Worth it to change cassette?

Hey all, I have my A race coming up in a couple of weeks, the beautiful GMSR.

Getting excited, and was feeling pretty fit till I reconed the course last weekend. I quickly realized that my gearing was sub-optimal. I’m on a 2019 Specialized Allez Comp with stock everything. It’s setup with a 52/36 up front, and 11/28 rear gearing. There’s one section with a 12% avg grade over 2 miles, with the last mile kicking up to 18% at points. I was about to fall over in the lowest gear.

I think a large part of this is my own fault since I’ve done the vast majority of my training inside in ERG mode, and generally keep cadence high. I’m just not used to those low-cadence stomps, especially for that long.

Do you all think that it would make an appreciable difference to spend the considerable $$ to switch out the chain/cassette to 11/32? I know I’m not going to get fitter, but by difference, I mean just the ability to stay at threshold till I want to surge, instead of being forced into a major surge.

As a positive, I got a great strava result on the climb by accident :slight_smile:

Assuming your derailleur can accept the bigger cassette then change if it benefits your riding style.

Yes - you should run something smaller than a 36 front and 28 rear. If you can afford it I’d switch to a compact for the road race, with a 30 in the back if you’re particularly concerned

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I can say from experience I was using 34-32 on a rental bike I had last summer in a granfondo, it was pretty great that I was able to maintain a nice power/cadence for the most part, but even in the >10% extended climbs I was grinding it out just to maintain 200w, like 50-60rpm, I might have been able to spin faster for more power but I was at altitude and that was affecting me. So I’d say it might be worth switching things up for GMSR, might be worth the reduced suffering of grinding out those miles.

A 36 in the front indicates the OP does have a compact - the minimum chainring size on a “traditional” crankset is 38T, with Shimano not delivering anything below 39T. Assuming Shimano (which the OP did not specify), 36T is the sign of a 110mm BCD crankset.

I’m fairly certain that a compact is 50/34 and a mid-compact is a 52/36. If he can afford to get the chain rings on his bike, switching from a mid-compact to a compact would get him a 34 in the front


can confirm, it’s marketed as a mid-compact. It’s not shimano though, its a praxis. I’ll price out the change, but per wiggle’s buying guide I should be fine up to a 32 in the rear, so that might be the cost-effective way to go for now, even with a new chain.

I would! Not enough time to fix the problem with training so why not fix it with technology?

With a mid-compact crank and a new chain it shouldn’t be a problem. Even with the same chain the 36-32 gearing would work but if you cross chain the big ring your day will probably be over. :wink:

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haha yep. Don’t want that end.

A “mid-compact”, a.k.a. a “semi-compact”, is a 110mm BCD crankset with a 52 or 53 large chainring. You can change that large chainring for a 50, and you have a choice between 32, 34 or 36T for the small chainring - neither of which will work on a 130mm BCD crank. Shimano standardized their cranks to 110mm BCD around 2014, making all their road cranksets “compact-compatible”; there is no compact vs non-compact crankset anymore, “compactitude” now only depends on the chainrings installed.

This said, going back to the OP, if you follow Shimano guidelines you must change the large chainring to 50T in order to go below 36T on the small, otherwise the bike will catch fire; there are large numbers of cyclists who have braved these recommendations and have lived to describe their experience. In other words: the OP could install a 34T on his setup.

Since you have a 36 up front, I assume it’s the 110mm BCD variant (they have both 110 and 130). They have a 34T chainring available (it’s on their 50/34 config). I’ll bet that any non-funky 110mm 5-hole chainring will fit in there as well (FSA, etc).

The chainring may well turn out to be less expensive than a cassette.

Why do you include the chain as part of the changes required? Is that to make it longer to cope with the larger cassette?

(Rule #1 of the chain installer: Never throw away the links removed to fit a chain.)
(Corrolary #1 of Rule #1: The more chains you install, the more unidentified chain bits you will accumulate.)

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I have this same bike and lived in a pretty hilly/mountainous area and bought an 11-32 to deal with it. It fit as just a simple swap and a slight B-limit adjustment. I had no trouble running it in the 52-32 (not on purpose but sometimes you’re just shifting and don’t realize till you hit the limit). I’m pretty sure the long cage derailleur can fit up to a 36 so it has enough arm to take up all the slack of a slightly longer chain. So depending on how they fitted the chain in the shop you might only be out the price of the cassette.

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I would just change the small chain ring only and just be very cautious when changing from big to small rings.


36 - 32 if you have a long enough derailer to cope with the 32. I changed my 11-28 to a 11-32 with a mid compact 52-36 and that go me up Hardknotts pass 80 - 90 miles in with a max grade around 28%

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I’ll probably just buy a cassette/chain online and take it into the shop to change it out. The 105 cassette is only $38 with free shipping at a couple of places now, so that seems like the easiest most cost-effective way to go.

Shimano recommends running a mid cage derailleur to run a 32 cassette, but I’ve done it on a short cage on all my wheelsets and bikes. Maybe it’s just not an ideal setup, but it does work with a short cage.

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I rock a 32 cassette on all of my bikes regardless. Minimal weight penalty and you won’t run into terrain you cant tackle. I think this will come stock on bikes down the road.