12-25 or 12-27

Which cassette do I need for my tri-bike? I train in relatively hilly conditions, but race in all types of terrains (i.e. IM Florida and IM Lake Placid). Is there a big difference between these two cassettes anyway?

12-27.

If you ride Campy you can get a 26. The extra bail-out gear is always nice, even if you don’t use it all the time.

50/36 + 12-25 or 11-23.

I disagree. Shifting is much smoother (at least with Shimano) with a 12-25. You can always keep a 12-27 handy for those really hilly rides, but the 12-25 is better overall for most people.

depends on the combo and what you ride.

standard for me is a 12-23, I’ve ordered a 11-23 for more top end. these are all run with my 50/34 compact.

I have an 11-21, 12-25, and a 12-27 so I can really dial in for the course.

Depends ™.

What size rings do you run in front?

Are you a spinner or a masher?

Are you a strong climber, or not?

Do you run Shimano or Campy? 9spd or 10?

FWIW, I have 9spd Shimano, and have 12-23, 12-25, and 12-27 (thanks again J-) cassettes. They all work fine. (Only time I ever ran the 12-27 was at the SBR Harriman Half, and I was happy to have it then.) I train on the 12-25, and usually race on that or the 12-23, depending on terrain.

<< Is there a big difference between these two cassettes anyway? >>

The ONLY difference in 12-25 vs 12-27 is the last 2 largest rings. Otherwise, they are identical.

PS - Ultegra is more than adequate for cassettes. So is 105. I have one each of D/A, Ult, and 105, and notice no difference in shifting.

How about 12- 26? I got a SRAM cassette for my Shimano 105 equiped Cross bike and it seems to work fine. (Low gear = 38x26). David K

Dont be a weed! Get an 11-21 and put a 54 on the front!!

I’m using a 12-27 on mine and I couldn’t be happier.

I find that having the 53/25 combo available (when I use my 12-27) comes in quite handy on rolling terrain when I don’t want to drop to the small chainring
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amen
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Absolutely! I’ve found that I really treat my drivetrain like a 12-25 8-speed on the 53 and a 13-27 8-speed on the 39. I don’t really get into the 53-27 very often but I’ll run it out to 53-25 before dropping into the 39.