billallbritten

an SRAM 11-34t on a Trek 7500FX. My riding is "fitness" road on flat to rolling hills in West Kentucky. Longer rides are around 30 miles. Total weekly mileage runs between 70-100 miles. I've managed to drop 30 lbs (231 to 201) since LaborDay, pretty happy about that and am shooting for 185.

I'm looking at the Sheldon-Brown custom cassettes made up as either 13-24t or 13-30t. Tending to favor the latter slightly as per this reasoning. I'm not using the inner chainring much at all, the crankset is a 48-36-26 combination. Only time I've been using it lately is to shift down from the smaller to middle cogs in the rear to the 26 in front, rather than upshift several in back. Does that make sense?

I do tend to, going up some longer, steeper hills or into the wind, go to the 36f - 26r or 30r on the cassette. I have no practical use for the 11t cog on the cassette, have sometimes used the 48x13 downhill while maintaining my ~ 80-90rpm cadence (don't have a computer, use 15sec timings and count to make a guesstimate) but never on the flats. I'd have to be able to get down more over the handlebars to lower wind resistance and this is a flat bar bike, to have a practical use of the 11, next cog is 13.

A 26f-24r would probably accomodate the highest winds I'm likely to ride in, a 26f-30r combo definitely would. Very high headwinds and some of the hills around here might be an arguement for the 26-30 combo, particularly when tired.

The middle range gearing wouldn't have the big jumps it does now and would favor smoother pedal technique, I think, with either cassette, particularly the 13-24 one.

Any thoughts? Would I need to change the chain length? I'm thinking that wouldn't be mechanically necessary as I'm not going outside the original range the chain was set up for.

Thanks in advance for any help.

Sincerely,

Bill

johnny99

A narrower range cassette makes a lot of sense if you do long rides with a group. The closer spacing allows you to fine tune your efficiency for the group speed. For shorter rides out by yourself, your benefits are much smaller.

bbattle

One good thing about having the triple is that you can use a closely spaced cassette and still have plenty of range.

You could get a stock Ultegra 12-23 cassette. On the long hills, just drop down to the granny ring up front.

As you progress, you'll be using higher gears and at higher cadences. With the 12-23, you've got the high and low gears you need now and room to grow as you transform into a lean, mean, cycling machine.

Then it'll be time to swap that triple for a compact double (50-34).

SpongeDad

Shimano makes 12-27 or a 12-25 cassettes that would probably work out fine for you. The 12-25 has a nicely spaced set of gears. You might use that small ring on some big climbs, but that shouldn't be a problem. I think as you get stronger, you may start to use a 48/12 combination even with a flat bar.

jschen

I think as long as you don't ever need your very lowest gears, it makes sense to get a tighter range of cogs and make better use of all three chainrings. As it is, you have pretty significant overlap between gears in your biggest and smallest chainring, and your middle chainring is fully redundant. If 26/25 is a sufficient low gear, I would second SpongeDad's suggestion of getting a 12-25 cassette.

billallbritten

Many thanks, I'll be changing it out in a couple of months, I should be pushing 1500 mi+ on the cassette and chain on the bike then and won't be tossing too much usability of the stock components - that 12-27 sounds good. My only trepidation was that I'm not a frequent user of the 13 that's on the bike now and that a 12 would be outside my ability. Good point, though, to think towards the future.

Sincerely,

Bill