AND a CVT. Also, in the vid (on the stand) it doen't look like the CVT is getting EVEN 1:1. Is there some restriction?
I looks dangerous with all that unshrouded spinning mass. And sorry to bring ants to your pic nic, but in the vids--well let's just say I'd need to see verification of "40ish".
Sorry, not impressed.
 
It is a CVT from Max Torque. I refer to it as a 2 speed auto (sometimes); it is both really. It has a hi and a lo ratio and doesn't hover inbetween it just switches back and forth (automatically) depending on your engine speed.

I believe the reductions are 1.14:1 hi and 3.2ish (I forget) :1 lo. I'm going about 25mph in the drive by vid.

Thanks for the feedback!

I like the open drive and have experienced nothing particularly dangerous.

No Ants at my picnic, it's all picnic I love it, it's really fun. Thought maybe you'd like to see another example of a cvt bicycle. It's ok that you don't like it.

Cheers! Evan
 
It's not that I don't like it. I actually do like it a lot. It's just all the open pulleys that scare me. I'm glad to see someone doing something with the HF blue clone. And anything CVT has my attention. I don't think people know what they are missing out on by not trying to incorporate CVTs in more builds. You are obviously skilled in putting together such things. Oh and the "not impressed" comment is in regard to the 40ish remark, not the build. I'd still like to see verification of that statement. Especially since some on this forum insist that the HF engine isn't capable of anything over 30. PLEASE, prove them wrong!
 
Cool man, no worries!

I'll see what I can do about verifying that speed. Maybe I'll have someone follow me in a car w/ a camera and pan to the speedo. I actually think it'll do better w/ lower gearing 'cause it doesn't rev out all the way unless I'm going down hill. It'll climb 20% grades w/o pedaling though, not fast (maybe 10-15 mph), but it'll do it! So really there is more lo and hi to be had. Another thing to consider is that this CVT is too heavy it could be much lighter and still be plenty reliable. I think w/ the perfect set up this motor will do 45ish. Seems RusticoRay's HF EZ does around that (1 speeds have way lower rotating mass than my CVT). Dan in CT's 1 speed HF WhisperDrive does 35+ too and he's happy w/ that so hasn't tried taller gearing..

I determined the "40ish" on flat ground trying to keep up w/ a friend who has a 70cc 2 smoke shifter w/ an expansion chamber he was reading 45mph and just pulling away from me. So I figured w/ error and everything factored in I had to be going at least 38 mph.

A lot of folks just don't understand this motor, or gearing in general, for that matter. This motor has a linear power curve that just keeps going up the higher you rev it, to a point, but beyond 2.5 hp after the governed 3600 and most seem to rev to 5000+ rpm's w/ no real mods. It doesn't have great low end unless you gear it that way.

As for the pulleys Danger is my middle name. Err ugh I can't really back that up. But really it just looks that way, I'll be making a guard for the bottom left side pulley but the others don't even come into play . A couple of times my pant leg has been sucked into the aforementioned pulley only to be spit out before I knew it (unlike the old pantleg into the BMX chain that'll get stuck and leave you w/ no way to catch yourself). Danger is relative, I guess, I don't wear baggy clothes and I ride aware.

Cheers! Evan
 
Cvt

Cvt Are Used In All The Snowmobiles And New Scooter`s And Some Newer Cars. They Are Basically Trouble Free.

Nuttsy Has Been Riding His To Work When The Weather Permits, In S Florida For Over A Year, Still On The Original Belt. He Started With The 35cc 4 Stroke Then Went To The Hf 52cc 2 Smoke And Is Happy With It.

The Cvt Pulleys Open And Close With Rpm, Starts At About 7:1 Ratio And Smoothly Changes Ratio. You Control The Final Sprocket Ratio With The Rear Wheel Sprocket.

Nuttsy And I Are Using The Pocket Bike Trannys. Firebelly Is The Same Principal But More Heavy Duty. My avatar is a cvt with 49cc cag motor(horizontal piston & cyclinder). Also have a cvt with HS Titan
both are rear rack mount. Nuttsy has his decked out with directional lights etc, looks great. Pic`s in the approx middle of thread.

Ron
 
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TreeWK

Cool man! Checked out those fotos.

Nuttsy, Does the Robin spin CW or did I miss somethin'? Love the "stealth mode"!

Since adjusting the primary (engine to clutch) ratio lower I've noticed gains in take off all the way up to speed. No real increase in top speed but pulls a lot better up to it.

Adjusting the primary does not effect the drive ratio but changes the engine rpm that the clutch engages at.

Contrary to popular misconception the HF doesn't have a lot of low end grunt; it builds power w/ velocity i.e. hp goes up w/ the rpm's.

So moving the motor rpms up in relation to the clutch has allowed me to better utilize the power avail. And, although top speed wasn't noticably increased, acceleration all throughout has been increased and uphill speeds have been increased.

Where the previous range may have been 1500-4000ish rpm's, the new range is more like 1800-5200ish.

Cheers!
 

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