Campagnolo Record Bottom Bracket Length

[james_from_stoke]

Hopefully somebody who has been around a little longer than I have might be able to give me some advice.

I finally put a set of Record 10-speed cranks on my 10-speed Campagnolo bike (I'd been riding it with some Dura Ace cranks I had lying around, until I could source a spare chainring bolt).
I got the cranks with a 102mm Tifosi ITA bottom bracket, so I fitted that. The chainline in the big chainring is great, but terrible in the small chainring - you can only use the largest 5 or 6 sprockets before the chain starts rubbing against the back of the big chainring. Cross-chaining big/big isn't an option, as the lower jockey wheel doesn't sound happy. That rules me out of using useful gears like 39x15 or 53x21.
I decided to buy a Centaur 111mm bottom bracket. I thought an extra 5mm on each side would be a good move - it's only roughly the width of one sprocket, how much difference can it make?
Now I have the opposite problem - chainline is poor in both chainrings, and even 39x26 sounds rough.

Do I just need to accept that riding in the small chainring will sound like a bag of spanners on anything less than the 17t? I don't remember this being an issue on other 10-speed Record bikes I've ridden.

For reference, the shifting was fine with the Dura Ace 7800 53/39. The Record chainset is also 53/39, and the rings are used but nowhere near worn out. Chain is fairly new Campagnolo. Jockey wheels are fine, cassette is within the capacity of the derailleur. Chainstays are not abnormally long, chain seems to be the right length, 130mm rear spacing.
Any ideas? Is there anyone making a 106mm ITA ISO bottom bracket? Do I just need to ride faster to use the big ring more?

 

[Sm@alite]

I've got round this in the past by using a spacer between the fixed cup and the bb shell . 3mm makes it much better . I'm assuming it's due to Italian bb's being a 70mm shell not 68mm .

 

[Ippikin]

Wondering if your chain is too short? Another couple of links can make a big difference. I have a 10-speed bike with 52/39 and 13/25 so not far off yours, picture of my chain positioned on 52/13 and 39/13 for reference. Ten speed duplicates gears anyway so no need to big/big or small/small with the acute chain lines.

 

[james_from_stoke]

Wondering if your chain is too short? Another couple of links can make a big difference. I have a 10-speed bike with 52/39 and 13/25 so not far off yours, picture of my chain positioned on 52/13 and 39/13 for reference. Ten speed duplicates gears anyway so no need to big/big or small/small with the acute chain lines.
View attachment 995885
View attachment 995886

Thanks for the response
The chain is as long as it can be without hanging slack, and the cage tension is correct. It's a genuine Campag 10-speed chain, so the width is correct.
With the 102mm BB and Record chainset, I can only use the first 5 or 6 gears before the chain starts to rub against the back of the big ring. With the Shimano chainset, I could use all the way to the 9th sprocket before the same issue would occur (not that I would deliberately ride in that gear). With the longer BB, the chainline is just terrible, so that's definitely not staying. I don't know if Shimano used a different chainline than Campagnolo during that period?

 

[james_from_stoke]

I've got round this in the past by using a spacer between the fixed cup and the bb shell . 3mm makes it much better . I'm assuming it's due to Italian bb's being a 70mm shell not 68mm .

I would be tempted to try that, but I'm really weirdly sensitive to asymmetry on the bike – I inadventently rode with a bent saddle for a while, and it really messed with me, took ages to straighten myself back out again. I suppose I could counteract it with a 3mm pedal washer on the other side though. If I can't find another solution, I'll go with this.

 

[Sm@alite]

I would be tempted to try that, but I'm really weirdly sensitive to asymmetry on the bike – I inadventently rode with a bent saddle for a while, and it really messed with me, took ages to straighten myself back out again. I suppose I could counteract it with a 3mm pedal washer on the other side though. If I can't find another solution, I'll go with this.

If nothing else it's cheap and can be undone simply .
Good luck .

 

[Ippikin]

Thanks for the response
The chain is as long as it can be without hanging slack, and the cage tension is correct. It's a genuine Campag 10-speed chain, so the width is correct.
With the 102mm BB and Record chainset, I can only use the first 5 or 6 gears before the chain starts to rub against the back of the big ring. With the Shimano chainset, I could use all the way to the 9th sprocket before the same issue would occur (not that I would deliberately ride in that gear). With the longer BB, the chainline is just terrible, so that's definitely not staying. I don't know if Shimano used a different chainline than Campagnolo during that period?

On mine I can run all the way to 10th with no big ring rub, as such I think a spacer is worth a try. Interestingly I have another bike with Campag 8 speed which did need a spacer to sort the chain line, the q factor was not compromised at all, definitely worth you trying.