General Discussion Triathlon Talk » Help with compact cranks.... Rss Feed  
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2008-02-21 5:01 PM

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Subject: Help with compact cranks....
So, I've decided I would like to switch to a compact crank. Now the question is -- what to get? There are several on sale at Performance right now. Prices are pretty close, so I'm wondering if anyone has suggestions for what criteria I should consider in my decision? Am I likely to have compatability issues with any of these? (My bike has shimano components, ultegra/dura-ace mix)

Here are the sets on sale at performance, any of these stand out as a better deal? (All are 50/34 except the Campagnolo Centaur, which is 48/34)

Shimano FC-R700: http://www.performancebike.com/shop/profile.cfm?SKU=22337&subcatego...

Campagnolo Centaur: http://www.performancebike.com/shop/profile.cfm?SKU=24554&subcatego...

Ritchey WCS 110 V: http://www.performancebike.com/shop/profile.cfm?SKU=20106&subcatego...

FSA Gossamer: http://www.performancebike.com/shop/profile.cfm?SKU=21957&subcatego...

E3 Halo: http://www.performancebike.com/shop/profile.cfm?SKU=24364&subcatego...

Thanks for the help!!




2008-02-21 5:09 PM
in reply to: #1226883

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Veteran
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Subject: RE: Help with compact cranks....
I just got the fsa gossamer for 124.00 from speedgoat.com and free shipping. Chose fsa cause I had fsa on my bike and didn't have to change bottom brackets plus I have been happy with the performance of their stuff.
John.
2008-02-21 5:43 PM
in reply to: #1226883

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Subject: RE: Help with compact cranks....
Campy doesnt play well with Shimano. Unless you're replacing everything including shifters, scratch that one off.

FSA is always a solid choice.
2008-02-21 6:20 PM
in reply to: #1226883

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Subject: RE: Help with compact cranks....

I have the FSA on my Orbea and the Shimano on my tri bike Kuota K factor.

I don't feel a difference...does color matter? Both match other components better on each bike.

You'll love a compact..not at Bassman but for sure if you end up doing IMLP in '09. 

Be sure you get the right crank arm length for you. 

2008-02-21 6:23 PM
in reply to: #1226883

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Master
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Subject: RE: Help with compact cranks....
I have FSA compacts.  Love them!
2008-02-21 6:45 PM
in reply to: #1227044

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Subject: RE: Help with compact cranks....
KathyG - 2008-02-21 6:20 PM

Be sure you get the right crank arm length for you. 



Okay.... so how do I know what's the correct crank arm length for me?




p.s. I've read some reviews indicating some folks have trouble with FSA compacts, but I have yet to see a negative review of the Shimano... My bike DOES have a FSA crank (non-compact) now, and I've had no trouble with it.


2008-02-21 8:21 PM
in reply to: #1227084

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Subject: RE: Help with compact cranks....
jsnowash - 2008-02-21 7:45 PM
KathyG - 2008-02-21 6:20 PM

Be sure you get the right crank arm length for you.

Okay.... so how do I know what's the correct crank arm length for me? p.s. I've read some reviews indicating some folks have trouble with FSA compacts, but I have yet to see a negative review of the Shimano... My bike DOES have a FSA crank (non-compact) now, and I've had no trouble with it.

It is based mostly on how tall you are. Also you could measure what size you have now.

If I recall right you are a few inches taller than I am. I'd look at the bike specs of the bike you currently have in your size for a guide.

I'm pretty sure mine are 170 but I'm 5'5.5" 

2008-02-22 8:34 AM
in reply to: #1226883

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Subject: RE: Help with compact cranks....
I have an FSA gossamer. Came with bike--50/34 (think) It sucks. Have had BB noise issues, its not real stiff. Rest of drive train is Campy. FSA and Campagnolo not truly compatible, so have also had FD shifting issues. Upgrading to Campy Chorus Ultra Torque.

Still, I think FSA is good stuff, just not on my particular bike.
2008-02-22 9:37 AM
in reply to: #1227084

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Subject: RE: Help with compact cranks....
jsnowash - 2008-02-21 7:45 PM

KathyG - 2008-02-21 6:20 PM

Be sure you get the right crank arm length for you. 



Okay.... so how do I know what's the correct crank arm length for me?


Taken from this study - > http://www.ncbi.nlm.nih.gov/pubmed/11417428?dopt=Abstract

"The optimal crank length was 20% of leg length or 41% of tibia length. These data suggest that pedal speed (which constrains muscle shortening velocity) and pedaling rate (which affects muscle excitation state) exert distinct effects that influence muscular power during cycling. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults."

As always, sheldon brown has a pretty good read on this as well -> http://www.sheldonbrown.com/cranks.html

2008-02-22 9:42 AM
in reply to: #1226883

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Subject: RE: Help with compact cranks....
I have the Shimano r700 on my tri bike and really like it. You will need a new tool to install the botttom bracket.
2008-02-22 10:01 AM
in reply to: #1226883

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Master
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Subject: RE: Help with compact cranks....

FYI,  if you see a crank with a 48 big ring (like the Centaur 48/34) it is a Cylocross crank, not a regular compact crank for roadies.    Not that it wouldn't work, you just might run out of gear occastionally.  

FOr crank lenght, check the original specs to see what it came with.  It should also be stamped somewhere on the crank arm, usually someplace you can't see easily unless you go looking for it.   Generally it is 170 or 175, but if you are short it might be 165.   Match the crank arm length when you buy a new crank, or you could have fit/geometry issues. 

The only other thing to look for is the Bottom Bracket.  You'll probably need a new BB to match the new crank.  Anymore, the BB is designed for a specific crank, so read the specs for the crank to see which one you need.  You may also need a special tool or two to install the crank.  (BB tool and/or crank puller)

One other thing the might be considered is the rear cassette.  If you are changing your gearing to compact, you may want to get a wider range in the rear.  Maybe go with an 11t small cog to get more speed out of the new 50t, or a 27t big cog to help even more with climbs.  Not required, it would just be a good time to do it.    It is probably a good time for a new chain as well. 

This looked like a good deal on a nice crank:

http://www.pricepoint.com/detail/15927-100_TRUEL7-3-Parts-56-Cranks/Bolts/Truvativ-Elita-2.2-Road-Crankset-'07.htm



2008-02-22 10:04 AM
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Subject: RE: Help with compact cranks....
Don't forget that a standard front deraileur has a maxiumum tooth difference = 14. This means; it works just fine on a 53/39 b/c that is 14 teeth differnce of the rings. A 50/34 compact is a 16 tooth difference. IMHO: Buy the FSA compact front derailleur as well (IRD also makes one).
2008-02-22 11:34 AM
in reply to: #1227936

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Subject: RE: Help with compact cranks....

ChicagoMan65 - 2008-02-22 8:34 AM I have an FSA gossamer. Came with bike--50/34 (think) It sucks. Have had BB noise issues, its not real stiff. Rest of drive train is Campy. FSA and Campagnolo not truly compatible, so have also had FD shifting issues. Upgrading to Campy Chorus Ultra Torque.

Still, I think FSA is good stuff, just not on my particular bike.

FWIW, my bike came with Campy and an FSA Gossamer (53/39).  The ISIS bottom bracket got wrecked pretty quick.  But a new bb worked fine and after switching to an FSA mega-exo compact, I have had zero problems.  Didn't even need to change the FD.  No compatability issues for me.

2008-02-22 12:53 PM
in reply to: #1226883

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Lethbridge, Alberta
Subject: RE: Help with compact cranks....
Have you considered this compact crankset.
2008-02-22 1:13 PM
in reply to: #1226883

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Subject: RE: Help with compact cranks....
sheesh... that's almost 2x what the BIKE cost!
2008-02-22 1:18 PM
in reply to: #1228931

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Subject: RE: Help with compact cranks....
jsnowash - 2008-02-22 1:13 PM sheesh... that's almost 2x what the BIKE cost!
That's almost half what my car cost.


2008-02-22 2:35 PM
in reply to: #1226883

Subject: ...
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2008-02-22 2:46 PM
in reply to: #1229248

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Subject: RE: Help with compact cranks....

AcesFull - 2008-02-22 1:35 PM Hijack: I've been wondering the same thing.  I have a Felt S32, with 105/Ultegra mix.  I live in a pretty hilly area, and feel like I could really benefit from compact cranks.  Also looked at Performance and was lost as to what to buy.  I'm 5'8" and am riding a 54cm bike.  Any advice would be appreciated. 

Check out the one from pricepoint I linked above.  It inlcudes a new BB as well.   Should be a pretty nice setup and about the same component level as what came on the s32.   I think you'll prob want a 172.5 on the crank length, but get the same length as what came on the bike. 

2008-02-22 3:09 PM
in reply to: #1229248

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Subject: RE: Help with compact cranks....

AcesFull - 2008-02-22 2:35 PM Hijack: I've been wondering the same thing.  I have a Felt S32, with 105/Ultegra mix.  I live in a pretty hilly area, and feel like I could really benefit from compact cranks.  Also looked at Performance and was lost as to what to buy.  I'm 5'8" and am riding a 54cm bike.  Any advice would be appreciated. 
From what I have read the compact cranks aren't necessarily for hilly areas but can be.  Use this to calculate different gear ratios using standard and compact cranks and I am certain you can find a pretty comparable gearing ration using standard cranks as you would with compact. 

For arguement sake if you currently have a 53-39 with a 12-25 cassette and go to a 50-34 with a 11-23 cassette you top speeds at 90rpms will be:

53-12  31.1
39-25  11.0

 50-11 32
34-23 10.4

As you can see you really don't gain much is ease by going to the compact.  I think there are really others reason for going to compacts but I have no idea what they are.



Edited by kproudfoot 2008-02-22 3:17 PM
2008-02-22 3:50 PM
in reply to: #1229306

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Subject: RE: Help with compact cranks....
tkbslc - 2008-02-22 2:46 PM

AcesFull - 2008-02-22 1:35 PM Hijack: I've been wondering the same thing.  I have a Felt S32, with 105/Ultegra mix.  I live in a pretty hilly area, and feel like I could really benefit from compact cranks.  Also looked at Performance and was lost as to what to buy.  I'm 5'8" and am riding a 54cm bike.  Any advice would be appreciated. 

Check out the one from pricepoint I linked above.  It inlcudes a new BB as well.   Should be a pretty nice setup and about the same component level as what came on the s32.   I think you'll prob want a 172.5 on the crank length, but get the same length as what came on the bike. 



So, I notice that this crank is a 36/50, vs 34/50 I've seen for most others. Any benefit or detriment to the two extra teeth?

And another question for you compact users out there...

Have you needed to do much tinkering with your FD when you changed to the compact? One of the claims of the Shimano crank is that it supposedly works with standard FD's and requires no adjustment. And how much of a hassle is it to adjust the FD if needed? (I would likely be having all of this done at a LBS, anyway...)

2008-02-22 4:50 PM
in reply to: #1229407

Lethbridge, Alberta
Subject: RE: Help with compact cranks....
kproudfoot - 2008-02-22 2:09 PM
...

For arguement sake if you currently have a 53-39 with a 12-25 cassette and go to a 50-34 with a 11-23 cassette you top speeds at 90rpms will be:

53-12 31.1
39-25 11.0

50-11 32
34-23 10.4

As you can see you really don't gain much is ease by going to the compact. I think there are really others reason for going to compacts but I have no idea what they are.


Instead of changing the cassette, if you leave the 12-25 behind compact cranks, you get:
50-12 29.3
34-25 9.6

If someone is worried about hills, then they probably will not spend a lot of time in a 50-11 anyway but the 34-25 combination may see a lot of use. In that case the trade could really help.


2008-02-22 4:53 PM
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Subject: RE: Help with compact cranks....
Micawber - 2008-02-22 4:50 PM
kproudfoot - 2008-02-22 2:09 PM ...

For arguement sake if you currently have a 53-39 with a 12-25 cassette and go to a 50-34 with a 11-23 cassette you top speeds at 90rpms will be:

53-12 31.1
39-25 11.0

50-11 32
34-23 10.4

As you can see you really don't gain much is ease by going to the compact. I think there are really others reason for going to compacts but I have no idea what they are.

Instead of changing the cassette, if you leave the 12-25 behind compact cranks, you get: 50-12 29.3 34-25 9.6 If someone is worried about hills, then they probably will not spend a lot of time in a 50-11 anyway but the 34-25 combination may see a lot of use. In that case the trade could really help.
Definately doable but I thought most people who moved to CC changed rear gears to a small gear say 11 to keep the high end speed.  You idea definately works but I don't think this is the norm but could be wrong.
2008-02-22 5:18 PM
in reply to: #1226883

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Subject: RE: Help with compact cranks....
I am trying the compact to keep my chainline straighter. With the smaller big ring and I keep the 12-25 I am riding in the 4th and 5th gear most of the time instead of the 2nd or 3rd from the top on the cassette. So far it seems to be working but anything over 33 mph you are out of gear but who really pedals at that speed plus? Most people I ride with are enjoying the free speed.
Climbing RPM is higher as well. I think I will stick with it.
John.
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