I have a standard Ultegra 6700 54/39 double on my road bike but i'm looking at changing to the 6750 50/34 Compact as I'm getting fed up of being the last one up hills on club rides and searching for gears that aren't there.
Although I can climb on the double it would be nice to spin up a big hill rather than chomp.
If I fit a compact will I need to change the front mech too? I don't think i'll need to but it's always nice to be sure before I make the purchase?
The frame is a Carbon Tarmac if that makes any difference.
Bike Forum
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A question about Compact Chainsets
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Posted 1 year ago #
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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.Posted 1 year ago # -
Shimano don't make a compact front mech, you just use a normal one but move it down slightly.
Posted 1 year ago # -
As I thought.
Cheers fellas.
Posted 1 year ago # -
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.
Posted 1 year ago # -
What cassette have you got?
I'm running an 11-25. Thing is I'm very rarely on the 54 ring which to me seem a waste and I live in a hilly area so a compact will be more benificial to me.Posted 1 year ago # -
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.
Posted 1 year ago # -
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
Posted 1 year ago # -
Sorry, meant 53 not 54.
Posted 1 year ago # -
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)
Posted 1 year ago # -
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.
Posted 1 year ago # -
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?Posted 1 year ago # -
38/27=1.407
38/25=1.52
38/23=1.6534/27=1.26
34/25=1.36
34/23=1.48So, changeing the cassette gives him a change of 1.52->1.41.
Changeing the chainset 1.52->1.36The 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.
Posted 1 year ago # -
Ultegra 11-28 cassette would give a bit more range.
Posted 1 year ago # -
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.
Posted 1 year ago # -
18 posts in and still not the compulsory MTFU post? something is wrong.
I think you need to MTFU
Posted 1 year ago # -
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.
Posted 1 year ago # -
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.
Posted 1 year ago # -
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.
Posted 1 year ago # -
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.
Posted 1 year ago # -
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.Posted 1 year ago # -
Thanks for making me sound like an egotistical tosser there njee
Posted 1 year ago # -
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.Posted 1 year ago # -
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 to myself for making me sound like an egotistical tosser therenjee
FTFY
Posted 1 year ago # -
Waaaaaaaaaaaaaaa!
Posted 1 year ago # -
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?
Posted 1 year ago # -
No, wrong, 10.7%
Stick to the Munros mate
Posted 1 year ago # -
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
Posted 1 year ago # -
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.
Posted 1 year ago # -
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.
Posted 1 year ago #
Topic Closed
This topic has been closed to new replies.
