monsterlikerawr

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.

Grand Bois

You should be able to obtain perfect chainline. Whoever told you otherwise is wrong. Before you do anything, read this:

https://sheldonbrown.com/singlespeed.html

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.

peripatetic

I've done this several times following the step-by-step process on Sheldon Brown's website. It works quite well.

monsterlikerawr

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?

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.

operator

Uh not necessarily, some crank/frame/wheel combos just won't work. Triply true for conversions.

Zouf

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.

Grand Bois

For instance?

peripatetic

I've never had a problem. All you need is the right spacers in back or spacers in front.

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?

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?

monsterlikerawr

what do you mean by a shorter bottom bracket?

sorry if these questions seem stupid, i just dont really know much about bikes.

peripatetic

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.

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?

sivat

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.

sivat

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.

Retro Grouch 

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.

peripatetic

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.