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 06-08-09, 07:31 PM   #1
GrannyAbuser
Junior Member
Thread Starter
 
Join Date: May 2009
Location: Haverhill MA
Bikes: Surly Instigator/Bridgestone MB-4/Raliegh Technium
Posts: 9
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
"Hybrid-izing" a MTB Chainring limits?

I'm converting a 1992 Bridgestone MB-4 into a fat man's touring bike. What is the biggest functional triple anyone has put on one of these? Also, will I need a different front derraileuer?
GrannyAbuser is offline   Reply With Quote
Old 06-08-09, 08:05 PM   #2
relyt
Senior Member
 
Join Date: Jan 2004
Bikes:
Posts: 619
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Most of that depends on how your derailer mounts. If it is on a braze-on mount, you can't move it up to accomodate larger chainrings. In that case, you could probably file off the braze-on, or just ignore it, and get a clamp-on derailer.

If your derailer clamps on, then you can slide it up to make room for the larger chainrings.

On some bikes, the chainstays flare out quite a bit, and you should check to make sure that a larger chainring won't hit them. That is a very rare problem, though, and you should be fine.

If you can get around any of the issues I mentioned, then you could put pretty much any chainrings on that bike. I think that 48/38/28 or something like that is good for touring. It is higher than mountain gearing, but lower than road gearing. (Actually, I have a 48/36 double on my "road" bike, and that is plenty high. The big 53-tooth ring on most road bikes doesn't get used to its full potential unless riding very fast downhill.) You should probably stick with the mountain bike rear gearing for touring.
relyt is offline   Reply With Quote
Old 06-09-09, 08:32 AM   #3
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Bikes: Some silver ones, a black one, a red one, an orange one and a couple of titanium ones
Posts: 17,965
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 165 Post(s)
Quote:
Originally Posted by GrannyAbuser View Post
I'm converting a 1992 Bridgestone MB-4 into a fat man's touring bike. What is the biggest functional triple anyone has put on one of these? Also, will I need a different front derraileuer?
A trekking crankset (48/36/26) paired with an 11-34 cassette will give you just about all the gears you'll need for a touring bike. I'd probably go with a 22 inner...but that's just me

The MB-4 has a clamp-on derailer and the 1993 version came with a 46 outer ring so a 48 shouldn't have problems with hitting the chainstay.
__________________
Stuart Black
New! Pokin' around the Poconos A cold ride around Lake Erie
New! Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.
cyccommute is offline   Reply With Quote
Old 06-09-09, 02:53 PM   #4
dabac
Senior Member
 
Join Date: Mar 2008
Bikes:
Posts: 5,412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Quote:
Originally Posted by GrannyAbuser View Post
I'm converting a 1992 Bridgestone MB-4 into a fat man's touring bike. What is the biggest functional triple anyone has put on one of these?
Particularly with your sig, why do you think you need a bigger crank? Far more people would benefit more from working to improve their cadence than from buying bigger cranks. For commuting and touring, actually spinning out is/should be a quite rare occurrence. I know I don't do it, and if I don't, then the people I overtake or keep pace with certainly aren't either.
dabac is offline   Reply With Quote
Old 06-09-09, 09:20 PM   #5
GrannyAbuser
Junior Member
Thread Starter
 
Join Date: May 2009
Location: Haverhill MA
Bikes: Surly Instigator/Bridgestone MB-4/Raliegh Technium
Posts: 9
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by dabac View Post
Particularly with your sig, why do you think you need a bigger crank? Far more people would benefit more from working to improve their cadence than from buying bigger cranks. For commuting and touring, actually spinning out is/should be a quite rare occurrence. I know I don't do it, and if I don't, then the people I overtake or keep pace with certainly aren't either.
You have a valid piont dadac however I have always been a torker rather than a spinner. since I'm fat and extremely slow up hills I have found that my best tactic is to attack the downhills where gravity is my friend which gets me that much further up the next hill. I've always referred to this as "getting up on plane" and have found this to be the best way (short of losing weight) to up my average speed and conserve my energy.

I have a road bike (Raleigh Technium 753 or 531 [trying to determine that in another thread]) which is a rocket ship with its tall gearing, but is a poor choice for me right now with a double rather than a triple plus I'm afraid of hurting it at my current weight. I also have an ultra heavy duty Surly Instigator for the woods which I won't hurt but is like a Hummer on the street and tires me out.

Lastly I have my MB-4 that I've decked out for comfort and utility and I'm trying to split the difference in gearing and make it my road bike until I get back to a more reasonable weight. Both MTB's have 22/32/42 cranksets and I spin out (my max comfortable cadence is probably 80-ish) on downhills even with the 11-32 cassette. The bike originally came with a 26/36/46 crankset which I broke years ago and then years later I had an LBS replace the bottom bracket. I have an old Sugino 28/38/48 crankset which I tried to put on there but it bottomed out on the frame when trying to tighten it.

I would think that if the bike came with the 46 tooth setup a 48 tooth setup should fit, but it's possible the LBS installed a narrower one than original. I'll have to take some measurments. I just figured I'd post this question before needlessly spending $ on "upgrade parts".

Worst case scenario: I'll deal with the shorter gearing, learn to spin better and/or start embracing uphills as "weight training".
GrannyAbuser 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 05:52 PM.