General Discussion Triathlon Talk » Compact Cranks – The bottom line? Rss Feed  
Moderators: jmk-brooklyn, Ron Reply
2007-05-11 9:08 AM

Pro
3903
20001000500100100100100
Andover
Subject: Compact Cranks – The bottom line?
It isn’t often that I find myself asking for bike advice but, to be honest, I don’t know a lot about compacts. I’ve searched, and read through, several posts on the topic but haven’t seen the definitive list on what one needs to swap when upgrading from a standard double (I have an FSA on my P3SL).

So, in addition to the cranks themselves (I’m assuming, like most cranks nowadays, they come with rings), what does one need to swap? (I’ll also assume that as long as the spline on the cranks matches up with the BB, that you don’t need to swap the BB—spindle length shouldn’t change, right?)

Thanks for any guidance!

Rob

BTW:
Does anyone know if Shimano makes different level compacts (Ultegra, Dura-Ace)? I usually only see one listed when I check the usual mail-order sites.


2007-05-11 9:14 AM
in reply to: #796958

User image

Master
1557
10005002525
Maine
Subject: RE: Compact Cranks – The bottom line?

The only thing I had to do when I switched to a compact was to shorten my chain.

I don't know about different levels of shimano compacts - I can't imagine the difference between ultegra and dura ace in a crank would be much more than a slight weight difference.

2007-05-11 10:06 AM
in reply to: #796958

User image

Extreme Veteran
562
5002525
Subject: RE: Compact Cranks – The bottom line?

You can read a bunch of nattering about front derailleur height, even compact specific FDs.  Not necessary IMO.  I've put compacts back and forth on two bikes and gotten it to work well without any front derailleur changes or even chain length changes.

Since you can't adjust your front derailleur's height, just check to make sure you don't have a rubbing chain on the bottom of the derailleur's link when in the small ring.  You might have to toe it in or out slightly. 

2007-05-11 10:09 AM
in reply to: #796958

Elite
3130
2000100010025
Los Alamos, NM
Subject: RE: Compact Cranks – The bottom line?

I recently put a compact onto my 1996 litespeed ultegra - I changed the BB, moved the FD down and shortened the chain. The whole operation took about an hour. Specialized tools required were BB removal tool and crank puller. (edit: and chain tool of course)

 

 



Edited by ScottoNM 2007-05-11 10:10 AM
2007-05-11 10:18 AM
in reply to: #796958

User image

Champion
6786
50001000500100100252525
Two seat rocket plane
Subject: RE: Compact Cranks – The bottom line?

In moving from a regular double to a compact double, Assuming that the BB is the same type, all you are going to need to do is

pull old crank

Put on new crank

shorten chain a few links

adjust deraileur height (maybe tweak your limit screws a little)

that ought to do it

2007-05-11 11:44 AM
in reply to: #796958

User image

Champion
10536
5000500050025
Puyallup, Washington
Subject: RE: Compact Cranks – The bottom line?
You may not NEED to change anything else at all (except maybe taking out a few chain links).

If you go with a 50/34 instead of the 53/39, your range up front is only increased by 2 teeth there. Unless you're already running something like an 11-27 in back, you wouldn't need to go with a long cage derailleur -- check the total capacity of that rear unit. If you've got a braze-on front derailleur, you might need to get an FSA front to get low enough to the chainring. If it's a clamp-style, then all you'd need to do is lower it on the seat tube.


2007-05-11 11:59 AM
in reply to: #796958

User image

Champion
19814
50005000500020002000500100100100
MA
Subject: RE: Compact Cranks – The bottom line?

Only thing I can help with is Shimano only makes one level of compact cranks. They place it in between Ultegra and Dur-Ace. My two new bikes are Ultegra and I had to pay a small amount extra for the Shimano compact crank when I bought my Tarmac.

 

2007-05-11 12:07 PM
in reply to: #796958

User image

Elite
2608
2000500100
Denver, Colorado
Gold member
Subject: RE: Compact Cranks – The bottom line?
This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.
2007-05-11 12:15 PM
in reply to: #797215

User image

Master
1810
1000500100100100
Morse Lake, Noblesville, Indiana
Subject: RE: Compact Cranks – The bottom line?
KathyG - 2007-05-11 12:59 PM

Only thing I can help with is Shimano only makes one level of compact cranks. They place it in between Ultegra and Dur-Ace. My two new bikes are Ultegra and I had to pay a small amount extra for the Shimano compact crank when I bought my Tarmac.

 



Shimano actually makes 3 levels of compact cranks, the FC-R700, FC-R600 and the FC-R550. People are comparing the 700 to Dura Ace and the 600 to between Ultegra and Dura Ace. I am assuming the 550 is about 105 spec, but I don't really know for sure. 700 is about $250, 600 is about $150 and the 550 is about $89.
2007-05-11 12:16 PM
in reply to: #797232

User image

Master
1810
1000500100100100
Morse Lake, Noblesville, Indiana
Subject: RE: Compact Cranks – The bottom line?
MikeTheBear - 2007-05-11 1:07 PM

This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.


Compact gives you a simmilar range to a tripple with the weight of a double.
2007-05-11 12:29 PM
in reply to: #797264

User image

Extreme Veteran
434
10010010010025
Orangeville, Ontario
Subject: RE: Compact Cranks – The bottom line?
tjtryon - 2007-05-11 12:16 PM

MikeTheBear - 2007-05-11 1:07 PM

This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.


Compact gives you a simmilar range to a tripple with the weight of a double.


Don't you lose a lot of high end? Speed?

Geoff


2007-05-11 12:39 PM
in reply to: #797289

User image

Master
1810
1000500100100100
Morse Lake, Noblesville, Indiana
Subject: RE: Compact Cranks – The bottom line?
geoffs - 2007-05-11 1:29 PM

tjtryon - 2007-05-11 12:16 PM

MikeTheBear - 2007-05-11 1:07 PM

This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.


Compact gives you a simmilar range to a tripple with the weight of a double.


Don't you lose a lot of high end? Speed?

Geoff


Sure, if you can pedal flat out at insane fast speeds constantly, but then again, if you can do that, a compact crank is not what you want. I imagine that since you are asking that questions, that you are simmilar to alot of the rest of us on the list who would struggle to outspin a compact crank, except for downhills...
2007-05-11 1:06 PM
in reply to: #797298

User image

Extreme Veteran
434
10010010010025
Orangeville, Ontario
Subject: RE: Compact Cranks – The bottom line?
tjtryon - 2007-05-11 12:39 PM

geoffs - 2007-05-11 1:29 PM

tjtryon - 2007-05-11 12:16 PM

MikeTheBear - 2007-05-11 1:07 PM

This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.


Compact gives you a simmilar range to a tripple with the weight of a double.


Don't you lose a lot of high end? Speed?

Geoff


Sure, if you can pedal flat out at insane fast speeds constantly, but then again, if you can do that, a compact crank is not what you want. I imagine that since you are asking that questions, that you are simmilar to alot of the rest of us on the list who would struggle to outspin a compact crank, except for downhills...


No...I push a 55t, I was just curious if the it's just the small ring that's different or both. If it's just the small ring that's different then you wouldn't run out of gears on the flats.
2007-05-11 1:18 PM
in reply to: #796958

Pro
3903
20001000500100100100100
Andover
Subject: RE: Compact Cranks – The bottom line?
Thanks for the great info, peeps.

Enjoy the weekend!

Rob
2007-05-11 1:38 PM
in reply to: #797356

User image

Champion
6786
50001000500100100252525
Two seat rocket plane
Subject: RE: Compact Cranks – The bottom line?

geoffs - 2007-05-11 1:06 PM
tjtryon - 2007-05-11 12:39 PM
geoffs - 2007-05-11 1:29 PM
tjtryon - 2007-05-11 12:16 PM
MikeTheBear - 2007-05-11 1:07 PM This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.
Compact gives you a simmilar range to a tripple with the weight of a double.
Don't you lose a lot of high end? Speed? Geoff
Sure, if you can pedal flat out at insane fast speeds constantly, but then again, if you can do that, a compact crank is not what you want. I imagine that since you are asking that questions, that you are simmilar to alot of the rest of us on the list who would struggle to outspin a compact crank, except for downhills...
No...I push a 55t, I was just curious if the it's just the small ring that's different or both. If it's just the small ring that's different then you wouldn't run out of gears on the flats.

Typical chainrings on a compact are 50/34

a 50/11 is about the same gear as a 53/12 (actually a little higher). A 34/27 is about the same gear as a 30/25.  If you are concerned about having a low enough gear for climbing, a 12/27 cassette on a compact gives you almost the same low gear as a triple. If you are concerned about top end a 11/23 cassette will give you the same gear spread as a 53/39 with a 12-27.

A compact double will shift better and weigh less than a triple.

Are you rocking a 55 on 700c wheels?...that's some big meat.

2007-05-18 6:16 AM
in reply to: #796958

Pro
3903
20001000500100100100100
Andover
Subject: RE: Compact Cranks – The bottom line?
NOTE: When installing an FSA compact with MegaExo BB, use the dust-cap "protector tool" when pushing the drive-side crank through the BB.

Also, although the front derailleur did look a little high, the bike shifted fine so we figured, “if it ain’t broke, don’t try and fix it!”

Other than that, the installation went well.


2007-05-18 7:09 AM
in reply to: #796958

User image

Pro
4206
20002000100100
Los Angeles, CA
Subject: RE: Compact Cranks – The bottom line?
I needed to get a long cage front derailer to get mine to work right. I had a slow and sometimes non-existent shift, even bringing it in to get it adjusted by the LBS. I had an ultegra shimano one didn't work with the FSA gossomer compacts I got. The long cage derailer's brand was FSA and made specifically for compacts.
2007-05-18 7:17 AM
in reply to: #796958

Pro
3903
20001000500100100100100
Andover
Subject: RE: Compact Cranks – The bottom line?
We put the FSA on Arron's (burniect) bike last night and didn't even have to touch the derailleur (Shimano 105). Of course, he had an FSA w/ the same BB already on his bike so the adjustment/alignment was probably close enough. Hope I'm half as lucky when I install on the Cervelo – going from FSA ISIS to the MegaExo (Dura-Ace der).
2007-05-18 9:50 AM
in reply to: #797232

User image

Master
3019
20001000
West Jordan, UT
Subject: RE: Compact Cranks – The bottom line?

MikeTheBear - 2007-05-11 11:07 AM This is an extremely basic question, but what is the advantage of a compact crank? Is it better to use a compact for steeper rides? If so, why would a compact be better than a triple crankset for steep rides? Thanks.

Others have mentioned weight, you will save some, but maybe 100 grams tops.   Pick up a spare 30T ring sometime.  It is insanely light.    I think the biggest reason is that people prefer the shifting response on a double, but like the gear range of a triple.   The compact cranks puts you somewhere in the middle.   Plus, if you bike came with a double, but you need lower gears it is more $$ to go to a triple.   You would need a triple deraileur and a new triple left shifter along with the new crank.   With a compact you just need the new crankset.  

New Thread
General Discussion Triathlon Talk » Compact Cranks – The bottom line? Rss Feed