Originally Posted by
rivers
I'm currently running a 50/34 with an 11-28 (105) on one of my bikes. On long, gradual descents I find that I'm starting to spin out, so I'm toying with the idea of swapping over to a 52/36. If I swap to a semi-compact, should I also swap the cassette to an 11-30 to keep the lowest gear relatively similar? The area where I live is hilly, not mountainous, however. Mostly rolling, with several 3 and 4 category climbs dotted around, but I don't think anything much bigger than that. Advantages and/or disadvantages to making the swap? If I swap, should I keep the 11-28 on the back and see how I get on?
Yes
And forget that nonsense about whether you are
actually spinning out or not. If you have to spin - at all - to accelerate to 35mph+ on a negative grade, you need a bigger chain ring, and you're probably strong enough to manage your climbs with a mid, too. A bit of mashing at the top of a descent pays such nice dividends.
Why anyone thinks its OK for a geared bike to require one to spin on normal descents is beyond me. Maybe they just don't like to go fast.