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 10-25-06, 12:00 PM   #1
monsterlikerawr
Junior Member
Thread Starter
 
monsterlikerawr's Avatar
 
Join Date: Oct 2006
Location: san francisco
Bikes: lotus odyssey. single speed.
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
converting to a single speed

so i just started converting my lotus odyssey to a single speed and i was wondering if there was any advice as to what i should do...
it is my understanding that i will have to live with the chain being at sort of an angle and it wont be perfectly aligned with my crank... is there any possible way to make it straight other than making my rear wheel off center?

thanks for any advice.
monsterlikerawr is offline   Reply With Quote
Old 10-25-06, 12:23 PM   #2
Grand Bois
Senior Member
 
Grand Bois's Avatar
 
Join Date: Mar 2005
Location: Pinole, CA, USA
Bikes:
Posts: 16,569
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
You should be able to obtain perfect chainline. Whoever told you otherwise is wrong. Before you do anything, read this:

http://sheldonbrown.com/singlespeed.html
Grand Bois is offline   Reply With Quote
Old 10-25-06, 12:33 PM   #3
San Rensho 
Senior Member
 
Join Date: Oct 2005
Bikes:
Posts: 5,540
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
I'm assuming that you are using the existing freewheel and crank and just removing the rear der and shortening the chain.

First, ride the bike on the small chain ring. Find the gear that is most comfortable for you for most situations. Now, count the teeth on the CR and the cog you are using and determine, using a gear chart, how many inches it is.

Now look at the gear chart and find the equivalent cog for your big chainring. Select that combination and select the one that gives you a better chain line. You should have a fairly good chain line with one or the other.
__________________
Il faut de l'audace, encore de l'audace, toujours de l'audace

1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1
San Rensho is offline   Reply With Quote
Old 10-25-06, 08:25 PM   #4
peripatetic
Senior Member
 
peripatetic's Avatar
 
Join Date: Oct 2004
Location: NYC
Bikes: All 70s and 80s, only steel.
Posts: 2,124
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've done this several times following the step-by-step process on Sheldon Brown's website. It works quite well.
peripatetic is offline   Reply With Quote
Old 10-26-06, 01:12 AM   #5
monsterlikerawr
Junior Member
Thread Starter
 
monsterlikerawr's Avatar
 
Join Date: Oct 2006
Location: san francisco
Bikes: lotus odyssey. single speed.
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by San Rensho
I'm assuming that you are using the existing freewheel and crank and just removing the rear der and shortening the chain.

First, ride the bike on the small chain ring. Find the gear that is most comfortable for you for most situations. Now, count the teeth on the CR and the cog you are using and determine, using a gear chart, how many inches it is.

Now look at the gear chart and find the equivalent cog for your big chainring. Select that combination and select the one that gives you a better chain line. You should have a fairly good chain line with one or the other.
i was actually thinking of buying a new single speed freewheel.. i heard they arent too expensive, although i havent looked at prices myself.

what do you think is the best way to go about converting a multispeed to a single speed?
monsterlikerawr is offline   Reply With Quote
Old 10-26-06, 01:25 AM   #6
sivat
Geek Extraordinaire
 
sivat's Avatar
 
Join Date: Feb 2006
Location: Long Beach, CA
Bikes: Bianchi Advantage Fixed Conversion; Specialized Stumpjumper FS Hardtail
Posts: 1,769
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It depends what kind of rear hub you have now. If it uses a threaded on freewheel, buying a single speed freewheel is about $20. You can fix the chainline by either using the inside position on the crank or getting a shorter bottom bracket. If you have a freehub, you can just use spacers to remove the other cogs and make a single speed.
__________________
I'd rather have a bottle in front of me than a frontal lobotomy.

Sintesi Conversion Serotta Track
sivat is offline   Reply With Quote
Old 10-26-06, 07:51 AM   #7
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Dirtdrop
You should be able to obtain perfect chainline. Whoever told you otherwise is wrong. Before you do anything, read this:

http://sheldonbrown.com/singlespeed.html
Uh not necessarily, some crank/frame/wheel combos just won't work. Triply true for conversions.
operator is offline   Reply With Quote
Old 10-26-06, 10:42 AM   #8
Zouf
Senior Member
 
Join Date: Aug 2004
Bikes:
Posts: 736
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by sivat
It depends what kind of rear hub you have now. If it uses a threaded on freewheel, buying a single speed freewheel is about $20. You can fix the chainline by either using the inside position on the crank or getting a shorter bottom bracket. If you have a freehub, you can just use spacers to remove the other cogs and make a single speed.
You can convert either a freehub/cassette (by picking which cog you want to use, and placing spacers around it to put in into the right chainline), or a freewheel (by taking apart the cogs on the freewheel with 2 chainwhips, picking which cog you want to use, and placing spacers inside as required to get the right chainline). In both cases, it is not necessary to by a single-speed freewheel, and generally not needed to move axle spacers + re-dish the wheel. Also keep open the option of moving the chainring to the "inside" position on the crank, i.e. where the mid or small (for 3- or 2-chainring installs) was previously located, to help bring the chainline inwards. This is particularly useful when starting with a triple crank, if you don't want to replace the bb axle.
Zouf is offline   Reply With Quote
Old 10-26-06, 11:26 AM   #9
Grand Bois
Senior Member
 
Grand Bois's Avatar
 
Join Date: Mar 2005
Location: Pinole, CA, USA
Bikes:
Posts: 16,569
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
Quote:
Originally Posted by operator
Uh not necessarily, some crank/frame/wheel combos just won't work. Triply true for conversions.
For instance?
Grand Bois is offline   Reply With Quote
Old 10-26-06, 11:31 AM   #10
peripatetic
Senior Member
 
peripatetic's Avatar
 
Join Date: Oct 2004
Location: NYC
Bikes: All 70s and 80s, only steel.
Posts: 2,124
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by operator
Uh not necessarily, some crank/frame/wheel combos just won't work. Triply true for conversions.

I've never had a problem. All you need is the right spacers in back or spacers in front.
peripatetic is offline   Reply With Quote
Old 10-31-06, 12:27 AM   #11
BROCK SAMPSON
rules the earth
 
BROCK SAMPSON's Avatar
 
Join Date: Sep 2006
Location: melbourne,Australia
Bikes: norco kompressor 06, DK general lee
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Sorry if I'm changing the subject a bit, but I'm converting to a sinlgespeed too and I was wondering if, to change the front shifter, could you keep the bb and just change the crank arm that the chanrings are on?or would you have to change the whole setup?
BROCK SAMPSON is offline   Reply With Quote
Old 10-31-06, 02:36 AM   #12
monsterlikerawr
Junior Member
Thread Starter
 
monsterlikerawr's Avatar
 
Join Date: Oct 2006
Location: san francisco
Bikes: lotus odyssey. single speed.
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
heres my progress so far:
-ive found that once i try to fix one thing and get that all squared away, i find something else that needs to be fixed before i can continue...
-i rebuilt my bottom bracket and i removed one of the chain rings so im good on the front
-i got a single speed freewheel. i started to put it on and then i realized that my rear hub was grinding. so i started to take that apart and i plan on rebuilding that in the next couple of days.
-after i put the freewheel on i need to buy a new chain cuz my current ones a bit rusty.

so... how do i go about finding the right chain?
monsterlikerawr is offline   Reply With Quote
Old 10-31-06, 02:39 AM   #13
monsterlikerawr
Junior Member
Thread Starter
 
monsterlikerawr's Avatar
 
Join Date: Oct 2006
Location: san francisco
Bikes: lotus odyssey. single speed.
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by sivat
I You can fix the chainline by either using the inside position on the crank or getting a shorter bottom bracket.
what do you mean by a shorter bottom bracket?

sorry if these questions seem stupid, i just dont really know much about bikes.
monsterlikerawr is offline   Reply With Quote
Old 10-31-06, 07:22 AM   #14
peripatetic
Senior Member
 
peripatetic's Avatar
 
Join Date: Oct 2004
Location: NYC
Bikes: All 70s and 80s, only steel.
Posts: 2,124
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by monsterlikerawr
heres my progress so far:
-ive found that once i try to fix one thing and get that all squared away, i find something else that needs to be fixed before i can continue...
-i rebuilt my bottom bracket and i removed one of the chain rings so im good on the front
-i got a single speed freewheel. i started to put it on and then i realized that my rear hub was grinding. so i started to take that apart and i plan on rebuilding that in the next couple of days.
-after i put the freewheel on i need to buy a new chain cuz my current ones a bit rusty.

so... how do i go about finding the right chain?

Look at the teeth on your freewheel: if they're thicker than what you've seen on a road bike, then you need to get a 1/8" chain. Otherwise, you can use any normal road chain. If it's used, it's not a big problem because chain 'stretch' will not be affecting any gear changes/derailers. You will just want to make sure that the chain is taut and the rear wheel is pulled back enough. I believe the accepted rule-of-thumb is that you should be able to lift the chain no more than 6", though I might have this number wrong. You don't want it too tight, however, because then the cranks/wheel won't turn freely.

I've never really encountered this problem.

The only thing you might care about w/r/t the chain size is that if you have a 1/8" chain on a road chainring in the front, you'll get some side-to-side play, which in practice won't cause any problems, but it'll be a bit rattly. The analist in many of us (i.e. me ) doesn't like such half-measures, but the economist in others might feel it's best to make due with what you have.

You can use your old chain, as long as it'll fit on the teeth of the freewheel.

As far as the bb goes, he meant to say maybe your bottom bracket <i>spindle</i> was too long. That's the metal rod to which the cranks attach. From my experience, the easiest way to address chainline is via the rear wheel and hub axle spacers. Provided you have a good variety of 1-3mm spacers, it shouldn't be difficult getting it w/in 1mm, and that's plenty good enough for a ss conversion.

Good luck and have fun. Post pics when you've finished. I love ss bikes: easiest way to make a friend fall back in love with bicycles.
peripatetic is offline   Reply With Quote
Old 11-06-06, 12:41 AM   #15
monsterlikerawr
Junior Member
Thread Starter
 
monsterlikerawr's Avatar
 
Join Date: Oct 2006
Location: san francisco
Bikes: lotus odyssey. single speed.
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
i just finished the conversion but the chainline is still off
i was told that because my hub is not on made for a cassette, but rather a freewheel that i wont get a straight chainline because theres no room for spacers... or at least not enough. i'll try to post some pictures of the problem soon. maybe thatll help.


but, for now since im under the impression that i cant get a straight chainline... whats the worst that can happen if i try to ride on my bike now?
monsterlikerawr is offline   Reply With Quote
Old 11-06-06, 01:30 AM   #16
sivat
Geek Extraordinaire
 
sivat's Avatar
 
Join Date: Feb 2006
Location: Long Beach, CA
Bikes: Bianchi Advantage Fixed Conversion; Specialized Stumpjumper FS Hardtail
Posts: 1,769
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by monsterlikerawr
what do you mean by a shorter bottom bracket?

sorry if these questions seem stupid, i just dont really know much about bikes.
When you buy a bottom bracket, there are 3 things to look for. The first is the interface, or type of bottom bracket. The most common for modern stuff is square taper (most common), ISIS or shimano's Octalink. When you look at a square taper bb, it will usually say something like 68x103, or 70x113. The first number width of the bottom bracket shell in mm. Most road bikes that are not italian are 68mm. The second number is the length of the bottom bracket spindle. It determines how far the cranks sit away from the frame. The smaller the number, the closer together the crank arms will be and the closer the chainring will be to the frame.

As for the discussion about some bikes not being able to get a decent chainline, I don't think its true if you can use a small enough chainring. The problem comes from trying to run a big ring on a bike originally made for a triple. The chainstays don't provide enough clearance to run a big ring with a 42mm chainline. Usually, you can make it work with a smaller ring (42t or fewer) and a smaller cog.
__________________
I'd rather have a bottle in front of me than a frontal lobotomy.

Sintesi Conversion Serotta Track
sivat is offline   Reply With Quote
Old 11-06-06, 01:34 AM   #17
sivat
Geek Extraordinaire
 
sivat's Avatar
 
Join Date: Feb 2006
Location: Long Beach, CA
Bikes: Bianchi Advantage Fixed Conversion; Specialized Stumpjumper FS Hardtail
Posts: 1,769
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by monsterlikerawr
i just finished the conversion but the chainline is still off
i was told that because my hub is not on made for a cassette, but rather a freewheel that i wont get a straight chainline because theres no room for spacers... or at least not enough. i'll try to post some pictures of the problem soon. maybe thatll help.


but, for now since im under the impression that i cant get a straight chainline... whats the worst that can happen if i try to ride on my bike now?
You'll wear the chain and chainrings a bit more quickly, and it might be a bit noisy. In severe cases, you could have problems with the chain coming off, but it would have to be more than 1cm off. Try to measure the rear chainline (distance from the center of the frame to the center of the teeth.
__________________
I'd rather have a bottle in front of me than a frontal lobotomy.

Sintesi Conversion Serotta Track
sivat is offline   Reply With Quote
Old 11-06-06, 05:15 AM   #18
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)
Quote:
Originally Posted by monsterlikerawr
heres my progress so far:
-ive found that once i try to fix one thing and get that all squared away, i find something else that needs to be fixed before i can continue...
-i rebuilt my bottom bracket and i removed one of the chain rings so im good on the front
-i got a single speed freewheel. i started to put it on and then i realized that my rear hub was grinding. so i started to take that apart and i plan on rebuilding that in the next couple of days.
-after i put the freewheel on i need to buy a new chain cuz my current ones a bit rusty.

so... how do i go about finding the right chain?
Yup. It's one of those Murphy's Law things. "You can't do anything without doing something else first."

If you're using a single speed BMX freewheel you'll probably need to get a wider BMX chain.
Retro Grouch is offline   Reply With Quote
Old 11-06-06, 08:17 AM   #19
peripatetic
Senior Member
 
peripatetic's Avatar
 
Join Date: Oct 2004
Location: NYC
Bikes: All 70s and 80s, only steel.
Posts: 2,124
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by BROCK SAMPSON
Sorry if I'm changing the subject a bit, but I'm converting to a sinlgespeed too and I was wondering if, to change the front shifter, could you keep the bb and just change the crank arm that the chanrings are on?or would you have to change the whole setup?
I think you have to explain this question or re-phrase it to get a useful response. I don't understand what you're trying to figure out.
peripatetic 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 04:40 AM.