OP
OP
Merida man
Regular
Are there any problems with reducing the size of the from chainring from 39 to 34
Campagnolo Cassette/Rear Derailleur compatibility
- Thread starter Merida man
- Start date
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Smokin Joe
Legendary Member
- Location
- Bare headed cyclist, Smoker
You can't do it, 39t rings need a Bolt Circle Diameter (BCD) of 130mm and will only take a ring down to 38t. You'll need a compact chainset.
Ajax Bay
Guru
- Location
- East Devon
You have not shared what crankset you have. Need to confirm this (?Veloce) before answering the question authoritatively. Campagnolo standard BCD is 135mm and smallest chainring is a 39t.
Compact (ie with a 34t): https://www.campagnolo.com/UK/en/Components/veloce_crankset
Probably better off (vfm) with a non-Campagnolo compact chainset: the chain, derailleurs won't notice: get one which can use the current BB or buy a new one: they are inexpensive.
2old2care
Über Member
How much difference would 0.21 of a mm make?
2old2care
Über Member
Isn’t that what I said ? Sort of.Campag don't really do low bottom gear cassettes. Too cissy for those macho Italian men.
Your best option might be to find a triple front chainset but might be pricey, plus you'll need new FD and shifter. No, forget it, cheaper to lace a new Shimano hub and use their cassette. You can keep the RD.
winjim
Smash the cistern
The question is how much difference would 0.84mm make, since if you align it on the centre sprocket you've got four sprocket's worth of distance to travel in either direction.
If you really want to use a Shimano cassette you can take it apart and swap the spacers for Campagnolo ones since the sprockets themselves are the same width. Might require some force and a punch if the sprockets are pinned together.
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Yellow Saddle
Guru
- Location
- Loch side.
The difference between index shifting and friction shifting, because if you align the chain with the smallest sprocket during set-up, as is custom, you'll increase the error for each subsequent sprocket by 0.21
2nd gear, 0.21mm out, 3rd gear, 0.42m out, 4th gear, 0.63mm out and so on.
In real terms this means only the default gear and the one next to it may give you any sort of gear, thereafter it is clatter and jumping and swearing.
Just accept it, it doesn't work.
Ajax Bay
Guru
- Location
- East Devon
@2old2care : "Get a Shimano wheel and a Shimano cassette. The nine speeds are the same spacing for Campag and Shimano, so should work."
Yes, you reiterated what @Cycleops had already suggested (and which had been already contested as 'not compatible'). His advice was as useful as yours, in this instance.
- Location
- The TerrorVortex
[Mod hat]
I've fixed the typo on the thread title
[/Mod hat]
I've fixed the typo on the thread title
[/Mod hat]
slowmotion
Quite dreadful
- Location
- lost somewhere
If you want to search for some smaller chainrings, Spa Cycles is a good place to look. Just be sure to check that the bolt circle diameter will match.
https://www.spacycles.co.uk/
https://www.spacycles.co.uk/
Ajax Bay
Guru
- Location
- East Devon
Agreed, and a TMN award to @boydj
Point (of the thread) is that one can 'look' but the OP's crankset can't take a chainring any smaller than their 39t.
