HT 3 speed proposal

[2strokepoke]

i was thinkin.. it may be possible to use the original 9 hole 44 tooth sprocket with some smaller sprockets i have laying around a 25 and a 36 though.. the 25 is probably too small and too big of a jump might have to dig around for a different one. i was thinking if i used longer bolts and drill the 9 holes in my sprockets and space them out a bit... might be able to get a 3 speed drivetrain goin.. how to make it switch though is a little outta my ballpark. it would take me alot of thinkin.

anyone have a similar setup or idea?

 

[Neon]

This has been brought up more than once. I like the idea myself but seems to be a hard job to get working. Lots of little problems get in the way, like keeping steady tension on the chain when going to smaller sprockets. In the end it just seems easier to go with an SBP shift kit.

 

[motorpsycho]

the major thing is that the chain would have to stay completely in line the whole time.
any slight variation in the chains alignment will throw the chain off the sprocket.
if you are thinking of using a derailer type set up, it probably won't work because it will move the chain to the left and to the right too much while trying to shift (throwing the chain off).
and then as neon said, you would have to figure out a way to keep constant tension on the chain so it never gets too tight or too loose.
I'm not saying that this whole idea isn't possible, i'm just saying that it would be pretty difficult to make something like this work right without having the chain come off and lock up the rear wheel.

 

[2strokepoke]

i was thinking of using a front deraileur since those are designed for 2-3 speeds

 

[HeadSmess]

it would be possible, a chain can tolerate some misalignment over a distance, else a normal pushy wouldnt work at all...

purpose made shifter, a left handed, extra heavy duty derailleur. what ratios proposed? on a 20 inch rim is easier as the sprockets are smaller and a change in say 4 teeth a time makes a larger difference to the overall ratio...

then while the heavy duty bmx chain worked ok on my unmodded engine...would it cope with the one im running now?

so, therefore, could 415 chain deflect enough to stay on the sprockets but change too?

i think its possible...even if its only a 2 speed...

gimme a few weeks

 

[2strokepoke]

let us know how it goes. Do you think an 8 tooth jump is too much?

 

[max350]

It is a fairly simple modification, you can read about it in my building on http://motorbicycling.com/f42/my-bike-project-17995.html. it works, but you should have a wheel that can handle the extra weight that will be of two pieces of rear sprocket