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 03-31-12, 10:24 PM   #1
Telly
What, me worry?
Thread Starter
 
Telly's Avatar
 
Join Date: May 2011
Location: Athens, Greece
Bikes: Corratec / Jamis
Posts: 1,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Can this be done: Changing from a compact 3-disc crankset to a 2-disc crankset?

Hello everyone,

After having broken in my new bike with nearly 1000 commuting miles on it, I've come to the conclusion that the stock 3-disc crankset (22/32/42) gearing is too short for my needs, and that the best setup would be a 2-disc set with 32/50 gearing or something close to that.

Can I somehow install a 2-disc cankset AND keep all the existing hardware such as the 3x8 Shimano shifters (see pic), stock front(Alfine)/rear(Deorde) derailleurs (again see pics) and Shimano UN26 (68x113) square taper bottom bracket and rear 11/32 cassette?

Also if the above is somehow possible, which crankset would you recommend?

-OR- would it be possible to change the chainrings on the existing FSA/RPM AL-8 crankset to a range more compatible to what I need? (mind you, that I have checked around for a 24/34/48 crankset and found some cheap units which my LBS didn't recommend.)



Attached Images
File Type: jpg Shifters.jpg (20.8 KB, 12 views)
File Type: jpg Geartrain.jpg (80.0 KB, 16 views)

Last edited by Telly; 03-31-12 at 10:27 PM.
Telly is offline   Reply With Quote
Old 03-31-12, 11:51 PM   #2
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
Posts: 7,099
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Maybe you could find an adapter that lets you mount a 130mm PCD road ring? That'd be the simplest way by far.

I'd be loathe to change the cranks, to the point that if I couldn't find such an adapter, I'd look at having one made. Have to be cheaper than a crankset.

Only downside would be the lift pins/shift gates would be intended for a bigger ring than 32t, but I bet it'd still shift better than a plain ring.
Kimmo is offline   Reply With Quote
Old 04-01-12, 12:41 AM   #3
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,870
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 229 Post(s)
Dump the BB too, for a shorter one = to losing the 1 chainring.
fietsbob is offline   Reply With Quote
Old 04-01-12, 12:48 AM   #4
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
Posts: 7,099
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Oh yeah, your MTB FD almost certainly won't work with a 50t; might wanna check out this thread.

To answer your question, changing the cranks will require a BB and prolly FD. RD will be fine, although the cage will be longer than required; a road derailleur might be slightly better but is hardly necessary.
Kimmo is offline   Reply With Quote
Old 04-01-12, 01:20 AM   #5
Telly
What, me worry?
Thread Starter
 
Telly's Avatar
 
Join Date: May 2011
Location: Athens, Greece
Bikes: Corratec / Jamis
Posts: 1,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This thread is starting to sound expensive... what if I could find a Deore/XT 24-38-48 Crankset (relatively cheap on the net) and pair it with a Deore XT 8-speed IG 11-28 cassette, would that setup work with the currently installed derailleurs and shifters?

Found this: Alivio FC-M-411 48/38/28 and it says that I need a B/B with axle length 122mm instead of the 113mm that's already installed.

...also this: CS-HG 70 8SP 11-28

Last edited by Telly; 04-01-12 at 01:27 AM.
Telly is offline   Reply With Quote
Old 04-01-12, 01:59 AM   #6
Bill Kapaun
Senior Member
 
Bill Kapaun's Avatar
 
Join Date: Feb 2007
Location: Mid Willamette Valley, Orygun
Bikes: 86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.
Posts: 9,201
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Get a 12-21 cassette and learn to spin!
Bill Kapaun is offline   Reply With Quote
Old 04-01-12, 06:00 AM   #7
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Rans Rockst (Retro rocket) Rans Enduro Sport (Retro racket) Catrike 559, Merin Bear Valley (beater bike).
Posts: 26,543
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 62 Post(s)
When I originally built my recumbent I put a 22/32/42 crankset on it because that's what I had in my spares box. Shortly thereafter I bought a 48 tooth big ring and installed it giving me a 22/32/48 crankset. All that I had to do was to raise the front derailleur a little and lenghten the chain a little. Shifting was fine, but I use friction barcons for the front chainrings.

Riding-wise it was great. The 48 tooth chainring gave me more top end speed than I normally use. I did almost all of my riding in the big ring and only shifted down into the middle ring steep hills. I thought of it as a 48/32 compact crankset with a granny bail out gear (which I never used).

Relative inexpensive too.
Retro Grouch is offline   Reply With Quote
Old 04-01-12, 08:19 AM   #8
Telly
What, me worry?
Thread Starter
 
Telly's Avatar
 
Join Date: May 2011
Location: Athens, Greece
Bikes: Corratec / Jamis
Posts: 1,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Bill, you want to spin me into an early grave! lol (don't forget, I'm a big Clyde!)

So what you're saying Retro is basically changing the front Crankset (can't find just the chain ring, already looked!). I remember bringing this up again in the past, and will probably proceed in getting a 28/38/48 like the one in the link in my previous post.
Telly is offline   Reply With Quote
Old 04-01-12, 09:07 AM   #9
jethro56 
Watching and waiting.
 
jethro56's Avatar
 
Join Date: Oct 2010
Location: Mattoon,Ill
Bikes: Trek 7300 Giant Sedona E-Bike Trek Madone 4.5 Surly Cross Check
Posts: 1,998
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
That 16 tooth jump from a 34 to a 50 on a compact crank is a slow shift. I know it's made me appreciate being able to spin at high cadences in the low chainring just to avoid it if I won't be in it for awhile. Going clipless has cut back on the amount of front shifting I need to do.
jethro56 is online now   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 02:09 PM.