Originally Posted by Randybb

I have an old steel bike with a 7 speed 12-21 cassette and 53/42 chainings. I want to build a new 7 speed cassette with some lower gear ratios for climbing. I plan on doing some long distance touring in addition to fun short sprints through the park, or group rides.

Right now, I'm thinking about doing 12-15-17-19-21-23-26.

The 15-26 gives me a really good range on both chainrings, I can hit 32-33mph on the 53/15, and the 26t should give me the lower gear ratio I need for steep climbs. Looking at a speed/cadence table I can accelerate through the gears smoothly going from 90-100rpm, which is great.

The 12t would be reserved for fast descents where I'm hitting 40+mph.

What do you think? Makes sense?