Did campy change their chainring bolt diameter?

[fmradio516]

Originally Posted by Mark McM

Okay, I've been doing some digging around in the Campagnolo Small Parts catalog and I think I know what's going on.

The original 11spd 135mm BCD cranks used chainrings with the traditional sized bolt holes (12mm/10mm). Aluminum cranks used traditional 10mm chainring bolts, and the carbon cranks used the bolts in the picture above to step the bolts down to 8mm in the middle.

But for 2011 to 2014, Campagnolo changed the chainrings to us a straight 8mm bolt. The outer chainring apparently had an 12mm/8mm bolt hole, and the inner chainring had a threaded 8mm hole, so that the bolts screwed directly into the chainring (I've heard of these, but haven't actually used them).

So, it looks like you may have a 2011-2014 outer chainring, but 2010 or earlier bolts (and inner chainring). So you may need to get a new outer chainring of the right type/vintage. The other option would be to get new bolts plus a new inner chainring.

The part numbers for are as follows:

2010 and earlier:
52 tooth chainring: part no. FC-SR052
39 tooth chainrng: part no. FC-SR039
chainring bolt set: part no. FC-SR100

2011 to 2014:
52 tooth chainring: part no. FC-SR152
39 tooth chainring: part no. FC-SR139
chainring bolt set: part no. FC-SR200

Thanks so much for digging into that! These part numbers will come in handy!

[jimoots]

Originally Posted by tanghy

get a new inner ring and the matching bolts, this happened to me too.

Yeah this caught me out too. I thought it was 10sp vs 11sp (I accidentally bought 10sp TA rings) but it sounds like there are 11sp rings out there with the pre-2011 designation, too.