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-   -   Questionable shifting into smallest 2 cogs (Campy 8sp) (https://www.bikeforums.net/classic-vintage/815731-questionable-shifting-into-smallest-2-cogs-campy-8sp.html)

whatwolf 05-04-12 01:13 PM

Questionable shifting into smallest 2 cogs (Campy 8sp)
 
Hello all.

I bought this awesome Merckx bike last week from one of my friends. It was built up by a friend of his with Athena shifters, crankset (53/39), and brakes, Veloce 9sp derailers, Dura Ace hubs, SRAM 8 speed cassette (11-28). It shifts flawlessly through the middle and low ends, even into the big-big combo (53-28).

But I noticed that the spacing between the 11T cog and the frame was very tight, a couple mm at most, and the limit screw on the Veloce RD was set up so that it would not shift into that cog at all. To see if the chain would even fit there, I adjusted the limit screw and shifted into the 11T cog -- it sort of worked, but it doesn't sound right. In fact both the 11T and 12T cogs sound unpleasant, but I can't see what's rubbing where. It certainly looks as though the chain clears the frame (but only by a hair.)

So for now, I only have a 7-speed (albeit a wonderful 7 speed). I am wondering if there is a different way to space the hub/dish the wheel that would fix this? Or something else that I am not thinking of? This is my first time dealing with anything more than a 7 speed FW.

I took some pictures that hopefully show what I'm talking about (note the spacers on the NDS).

I have eventual plans to upgrade the drivetrain if it seems like a good idea down the road. For now I just want to ride, but I have been sitting at home sick this whole week just staring at it and thinking of ways to make it even better. Getting the shifting right would definitely help.

http://i302.photobucket.com/albums/n...erckx-RD-1.jpg

http://i302.photobucket.com/albums/n...erckx-RD-2.jpg

http://i302.photobucket.com/albums/n...erckx-RD-3.jpg

Apologies for the grime!

Ex Pres 05-04-12 01:24 PM

SRAM 8s spacing /= Campy 8s spacing. The best way to make this combo work is to adjust for best alignment in cog 4-5, and so by the upper and lower cog you're off by just under a mm (short on each end). That's the best you're going to get with this setup.

Also, chainstay interference can (doesn't always) happen when you take a 126mm frame and use a 130mm wheel in it. Been there, done that, went back to 7 speed.

whatwolf 05-04-12 01:27 PM

Well that's good to know, I was surprised to find out that the cassette was SRAM because it really does shift well from the 3rd cog inward - does that have to do with the 9 speed derailers?

whatwolf 05-04-12 01:35 PM


Originally Posted by Ex Pres (Post 14181499)
Also, chainstay interference can (doesn't always) happen when you take a 126mm frame and use a 130mm wheel in it. Been there, done that, went back to 7 speed.

Yeah, I took out the wheel to see what the natural spacing of the rear end was and it didn't spring back. Measured it at 130mm. Could have been cold-set, I suppose (I'll try to find out), but it could also just be a 130mm frame. The flat crown fork and TT cable guides made me think it was an earlier frame, but I'm pretty sure it's 90/91ish?

Ex Pres 05-04-12 02:32 PM


Originally Posted by whatwolf (Post 14181512)
Well that's good to know, I was surprised to find out that the cassette was SRAM because it really does shift well from the 3rd cog inward - does that have to do with the 9 speed derailers?

I can never remember if the "9 speed" label on a Veloce level derailleur means it pre-2001 cable pull or post, but I think it means pre, so mixing of that 9s derailleur with an 8s shifter is not a worry as they were both designed for the same cable pull ratio. (I am assuming the shifters are old 8s)

jebensch 05-04-12 05:09 PM

This page on compatibility between Campy/Shimano/SRAM is illuminating. I'm dealing with 8sp Ergo woes as well. Jumping cogs, rattling on the low gears. Might have to do with the pounding I put on the brifters' innards to get the jammed non-Campy cable heads out. :(

rccardr 05-04-12 05:44 PM

Put a 1mm spacer between the end of the axle nut and the frame, adjust the limit screw & cable tension and it should work just fine.

whatwolf 05-04-12 06:32 PM


Originally Posted by rccardr (Post 14182354)
Put a 1mm spacer between the end of the axle nut and the frame, adjust the limit screw & cable tension and it should work just fine.

If it works, this would be the simplest (and cheapest) solution. I'll give it a shot. Have you dealt with this campy/shimano/sram combo in the past?

whatwolf 05-04-12 06:40 PM

I have the opportunity to buy this wheelset... I suppose I would then also need a newer rear mech (diff. cable pull?) and shifters? Or one of those spacer kits to use 8s cassette on 9/10 hub? But I digress.

I wonder if the Rolf would look terribly out of place on the Merckx.

http://images.craigslist.org/5Z45H55...d961331b45.jpg


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