flangeflange

This is a hard one. I want to replace the B-screw plate for my early 90's Deore XT rear derailleur. It came with a bike that has the full related groupset, so I'd rather keep it original if I could. Unfortunately these particular derailleurs are expensive on the second hand market.

It seems that the tab with the B-screw on it has broken off -- it was bent quite sharply inward, and it snapped off when I tried to right it again. It wasn't even my negligence -- it just snapped in the way that metal tends to do after having been bent back and forwards a few times. So I need a replacement for the little plate which is normally clamped into the spring mechanism with a C clip.

I've tried a few different (broken) derailleurs to see if their parts work. Tried a very similar looking Altus C20 but the plate was much too big. Tried a much more modern Deore RD but that also didn't work. It was worth a try.

Does anyone know where I could source one of these? Or know of compatible products -- i.e. any other derailleurs with compatible parts. I suppose the last choice is to buy a new one, but it seems such a shame to ditch this one just because a tiny tab of metal has been broken off.

Here's more info -- https://velobase.com/ViewComponent.as...1a970&Enum=108

Andrew R Stewart 

I think that finding an old der with a compatible plate will be your best chance. The upper bolt assembly was at one time made available separately. But I only know of one shop in my town that stocked them and we didn't try to continue this for long. (No turn over rate that justified restocking, selling a complete der made so much more sense and was a more total solution to a worn/broken der). Andy.

flangeflange

I wouldn't know where to start. Well, I might have to try a local bike recycling place because they have a whole heap of old derailleurs.

Is there anywhere that has this kind of info available? All I can say about it is that the plate's diameter is definitely much smaller than the other mechs I tried -- Altus C20, modern Deore (early 2000s) and a yellow label 105.

Velocivixen

@ flangeflange - Not sure where you're located, but a bike coop would be my first choice. Coincidentally, I was at a local bike swap/street fair yesterday in Portland and bought that exact same derailleur for my bike for $25, in perfect condition. I have found very small, esoteric parts by scrounging through bins at my favorite coop in Portland. It's amazing what you might find.

the ones I've seen on ebay weren't too expensive, but I suppose that is relative. Good luck. I'd be interested to hear what you come up with.

Hendo252 

Short term: buy any RD that will do, new or used.
long term: keep an eye out for a good M735 on eBay, boards like this, etc.

that at way you are back on the road soon, and can wait for the right deal to come along.

flangeflange

Velocivixen: I practically live in the local bike charity -- I'll try to move my bones down there tomorrow. They rarely have quality rear mechs though -- the mechanics there are likely to keep those to one side for repairs.

Hendo: Actually managed to pick up a Tiagra front and rear mech (RD and FD 4400) for £13 delivered.

https://www.dropbox.com/s/krqlg99i75klov0/IMAG0039.jpg -- this is the bike it's going to go on. I was inclined to keep it all period, but I'm not really a purist in any sense. I'll use what works. The drive components need replaced on that bike anyway. I just hope the biopace rings haven't suffered too much -- they look alright to me. (Rings -- https://www.dropbox.com/s/v39m0lxjbh...9_BURST007.jpg -- pre-cleanup after purchase)

The M735 just feels like a good quality mech. Shame if I can't fix it.

Velocivixen

On a slightly different note, flangeflange, how do you like your Biopace? I recently bought a 1992 Specialized with them & don't really notice any different sensation when I ride.

flangeflange

I like them. I've got two bikes with Biopace -- the Romany in the picture and a Raleigh Elan from around the same era, early 90's, with a 300EX groupset installed.

I find the required torque feels consistent through the whole rotation of the pedals, whereas with a round ring I feel an ever so slight drop off around the 6/12 o'clock positions. Hopefully that's not gibberish, and doesn't sound like a placebo effect. I do notice a difference anyway, whatever it is, and I like it.

It is more noticeable at low-RPMs, so try a hill slowly and see what you think.