11-23 or 11-25 cassette for largely flat race (10S)

The course of my next race is pretty much flat, and I’ve realised my 11-28 would leave me with too many easy gears.
I’ve never ridden anything as small as an 11-23 so I’m a bit nervous about going down that route. Are the smaller steps of the 23 worth it, or should I stick to a 25?


What gearing do you have in the front?

Good point! I have compact 50-34.

Go the 23, I’m currently running 39/53 with an 11-23, same goes on my indoor bike. I’d only go compact on my cyclocross or if the course had monster climbs. Plus your legs will love you for it.:stuck_out_tongue_winking_eye:

Having small steps between gears is preferable in my opinion but you still need to make sure the range is sufficient for your event. Use a gear calculator to work out your speed and cadence and your given gears and see if that suits your course and ability.

Thanks! I’ve been looking at the Sheldon Brown gear calculator, in the hope of working it out! I’m pretty sure I can live with a 23. I’m definitely more of a spinner than a grinder, but at 17.2kph at 90rpm for 34 front 23 back, I think I should be ok.

How flat??

According to the data I have from IM Maryland (which is pretty much as flat as it gets!) I spent 85% of the race either in the 55x 14, 15 and 16 and the sum total of just over 2 minutes in any of the 11 and 12, and the 25, 23 and 21.

If I were looking to change cassettes for a flat race like that again I’d try to make a franken block, a straight through 12-23. Obviously it depends on your strengths and exactly how flat the race is but especially as your on compact gearing at the front, I’m with @cpooleNZ that an 11-23 should work fine.

Thanks @JulianM for the info - that’s really helpful.
I think it will have some longish but very gradual climbs, certainly ones that will be ridden in aero all the time.