HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Blog NEW Articles FAQ Contact About




Post new topic Reply to topic  [ 7 posts ] 
Author Message
PostPosted: Mon Jan 30, 2012 11:07 pm 
Offline

Joined: Wed Sep 16, 2009 10:25 am
Posts: 173
Location: Australia
So I installed my new lovely new FC-M985 cranks on my Cannondale Flash F3 Alloy, and noticed the clearance between the driveside crankarm and the chainstay is quite tight (about 3mm), but not critical.

I just wanted to confirm the tight 3mm clearance is acceptable for this crank? And I wonder what is the best case scenario for this crank since the q-factor is 3mm less on each side than the M980- ie most frames would have this same issue?

The bottom bracket is 73mm so I have one 2.5mm spacer on the driveside cup. I gather I can't cheat and add another spacer since the non-drive side wouldn't have enough spindle?

Other than that, amazing crank, light and very well finished!

Many thanks


Top
 Profile  
 
Posted: Mon Jan 30, 2012 11:07 pm 


Top
  
 
PostPosted: Tue Jan 31, 2012 4:46 am 
Offline
Shop Owner

Joined: Sat Jun 13, 2009 4:02 am
Posts: 1976
Location: NoVA/DC
3mm is fine. cranks dont flex much in that direction when in the rearmost position.


Top
 Profile  
 
PostPosted: Tue Jan 31, 2012 5:03 am 
Offline

Joined: Wed Sep 16, 2009 10:25 am
Posts: 173
Location: Australia
Many thanks for the reply thisisatest, pretty much what I was thinking/hoping.

I knew the M985 crank had a small q-factor, but I was surprised to see how small the clearance was! I can see these cranks wouldn't be compatible with a lot of frames eh?


Top
 Profile  
 
PostPosted: Tue Jan 31, 2012 9:38 pm 
Offline

Joined: Tue Jan 31, 2012 9:35 pm
Posts: 6
just bought the same cranks, and my clearance is even less. 2mm max. don't know if it functionally matters, but just looking at it is a bit disconcerting. do you notice that your non-drive side has more clearance? the difference is noticeable on mine.


Top
 Profile  
 
PostPosted: Tue Jan 31, 2012 11:25 pm 
Offline

Joined: Wed Sep 16, 2009 10:25 am
Posts: 173
Location: Australia
Gchan wrote:
just bought the same cranks, and my clearance is even less. 2mm max. don't know if it functionally matters, but just looking at it is a bit disconcerting. do you notice that your non-drive side has more clearance? the difference is noticeable on mine.


Yes, you're right the clearance on the non-drive side is about 4-5mm. Sounds like I'm not the only one then! I'm guessing this is the price you pay for a low q-factor.


Top
 Profile  
 
PostPosted: Sun Jun 24, 2012 4:20 am 
Offline

Joined: Wed Sep 16, 2009 10:25 am
Posts: 173
Location: Australia
As a follow-up to this I have noticed the drive-side crank arm on my M985 crank has a slight rub mark, as well as on the chainstay. Only very minor, but it is definitely making contact at some point.
So it seems the crank/frame is flexing and under certain conditions perhaps with additional mud there is a rub.

Not good, but do I need to worry about it? I'll post a pic.


Top
 Profile  
 
Posted: Sun Jun 24, 2012 4:20 am 


Top
  
 
PostPosted: Wed Jun 27, 2012 1:01 pm 
Offline

Joined: Thu Jul 05, 2007 10:18 am
Posts: 5
I tried fitting one (44/30T) to a Trek 9.9 (2007/8?), and the large chainring fouls the chainstay before the crank seats against the BB bearing!
It might fit if I remove the chainsuck plate, but I'm not gonna risk that!

I've now fitted it to my SC Blur XC - it's very close on that - around 2-3mm max, but does fit.

Anyone else had the same issue with other frames?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. Shimano M985 Race crank chainring question

in MTB

hjb1000

1

332

Mon Jun 23, 2014 6:55 am

rainerhq View the latest post

There are no new unread posts for this topic. NewUltimate Evo road bar - acceptable weight deviation

in Road

CGT

7

634

Wed Oct 29, 2014 12:01 pm

mjainoz View the latest post

There are no new unread posts for this topic. BMC Chainstay and Sensor compatibility

in Training

Devon

2

440

Tue Apr 08, 2014 1:28 am

Devon View the latest post

There are no new unread posts for this topic. Chainstay mounted rear brakes?

in Road

SuperDave

5

493

Sat Sep 20, 2014 2:51 am

Kayrehn View the latest post

There are no new unread posts for this topic. Scott Foil 20, 2013 chainstay protector

in Road

JasperGr

1

239

Fri Nov 21, 2014 4:24 pm

JasperGr View the latest post


It is currently Fri Dec 19, 2014 2:04 pm

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB