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View Full Version : Chain managment - Rear jackshaft - problem with front derailer



PaulPb
12-12-2010, 09:08 PM
Hello;

I'm working on a tadpole that has a 'rear jackshaft' -

I was able to get the gears to work in the back.

But I haven't yet been able to get the fr. dr. to work-

Do I need some type of 'chain tensioner' (like on a rear derailer)?

here are some pic's

Radical Brad
12-12-2010, 09:10 PM
Nice work!
Looks like you will require another derailleur for the rear, just under the jack shaft.

Brad

PaulPb
12-13-2010, 04:26 PM
The rear works fine - my problem is getting the front derailer to work

PeterT
12-13-2010, 04:58 PM
If you placed a secondary rear derailer under the jackshaft, like you have on the rear of the bike, that will adjust the tension on the front chain and make it easier for the front derrailler to work properly.

PeterT

John Lewis
12-14-2010, 07:41 AM
Looking at your setup, the rear deraileur is taking up the slack in the chain as you move from gear to gear so thats fine.

When you move ring to ring on the front you have nothing to maintain the chain tension.

You need at least the spring part of a rear derailer or perhaps a spring loaded jockey pulley to take up slack. A derailer would be easiest.
It can be fixed position or if the jockey cog is a rear cluster style you could get extra gears.

John Lewis

PaulPb
12-14-2010, 07:49 PM
Do you mean the part of the derailer that the chain passes through? ( 0\0 ) - or the whole rear derailer?

{0\0 = rear derailer removed from spring loaded adjustable part.}

and would you put it close (towards the front ) under the jackshaft? - or in my case somewhere between jackshaft and second pully(?).

Or minus the second pulley? -

Paul

AtomicZombie
12-14-2010, 08:40 PM
http://www.blackbirdbikes.com/images/ez1e4middrivemotor1_001.jpg

Brad

PaulPb
12-15-2010, 05:12 PM
OK

I'll try it -

I have to see if I have a rear derailer that isn't taken apart - or that I can put back together.......

thanks; Paul