Shimano: What is Octalink?

Triathlon Forum
1

I am shopping for a set of 180mm cranks, and on eBay I see a few items that are Dura Ace Octalink. They don’t look like the Dura Ace stuff I am used to seeing. Can anyone tell me the difference between Octalink and “regular” Dura Ace?

Thanks.

2

Octalink is the shimano proprietary spline design for attaching the cranks to the bottom bracket. ISIS is an industry spline design for all of the other cranks manufacturers (FSA, etc). Octalink and ISIS are not compatible. The dura ace with octalink is for the old 9 speed group. However, you can still use them with a 10 speed chain and shifters.

edit You’ll need an octalink BB to use these cranks, not the new 3 piece external BB design of the 10 speed stuff

3

Thanks. I currently have an Ultegra BB on the bike that is 2-3 years old. Any guesses on whether this is more likely to be ISIS or Octalink?

4

It is octalink.

5

If your shopping you might want to consider “upgrading” to the newer outboard bearing bottom bracket and cranks rather than feeling that you have to stick with the octalink bb.Especially if the bb has a lot of wear on it after a3 yrs of use. The newer bb & cranks is supposedly much smoother and better power transfer. You would need to replace both the bb & cranks. The bb is in my mind a consumable item that gets replaced as needed.

Important thing is to make sure whatever you get that the bb & cranks are compatible with each other down the road. Each company FSA, Shimano, Truivati (SRAM) has their own trademake name for the newer outboard bearing bb & cranks. ISIS from what everyone has said in my research isn’t as good as the outboard bb.

I’ve been looking myself since I need to replace my cranks & bb.

Hope you find this helpful.

barb