what cassette size is best?

[trainertroy]

I am a triathlete who races is a variety of conditions, but the majority of racing and training rides here in Nor Cal seem to be hilly. I want to utilize a cassette size that will get me up the hills without compromising my flat road speed. My new bike came with an 11-23, but it is a bear on the hills! I just did the Donner Lake Tri and any of you familiar with it know that the climb is a bear anytime let alone with an 11-23... Any thoughts?

 

[BugMan]

The 23 i'm sure is a ***** for climbing in the Sierra Nevada, but I bet the 11 is really sweet on those descents!!
I debated about going to a 25 and decided I'd rather train to handle a 23 rather than make things easier. It just depends on how much climbing you do - in some terrains a 25 is the only way to make it through.
It's not mountainous where I live but it for sure is downright hilly - lots of steep grades but rarely longer than a 0.5-1.0 miles in length. A 12-23 works great for me, with your longer climbs you may really need a 25. If you go to a 25 definitely give up the 11 to keep the rest of your cogset intact. If you try to keep the 11 most of your cogs will be separated by 2-tooth steps - the fine gear tuning that 1-tooth steps give you will probably do better for your overall speed than keeping the 11 for your descents.
Now if you can crank out that 11 on the flats don't give it up!

 

[jrbldr]

I have a 12-27 on my Bianchi Alloro and it works well here on the Bay Area hills with a 53/39 CR. The spacing is 12-13-14-15-17-19-21-24-27. The 3-cog difference on the lower gears seems ok and it is still a single cog jump in the higher gears where you need them close.

 

[trainertroy]

Thanks BugMan, great advice!

Originally posted by BugMan
The 23 i'm sure is a ***** for climbing in the Sierra Nevada, but I bet the 11 is really sweet on those descents!!
I debated about going to a 25 and decided I'd rather train to handle a 23 rather than make things easier. It just depends on how much climbing you do - in some terrains a 25 is the only way to make it through.
It's not mountainous where I live but it for sure is downright hilly - lots of steep grades but rarely longer than a 0.5-1.0 miles in length. A 12-23 works great for me, with your longer climbs you may really need a 25. If you go to a 25 definitely give up the 11 to keep the rest of your cogset intact. If you try to keep the 11 most of your cogs will be separated by 2-tooth steps - the fine gear tuning that 1-tooth steps give you will probably do better for your overall speed than keeping the 11 for your descents.
Now if you can crank out that 11 on the flats don't give it up!