But double reduction might be the way to go with all this. Like a 22:40 coupled to a 22:80 in aluminum. That way you don't have to buy a 192 tooth monster...
Seth
I'm looking to start a discussion about drive pulleys and belts for motorcycles. Here are some things to start us off. First there seem to be 2 major players/suppliers....1) Gates Poly-Chain and2) ContiTech (which I believe are the same folks out of Germany that make the Continental tires)Second there is really nothing unique to an electric motorcycle that would preclude one from using a set up similar to that found on a gas production motorcycle like the Kawasaki 440LTD from the mid 1980s (there are a large number of other examples from production bikes). These seem suitable unless the ratios required for most EVs can not be reached.Third I took advantage of Gates Application Design consulting service (using my 1994 Kawasaki Ninja EV as an example) and their response follows for those of you with time to read it through. You may want to read it from bottom to top to understand the original questions I posed.I appreciate any and all comments.- Mike B.DEVC - ColoradoMike,
There are several potential issues with a belt drive on your motorcycle application:
1) In order to get a 6 to 8:1 speed ratio and keep a similar sized front (driver) sprocket diameter, the rear sprocket would be 18" to 24" in diameter.
2) To get the above diameters, an 8mm pitch belt would have to be used. 14mm pitch belts are the most common pitch on motorcycles, with a few 11mm pitch applications. The larger pitch is valuable in providing not only a higher strength belt, but also bigger/deeper teeth. The larger teeth help the belt avoid ratcheting (jumping teeth). This is important on motorcycle applications, since they usually run at fairly low belt tensions and have center distances that change over the swingarm travel.
3) You mentioned using off the shelf components – the 8mm option would only be available as stock items by using industrial parts. These sprockets will be made of cast iron, and will be heavy and bulky for a motorcycle application. We can make custom sprockets, but there would be a 6-8 week lead time, and an additional price premium over stock sprockets.
4) Without knowing the exact center distance (at rest, full bump, full droop), I cannot tell you if we have a belt length available that would fit (assuming solutions were found for 1,2,3 above). If you can get the center distance measurements to me, I can perform the calculations.
As you can see, there are many significant issues for retrofitting a belt drive onto an existing bike. We usually spend 2 to 3 years working with motorcycle manufacturers for new drives before they are commercialized. Unfortunately, that means that retrofits on existing bikes are usually not practical for many of the reasons above. As much as it pains me to say so, this may be a better application for chain.
Brent Oman
Manager
IGM PT Product Application
Gates Corp.
303-744-4768
From: [EMAIL PROTECTED] [mailto: [EMAIL PROTECTED]]
Sent: Wednesday, September 20, 2006 10:28 AM
To: Oman, Brent
Subject: Fwd: Belt Drive Application Design Question
In a message dated 9/14/2006 12:07:48 P.M. Mountain Standard Time, Mbachandz writes:Hello Brent,
I am trying to come up with a belt drive replacement for a motorcycle application. I would prefer not to resort to custom machining work if necessary for the (I'll call them) cogs required on the drive side and the wheel side.
First to the Gates Poly Chain related question.
The application is a 540 pound street (not race) 500cc engine sized motorcycle, a 1994 Kawasaki Ninja (low power twin cylinder sport bike). This bike has been modified with an electric motor replacing the original gas engine. It now puts out 6 continuous and 32 peak horse power with an estimated 40 to 50 foot pounds of torque. The current chain is a standard cycle chain in the 520 size.
My question related to the belt.....what size belt do I need keeping in mind that clearance related to width may be an issue?
The front sprocket (chain today) is ~3" across and the rear is ~9". The gear ratio is 12t fr to 45t rear. There is no transmission. The front shaft will fit a standard cog sprocket I believe although it may be larger than what I am suing now. The shaft size is 7/8" with a standard electric motor hey of 3/16". Again for the front I want to use standard off the shelf products for cost reasons.
The rear is a standard Kawasaki motorcycle wheel. This may be a harder problem to solve. After some research I find that since the early 1980s a number of mid size Japanese motorcycles including several Kawasaki models have used belt drives (e.g. 1983 KZ440). The ideal solution would be to find a fairly large rear cog from one of these applications. The overall gear ratio that I am shooting for is 6 or 8 to 1.
Please contact me with questions and your recommendations.
Mike Bachand
