compact to semicompact

Discuss light weight issues concerning road bikes & parts.
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civdic
Posts: 155
Joined: Thu Feb 10, 2011 8:58 pm

by civdic

I tried searching but couldn't find anything. I'm going from compact to semicompact praxis rings. How many chain links do I add or will the chain length be OK?

system787
Posts: 138
Joined: Fri Mar 16, 2012 1:49 pm
Location: LA/OC, California

by system787

Generally, you should be able to swap between compact and standard with no problems. However, if your chain in big/small is giving your derailleur problems (meaning your chain is barely long enough for compact), then swapping cranks will require more links.

If you measured your chain using the traditional method, or big/big + 2 links, then you should be fine.

gilesharrison
Posts: 231
Joined: Tue Nov 04, 2008 6:44 pm

by gilesharrison

Erm, am I being thick? What's 'semi-compact'? Never heard of that. What's the BCD?

ricerocket
Posts: 502
Joined: Mon Sep 27, 2010 8:38 am

by ricerocket

52/36 I believe. It's the new rage.

110bcd (duh).

topflightpro
Posts: 815
Joined: Tue Jan 13, 2009 2:35 am

by topflightpro

ricerocket wrote:52/36 I believe. It's the new rage.

110bcd (duh).


It's something Specialized started promoting last year and are still promoting now. They don't offer straight up compacts on their Tarmacs anymore.

It kind of makes sense - 50/34 is really small gearing. I know I replaced the 34 ring on my wife's crankset with a 36.

And I've been running a 52/39 on my crit bike for awhile now. I cannot tell a difference between it and the 53/39 on my other bike.

civdic
Posts: 155
Joined: Thu Feb 10, 2011 8:58 pm

by civdic

[quote= It's something Specialized started promoting last year and are still promoting now. They don't offer straight up compacts on their Tarmacs anymore.

It kind of makes sense - 50/34 is really small gearing. I know I replaced the 34 ring on my wife's crankset with a 36.

And I've been running a 52/39 on my crit bike for awhile now. I cannot tell a difference between it and the 53/39 on my other bike.[/quote]


I found the compact just a bit to small. I'm hoping the semicompact does the trick.

415brian
Posts: 52
Joined: Fri Sep 30, 2011 4:48 pm

by 415brian

here's a chain length calculator. you can plug-in old vs. new and see if there's a delta:

http://www.epicidiot.com/sports/chain_length_calculator.htm

notsoswift
Posts: 176
Joined: Mon Mar 07, 2011 10:00 am
Location: Melbourne

by notsoswift

I think for most of us Semi is perfect, 36x25 is a great gear for some many bigger hills and if you are really desperate a 36x27 will get you up almost anything. My Look has compacts and I never use 34x25 and it is too easy to wind out the 50x11 in the big sprints, 52x11 would be great
Unfortunately Campy announced they were doing it a month after I bought my 53/39 and I didn't want 50/34 on the Cyfac... since semi mounts on a compact PCD I am pretty stuffed unless I throw away a brand new Chorus crank

Valbrona
Posts: 1486
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

topflightpro wrote:
ricerocket wrote:52/36 I believe. It's the new rage.

110bcd (duh).


It's something Specialized started promoting last year and are still promoting now.[quote]

Who at Specialized came up with that one?

tmanley
Posts: 238
Joined: Tue Jul 25, 2006 5:53 pm
Location: San Jose, CA
Contact:

by tmanley

I've been running a 52/36 combination of Rotor q-rings for the past 4 years. Across the spectrum of hilly training rides/races and crits this gearing has given me everything i need when I use my 11-25 cassette (RR's) or 11-21 (crits). Now that it's the off-season it's time to treat myself to some easy climbing w/ my 13-29!

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