Homeade 2 speed Idea..

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copmagnet80cc

copmagnet80cc

New Member
Jan 7, 2014
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Ohio
Ive had an idea for a shift kit but havent really had the time to ever try it yet. But I was thinking how normal mountain bikes have the gears on the back wheel...now what if we spaced out a 44 teeth and then maybe a 36 teeth sprocket together and used a similar shifter like mountain bikes do. So all you would have to do is when you get up to speed is shift and with a spring chain tensioner keeping everything nice and tight with the shift...anybody follow me on this??
 
M

mat_man

New Member
Jan 29, 2011
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athens ga
Hi CM80

You can buy a $15 rear derailleur that can do 36 teeth max, but to shift larger sprockets it
becomes much more expensive using a rear derailleur. If you reduce wheel size you could use
smaller sprockets and get the same ratios.

You might could somehow use a front derailleur as a rear shifter.
 
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2door

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
This concept has been discussed here before. The big problem you have to overcome is chain/sprocket misalignment. Bicycle chain made for use with derailers and the sprockets are designed to run a little off kilter and allow the chain to slip on and off of the sprocket teeth. The engine drive system won't be quite as forgiving.

Off setting the engine drive sprocket to the rear driven sprocket will usually always result in poor chain performance, derailing, etc. Spring loaded tensioners are frowned on by a lot of experienced builders because they allow slack in the chain when you least want it.

I'm not trying to discourage you from giving the idea a go, but just making you aware of some of the hurdles you'll have to overcome.
Good luck. Let us know if you get something to work. Would be a great idea.

Another option would be a system where you could switch between different driven sprockets but not on-the-fly. You'd need to stop and physically derail the chain and move it to the other size sprocket. That would mean using an adjustable tensioner to take up the slack when you're on the smaller sprocket. However you're still faced with sprockets that aren't properly aligned.

Tom
 
Sidewinder Jerry

Sidewinder Jerry

Well-Known Member
Dec 19, 2011
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Rockwood, TN
Not exactly sure what you're talking about. The Staton Inc shift kit allows you to have 3 chainrings to drive the rear gears. Here is a Staton setup I like to do for a 24 speed bike: 18.75:1 gearbox; GB-SK 15:44; rear 8 speed DNP freewheel or cassette (34,28,24,21,18,15,13,11); chain rings(28,36,44). Shift patteren 1(1,2,3) up steep hills towing. 2(3-6), 3(6) level ground. 3(7,8) over drive down hill. The only time you shift the front chain rings is when you're in 3 or 6 in the rear. Before stopping going up a steep hill be in 1(1) then use that as a starting gear. For all other stops be in 2(3) before stopping then use that as a starting gear. This systems gives you 10 easy to understand gears. It eliminates gear redundancy, cross chaining and chain droop.

I either use a thumb throttle with 2 twist shifters one on each handle bar. Or use a twist shifter for the rear gears and a thumb shifter for the front chain rings. I the mount the shifters on the left handle bar and put a twist throttle on the right handle bar.
 
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