timk_

Hi guys,

First I must say this looks like a great resource you have here.

I have a 2008 Giant OCR 3 and I am wanting to fit a mid drive electric kit which has a 44T crank. The rear derailleur is an "RD-2200" (low end) and the bike currently has a 12-26 rear cassette with a triple setup on the front.

I was wondering if because I am going to a single at the front, could the RD stretch to a max sprocket size of say 30 or 32 if I wound up the B tension a bit?

The plan is to fit a SRAM PG850 11-30 or 11-32 cassette. The freehub seems to be the compact type so the 11 sprocket should be okay, but can I tell visually if the existing lockring will work?

Cheers!

Bill Kapaun

It doesn't look like it.
RD-2200

Just get a low end Mountain RDER and the problem is solved.
Something like an RD-M360

timk_

Thanks Bill, I had come across their documentation but that figure seems fairly conservative?

I was hoping someone had tried this particular RD with something larger than a 26T. The cage length is 64mm which is kinda weird. Come to think of it I could borrow the 32T cassette from my MTB and try it!

Also disregard my question about the lockring, I had forgotten they come with the cassette not the freehub.

When I get a chance I'll try out my theory with the B tension screw and will report back!

dsbrantjr

The cage length relates to the maximum chain wrap; the max cog is more a function of the geometry of the parallelogram and how the springs and jockey wheels interact. And going from 26T to 32T is a big jump; you might be able to push a derailleur a couple of teeth outside of its stated range but 6 is usually a bit much. As Bill Kapaun suggested, an inexpensive (or expensive if you want) mountain RD will do the job nicely without pushing any limits.

Andrew R Stewart 

I find in this thread the mid drive adaption the FAR more interesting elephant in the room. I hope the OP supplies us with photos of his efforts along the way with a follow up after completion. Andy.

timk_

Fortunately, winding in the B tension screw has achieved what I want with my current RD-2200 derailleur:





That's a 12-32 cassette fitted. I just got back from a test ride and it still shifts really nicely, it is however right on the limit of the B tension screw (it's screwed all the way in).

Please excuse my weathered chain, I only just bought the bike.

Andy, I will post up some more pictures when I get the build started!

Cheers!

timk_

I just chucked it back on the stand and wound it out a few turns, now the teeth are sitting about 2mm apart. I'll report back if it gives me any issues!

Squeezebox

I'ld like to hear about the mid-drive elect kit. Is it possible to use a rear tandem crank? That way electric power on the left timing chainring and keep the right side chainrings as normal bicycle stuff?