Bicycle Mechanics - Campy 8-speed Ergo drivetrain, Shimano 7+1 cassette, slight shifting problem.

Hi all.

I have restored an Olmo with full Campy 8 speed (Ergos) drivetrain.

To ease the load on the wallet a little, instead of buying a Campy clincher wheelset I used a Shimano wheelset with a 7 speed 13-23 Shimano cassette, plus a 26 tooth 7-speed sprocket and spacer. AFAIK this should all work perfectly because the spacing (sprocket+spacer) of Shimano 7- and Campy 8-speed are the same, 5mm.

Everything works fine, apart for one thing. In the small chainring (39) the 4th sprocket skips. Above and below it, all is well.

I realised the FD was rubbing slightly on the chain (I hadn´t trimmed it properly, not used to Campy) and that got things a little better, but it still ain´t perfect.

So to recap, on the big ring all is well. Likewise, on the small ring - bar the skipping 19-tooth sprocket. The RD shifters smoothly in both directions and seems well aligned. The chain is the correct length.

Any ideas, anyone? I want to try and avoid making it any worse!

Here´s a pic taken before I put the chain and cassette on:

http://i.imgur.com/FT9HI.jpg

1. Campagnolo recommends that in setting up the shifters you start in the 'middle' cog in the rear (on 8s that'd be #4 from the small end), and set the derailleur/cog alignment to be perfect on that cog. It's worth a shot if you didn't do it this way.

2. Which rear derailleur are you using? When I tried setting up 8s Ergo using the earlier Chorus model with the A/B adjustment I was never happy. It all went smoothly when I bought the next version. Your's looks newer, but I can't really tell.

3. My 8s setup was also happier with a Campy C9 chain than the SRAM 8s I started with.

1. Ah, ok, didn´t know that.

2. No idea, this is the first bike I have had with Campy.

3. It has a 6/7/8 speed KMC chain with a quick link. I have cleaned and relubed the old Campy chain but a) putting an old chain on a new cassette is bad practice AFAI am aware, and b) I would like to keep the KMC on if poss.

Thanks for the quick reply.

Ex Pre, I think I know how to set up the 4th sprocket, but can you talk me through it anyway?

Do you set up the small sprocket first, click up to the 4th, see what it's like, if it's not perfect relase the cable tension, then move the RD inboard/outboard on the small sprocket, retension, click back up and check again? Or am I being an idiot and missing a more obvious way of doing it?

Thanks in advance

Also in addition often times you'll see it skipping or chattering in the middle gears when the tension is slightly off on the derailleur.

You should already have your limit screws pre-set. Go ahead and start on the small sprocket. Before you tighten the cable, give yourself a little 'wiggle room' on the adjusting barrel - turn all the way in, then back off about 1/2 turn. Then you can pull the cable tight and tighten the clamp bolt. Click on up to the 4th cog. From here you then use your adjusting barrel to get the derailleur lined up on the sprocket perfectly. Shift it up and down, recheck your limit adjustments, your b-screw position, and if all is well this accomplished something. Good luck.

OP, can you update us on how this turned out? I'll be finishing off a build with a very similar setup, and am curious if you got this to work.