Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 08-10-10, 09:15 AM   #1
Jancouver
Senior Member
Thread Starter
 
Jancouver's Avatar
 
Join Date: Jul 2007
Location: San Diego, CA
Bikes:
Posts: 1,104
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Shimano/Sram road crank on MTB

Is technically possible to use road crank on a mountain bike?
What kind of BB do I need for Shimano Ultegra or SRAM Rival road crank to replace my 07 Giant Yukon crank/BB?
Jancouver is offline   Reply With Quote
Old 08-10-10, 09:53 AM   #2
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Bikes:
Posts: 5,982
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
Quote:
Originally Posted by Jancouver View Post
Is technically possible to use road crank on a mountain bike?
What kind of BB do I need for Shimano Ultegra or SRAM Rival road crank to replace my 07 Giant Yukon crank/BB?
You will almost certainly encounter chainstay interference with both the crank arms and the inner chain ring if you try using an external bearing type BB which cannot be adjusted for width.
If you use an older style square taper or Octalink, you have a chance by using a longer spindle.
You need a wider chainline anyway on an MTB than you will achieve with an external type road crankset.
The next issue you will face is getting a road derailleur to adjust out to work with a 50mm chainline. Some might do it, and some might not.
Dan Burkhart is offline   Reply With Quote
Old 08-10-10, 10:25 AM   #3
Jancouver
Senior Member
Thread Starter
 
Jancouver's Avatar
 
Join Date: Jul 2007
Location: San Diego, CA
Bikes:
Posts: 1,104
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Dan Burkhart View Post
You will almost certainly encounter chainstay interference with both the crank arms and the inner chain ring if you try using an external bearing type BB which cannot be adjusted for width.
If you use an older style square taper or Octalink, you have a chance by using a longer spindle.
You need a wider chainline anyway on an MTB than you will achieve with an external type road crankset.
The next issue you will face is getting a road derailleur to adjust out to work with a 50mm chainline. Some might do it, and some might not.
Thanks for the reply.
I was planning to use SRAM mtb 10 speed rear derailleur with SRAM road shifters.
Something similar to this http://velonews.competitor.com/2009/...top-fuel_96645.

Pretty much the only thing I need to figure out is the crank/bb and the FD. I can also use SRAMs 10 speed MTB crank/FD however that would add an additional cost to my project as I already have Ultegra and Rival road cranks available.
Jancouver is offline   Reply With Quote
Old 08-10-10, 10:36 AM   #4
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Bikes:
Posts: 5,982
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
Quote:
Originally Posted by Jancouver View Post
Thanks for the reply.
I was planning to use SRAM mtb 10 speed rear derailleur with SRAM road shifters.
Something similar to this http://velonews.competitor.com/2009/...top-fuel_96645.

Pretty much the only thing I need to figure out is the crank/bb and the FD. I can also use SRAMs 10 speed MTB crank/FD however that would add an additional cost to my project as I already have Ultegra and Rival road cranks available.
Interesting. I didn't want to come off as completely negative on the idea. I have done a couple of similar conversions in the past and my comments were based on my experiences.
It can be doable, but I'd look into the Q factor of the cranks and check the width across your chainstays before putting out the dough.
Also, this setup will result in a poor chainline, so you would need to be extra vigilant about cross chaining from the inner chain ring, not so much from the outer.
Dan Burkhart is offline   Reply With Quote
Old 08-10-10, 10:59 AM   #5
badamsjr
17yrold in 64yrold body
 
Join Date: May 2010
Location: Northern CA
Bikes:
Posts: 922
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Could not really tell from the pics, but for an external BB, you may have a problem. Road cranks are sized for 68mm BB shell, and MTB BB shell is normally 73mm wide. I ran into this trying to use a DA triple on a MTB frame. You might consider having your LBS face the BB shell to 68mm width (if you want to make it PERMANENT). I ended up using a different crank.
badamsjr is offline   Reply With Quote
Old 08-10-10, 02:53 PM   #6
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Bikes:
Posts: 5,982
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
Quote:
Originally Posted by badamsjr View Post
Could not really tell from the pics, but for an external BB, you may have a problem. Road cranks are sized for 68mm BB shell, and MTB BB shell is normally 73mm wide. I ran into this trying to use a DA triple on a MTB frame. You might consider having your LBS face the BB shell to 68mm width (if you want to make it PERMANENT). I ended up using a different crank.
Not always. Not even usually. Most MTBs are 68mm, 73mm is less common, but it certainly is something to check for.
5mm is a heck of a lot of material to remove with a facing mill.
Dan Burkhart is offline   Reply With Quote
Old 08-10-10, 04:12 PM   #7
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 20,431
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 656 Post(s)
certainly other ways to get a 39/30 chainring combination, like a 110/74 Mtb triple ..
or an Ultegra triple, octalink or gasp, square taper BB.
with a chain guard instead of outer ring..
2/3rds of a triple
fietsbob is offline   Reply With Quote
Old 10-02-14, 04:58 PM   #8
bobbyl1966
Senior Member
 
Join Date: Jul 2014
Bikes:
Posts: 805
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have one mountain bike trek 830 26" wheels. Now have crank 48/38/28. and 7 speeds freewheel 13-30. My top speed is go less than road bikes? If i put crank 53/39 and 9 speeds casete 12-25 my mountain bike is go have speed same or close to road bikes? Does anyone there have try that setup in mountain bike?
bobbyl1966 is offline   Reply With Quote
Old 10-02-14, 05:15 PM   #9
ThermionicScott 
Gratuitous glib and snark
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers)
Posts: 13,615
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 210 Post(s)
Quote:
Originally Posted by bobbyl1966 View Post
I have one mountain bike trek 830 26" wheels. Now have crank 48/38/28. and 7 speeds freewheel 13-30. My top speed is go less than road bikes? If i put crank 53/39 and 9 speeds casete 12-25 my mountain bike is go have speed same or close to road bikes? Does anyone there have try that setup in mountain bike?
How many times do we have to tell you that the gears aren't what make a bike "fast" or "slow" before it'll sink in? You can ask the same question over and over all you want, but it won't change that fact.
__________________
Quote:
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
RUSA #7498
ThermionicScott is online now   Reply With Quote
Old 10-02-14, 05:26 PM   #10
bobbyl1966
Senior Member
 
Join Date: Jul 2014
Bikes:
Posts: 805
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have some spare parts and i wanted tried that setup. Now that is truth the legs is be fast or not is not the bike or gears.
bobbyl1966 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 01:02 PM.