Thalia949

Not sure if this is a C&V question or a repair question, so I will post it here first.

I would like to swap the largest cog on my Campy 8 speed bike from a 23 tooth to a 26 tooth. Will this create any issues with shifting / performance?

I've pulled the cogs off the bike and they all come apart, meaning it is not a cassette in the traditional sense, so it seems like this should be a no brainer, but want to make sure.

thanks!

dddd

Campy's 8-sp stuff just about always handles up to 26t as designed, so only the "B-Tension" screw and a check of the chain length over the largest sprockets likely needs to be fettled with after installing your larger 26t cassette.

Thalia949

Thanks - that is what I thought, but good to benefit from your experience

ridelikeaturtle

If it helps (another data point), I currently run a 13-28t Shimano cassette with 8-speed Campagnolo Record and it all works perfectly.

Spaghetti Legs 

If it’s a Campy branded cassette, there might be a challenge in getting the right replacement cog. There are 2 or 3 iterations of 8 speed cassettes with different notching patterns for the freehub. The first generation freehub in which all the notches are the same size is the hardest one to deal with. The cogs are labeled A thru H to help set up properly.

conspiratemus1

...and, sadly*, you don't just match A with A on every cog. There was a chart, saved but lost when my computer died a few months ago , which showed which letter went on top of "A" depending on the number of teeth on that cog. The first-generation cogs didn't have gates that created an obvious spiral when assembled correctly so you really needed the chart to make sense of it.....Or not. Perhaps it didn't really matter. But anyway, here's the chart resuscitated by Google, in case anyone needs it. I love Campag 8-speed.

Edit: *"sadly" may be the wrong choice of word -- my bad. The virtue of the first generation system was that a cog could be used in any position that made sense, just by adjusting the clocking of the cog with its neighbour (like an Enigma machine.) You didn't need to find a "26A" cog if it was going to be the largest, and a "26B", say, if it was going to be the somewhere else in the stack.

I've got some 26T cogs. You can have one for the price of postage if you can tell me exactly what 8-speed system you have. This Branford Bike resource page: https://branfordbike.com/new-page-1 discusses the various iterations of 8-speed cassette hubs and how to tell them apart. Fully intact 8-speed cassettes (all 8-speeds were loose cogs) were still available on Ebay last time I checked.


The image has been cut off. Under the bottom side of the triangle it should read "Sprocket already assembled" or something like that.

ThermionicScott 

If I'm reading @conspiratemus1's chart correctly, Campy paired a 23T with a 20T or 21T, so you're looking at a 20-26 or 21-26 jump. So it may not shift the best, but who knows? Maybe you can find a way to clock it so it works well.

conspiratemus1

Good point. It would be better to increase the second largest cog, too, so that instead of a (probably) 21-23 as now, you will have a 22-26 for the biggest two. 19->22 will shift easier than 21->26. Note to OP, I can still probably help you, especially if you are using the newer non-lettered cogs with the single indexing mark, which I have more of. If you answer here with what you have, I will PM you.

P!N20

Amen. You have my permission to start a Campy 8 speed appreciation thread.

In the meantime, how are you with indexed DT shifters? https://www.bikeforums.net/21022652-post22.html

Thalia949

I was concerned about the jump from 21 to 26. I was planning to try to use the 23 as the one next to the 26.

I will check what I have a let you know - I appreciate the offer!