Chainlube
Well-Known Member
The only reduction is the 6/44 sprockets.Are you planning to use the reduction gearbox (15:21)? Just looked at it again I see the max hp is at 7500 rpm; so the max no load is at 9000 rpm.
The only reduction is the 6/44 sprockets.Are you planning to use the reduction gearbox (15:21)? Just looked at it again I see the max hp is at 7500 rpm; so the max no load is at 9000 rpm.
So (6\44)>(9\27.5590551181)=22.4555263922\1 TR.The only reduction is the 6/44 sprockets.
No, I don't want to go 35. 20-25 is fine.So (6\44)>(9\27.5590551181)=22.4555263922\1 TR.
(7500×π×27.5590551181)÷(1056×22.4555263922)=27.3834586932 mph
If you don't have steep hills to contend with use an 8t sprocket.
(7,500×π×27.5590551181)
÷(1,056×16.8416447942)=36.5112782575 mph.
If you must use the 6t then change the 44t to a 32t for 35+ mph.
A 6t doesn't give your chain much to wrap around. You could run a 8\60 for a similar total reduction.No, I don't want to go 35. 20-25 is fine.
I did find a couple 1 1/4" BMX pegs in my shop. Something else to think about.
My idea is to have the engine centered on a rack mounted and the roller right underneath. I will run the chain from the little clutch, post #2, to a roller with the 44t on the end. All that on a 27.5" wheel. I just went and measured those pegs, they're 1 7/16".A 6t doesn't give your chain much to wrap around. You could run a 8\60 for a similar total reduction.
Are you talking about using the 1.25" BMX peg like an FD roller (1.25">700c)? That too would give you a similar total reduction like the 6\44>9"\700c
The roller is a 1.4375" and the engine speed is 7500 max, probably more like 6500 cruise speed. The gear box on the engine has a 6 tooth and the drive gear on the roller is a 44 tooth, all with a 25 chain.A 2.8“ roller at 4500 will give over 40mph. I built a direct drive Lifan that ran well set up like that. So you have to balance with the smaller engine the reduction ratio, and the roller size. My recent conversion of the FD to a 5:1 gear box and a 10/44 final reduction (on a 24”) yields 26 ish at 7500. Nice cruise at 22 or so around 62-6500. This is on a 31cc 4stroke. The big 62cc should pull much higher ratios. I can figure roller speeds if you give me the roller sizevand max rpm.
Well, I was thinking of a little push me scooter tire, it has a diameter of 9 1/2". Or, I could just use the hub from the tire and have a 4" roller.It would take a 10” roller at your reduction rpm to achieve 30 mph@7500.;A large slower turning roller is better than a smaller fast one. However fitting such a large roller on a bike is difficult, though I have seem a pic of a build using a lawnmower tire.
Maybe raise the # of the reduction ratio (less teeth on the driven sprocket).