[Closed] A question about Compact Chainsets

A standard double mech will work fine. I think specific compact ones work slightly smoother but i doubt you'd notice.
I've had 2 bikes with compact chainsets (50/34 and 50/36) both with standard double mechs and i never had an issue.

Shimano don't make a compact front mech, you just use a normal one but move it down slightly.

As I thought.
Cheers fellas. 😀

What cassette have you got? It maybe a case of just getting a different cassette which has to be the cheapest option. Having said that, I'm a big fan of chainsets with a 110bcd as I like having lots of options.

What cassette have you got?

54's an odd ring size but I'd still just try a 12-27 cassette first (cheaper) and maybe change down to a 52 big ring when the current one wears out.

I've an 11-26 and I find on the 34-50 I very rarely use the bottom half of the cassette. No immense hills for me though, just commuting

Sorry, meant 53 not 54. 😳

If it helps, I run a compact through winter,(& for very hilly sportives) and change back and forth, as I see fit. Just move the mech up and down, and have a dedicated chain for each. (length)

a 12-27 will make **** all difference - equivalent one gear at most?

Going to 34 will give an equivalent 1-2 gears, you can then look at cassettes...but you may need a new chain too.

Chain is still okay but I will change it and keep it for the double like Pooley suggests.
I assume I won't need to change the BB?

Check out Sheldon Brown's gear calculator.

You can plug in your current spec and see what difference a compact makes. You can then work out if you need a new block to give you a good spread of gears that will allow you to use both of your chainrings.

[url= http://www.sheldonbrown.com/gears/ ]GEAR CALC[/url]

38/27=1.407
38/25=1.52
38/23=1.65

34/27=1.26
34/25=1.36
34/23=1.48

So, changeing the cassette gives him a change of 1.52->1.41.
Changeing the chainset 1.52->1.36

The difference is marginal with a 25t cassette. I went for a compact and 11-23 as I wanted the spinny gears of the compact but still wanted the small spaces between gears, it still leaves you with an overlap of ~5 gears (34-11 is the same as 50-16) which I feel is more than enough, just shift the front when your 3 gears from the end of the cassette.

Ultegra 11-28 cassette would give a bit more range.

I used to run a 52/42 with a 13-26.

I moved to a hilly area and wanted to enter a few local sportives so I changed to a stronglight compact 48/34. It seems like a huge change, but I only lost one gear from the top end and gained three at the bottom.

I also don't get as much overlap.

18 posts in and still not the compulsory MTFU post? something is wrong.

I think you need to MTFU 😉

I agree with Warton. I've climbed vertical walls with a 68t front ring and a 4t rear cog. MTFU fella!

Tshk, kids today don't know they're born 🙄

Oh, and yes, if you go for a Shimano compact chainset you should be able to slot in straight into the current bb. Unless crit racing/sprinting you'll not miss the larger front ring.

I've done audaxes that go straight up 1 in 4 climbs on 39x25, it is perfectly possible, but it is nicer to have the option of sitting and spinning.

I've done audaxes that go straight up 1 in 4 climbs on 39x25, it is perfectly possible for me, with my level of fitness, but you may not be as fit and it is nicer to have the option of sitting and spinning.

That's better.

I'd always used standard doubles, but my commuter/winter bike has a compact and I'd be tempted to try it on the race bike next time.

I didn't need to alter chain length going triple to compact (on 105, but I bought an ISIS compact as Shimano didn't do them then). Don't think I moved the mech either.. it's pretty agricultural the front shifting but it works just fine and has done for about 5 years now, even with the triple front shifter.

I think compacts are great, so I'm not arguing against them. But chaining your chainset is an expensive option. Yes, a change in cassette will give you an bit more and if you are never using the 53, then you can always go down to a 46 on a 130bcd chainset and even a 38inner.
But if you don't mind spending on a chainset then get a new one and it'll fit right in. I run compact but a 36 inner ring.

Thanks for making me sound like an egotistical tosser there njee 😐

I have just ordered a one along with a new chain. Will be here tomorrow morning. Yay! 😀
Weather looks rubbish this weekend so I will be stripping the bike down for a good service.

TINAS he's on 39 so going to 34 gives a 13% lower gear whereas a 27T cassette gives an 8% lower gear. 62.5% more of a difference.

EDIT: Too late!

anotherdeadhero - Member
Thanks [u]to myself[/u] for making me sound like an egotistical tosser there [s]njee[/s]

FTFY 😡

Waaaaaaaaaaaaaaa!

cynic-al - Member
TINAS he's on 39 so going to 34 gives a 13% lower gear whereas a 27T cassette gives an 8% lower gear. 62.5% more of a difference.

Going to a 28T cassette would be 12% lower - is that right?

No, wrong, 10.7%

Stick to the Munros mate 😉

Stupidly when I ordered my Ribble winter bike (and knowing nothing about road bikes), I left it with the default 54/39 and 11-23.

It's now compact and 12-27 🙂 Tiagra chainset was < £30 in the Ribble sale and I bought a nearly new Ultegra cassette off here. I am a far happier man! Certainly I wasn't troubling the big ring much before.

It's hilly here in the Malverns. And I'm carrying a laptop on my commute. And I'm weak. Clearly 😉

I switched out my rear cassette on a standard double to one with a 28 rather than a 24 sprocket for a trip to the Lakes last year. A cheap option, and I'm pretty sure it made the difference between making it up Honnister in one and not.

Since then I've bought a new bike with a compact, and it definitely seems like a better option for me, but it's an expensive switch compared to swapping a cassette.

Yay! I love bike part deliveries! 😀
Ordered yesterday at 3pm from Parkers International and arrived at 9.30 this morning. Top work from PI and RM.
Was expecting it be be OEM as it was only £143 which is way cheaper than anywhere else.
Can't wait til Sunday to try it out. 😀
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