CVT Rackmount with CVT?

[sparky]

How did you get both chains on the same side?

I cheated and bought this folding bike from fiveflagsmotorbikes.com for $500. It came with the dual freewheel hub. It's a Chinese Tanaka knock-off --> 5:1 reversed, compact (Dax?) gearbox --> 11t sprocket --> 44t freewheel --> hub on 20" rims, dawg... for an overall ratio of 20:1. Next to the 44t freewheel is a standard 12t KMC freewheel which is unusually problematic, tho. I've only taken the back wheel off twice, and I'm pretty sure the KMC freewheel will just spin off... so I'm going to replace that very soon. The 44t freewheel is actually a freewheel that just uses the "clamshell" clamping method to attach any appropriately fitted sprocket (inner hole of sprocket must be proper fit and be able to accept 4 properly spaced nuts & bolts).

Anyway, if you figure out the CVT, gearing, idler gear, etc... just call the guy at FiveFlags and he'll prolly be able to get you a 20" or 26" dual freewheel wheel already laced by itself.

 

[heathyoung]

Thats uber cool. Exactly what I was looking for. With a CVT that would be perfect!

 

[sparky]

Glad to hear it. Can't wait to see what you put together!!

 

[stude13]

hi; i dont get the math--help please. i have an occ chopper and a high zoot 47cc. i ordered a cvt. a range of teeth is availlable. question is if i install a 36 tooth on the rear what should the drive gear be to get 25-30mph.? mitch

 

[sparky]

stude... do you know what RPM the engine is supposed to get?

For example, if it gets 6000 RPM & have a 26" rim...

6000 RPM / (3.15 * 36/x) = ___ RPM * 60 Min = ___ RPH * Pi * 26 In = ___ In per Hour / 12 In / 5280 Ft = ___ MPH

If x were a 5t drive sprocket, you'd get 29.45 MPH, I believe.

 

[sparky]

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...

 

[stude13]

thanks sparky! now to work.

 

[heathyoung]

The compact gearbox is the one on the 49cc 2 strokes that are kicking around on ebay, right? (ie CCW to CW) or the chain drive internals (CW to CW) - the CCW to CW is the one fitted to the drive of the CVT. Ratios still stand for the CVT though.

 

[sparky]

The compact gearbox is the one on the 49cc 2 strokes that are kicking around on ebay, right? (ie CCW to CW) or the chain drive internals (CW to CW) - the CCW to CW is the one fitted to the drive of the CVT. Ratios still stand for the CVT though.

Yes, if staring at a clutch spinning CCW, the gearbox turns the driveshaft CW. As far as I can tell, the ones on eBay are the same... but I remember the sprocket being a bit different from mine. Seemed like mine loked thicker or was for a different type of chain -- a BMX chain.

 

[heathyoung]

Thats Ok, I'm looking at getting one of the "X2" CVT gearboxes (which have a 18 tooth sprocket) and one of the chain reduction boxes (which have the same pitch/keyway etc sprocket, but with 11 teeth) and a 54 tooth sprocket for final drive.

The chain to suit is 6mm wide (internally) with a 11mm between links. Not sure what size that is compared to everything else...

The 7 speed cassette I'll probably remove the 7th speed cog on a lathe or something, and modify the shifter so it wont go into 7th. The 54 tooth final drive will mounted as per the HT drivering (clamped to spokes with rubber isolators) but I will probably countersink the bolts into the drivering - just to reduce the possibility of the drivering interfering with the gear cassette. I decided against flywheel, mainly because I don't know how the CVT will respond, could be very laggy, or risk over-revving the motor.

The mounts on the transmission appear to be rubber vibration isolating, and they appear also to be the engine mounts as well (mounted on the swingarm), so this is also a big bonus to cut down on vibration.

The gearbox is also short, so the motor can be mounted closer to the tyre, to reduce the profile, probably will add a mudguard as well if there is room.

Just need to find an Australian seller of these CVT boxes There is an ebay seller that will ship, but the box is $40, and shipping is $50 (EEEEEP!)

Low range is 32.21:1, high range is 15.47:1 - Very nice

With a 49cc 2Hp 2 stroke, this thing will fly. Pity about the stupid 200W rule. My current motor says 200W, I think I'll use it (31cc 4 stroke).

It will be nice to get the back wheel into a bike rack, stupid gebe pulley doesn't fit the bike racks where I live...