Rear wheel for single speed conversion
My girlfriend and I are converting her late '80s Schwinn to single speed. Because the steel rims are having trouble braking even when dry, we are going to get new wheels. My question is should we get a single speed wheel or a multi-speed one? I am leaning toward multi because we are building this on a budget and I'd rather use spacers to get the chainline than switch out bottom brackets, etc. Is there a way to get a good chainline without that? Thanks in advance for the help.
surly old man
Its complicated. There are two factors, of course, in determining chainline: where the chainring is in front and where the cog is on the rear. Those two factors break down into several more factors. On the rear, you can flip the cog and sometimes move it in or out, or put a spacer behind the cog. Most importantly, you can move the cog around a lot by choosing how to respace the rear wheel. On the front, you can put the ring on the inside or outside of the spider, or use spacers to push it farther in or out. A different length spindle, or a different crank will also move the chainline around. Lastly, it used to be the custom to have asymmetrical spindles (longer on one side than the other), so you can move the line quite a bit just by flipping it around.
Its complicated, but not hard to mess with most of these factors. Trial and error is maybe the most efficient way to do it.
Do keep in mind that a new single speed wheel will not solve the problem for you by itself. They come set up for a chainline that your spindle/crank cannot achieve without further modification. So, even if you go that route you will have to mess with some of those factors.
My recommendation is to use the current wheel (I presume it is a freewheel?) and try to bring the rear out as much as possible by respacing and redishing. Then hope that you can bring the front in as much as possible by putting the ring on the inside of the ring and maybe using spacers on the bolts. You have a good chance of this working without needing a new BB spindle. You will likely have to do all of this with a purpose-built single speed wheel anyway, so if the current wheel is in decent shape, you might just as well use it.
None of this beyond an interested tinkerer, or none of it is terribly expensive.
jgedwa pretty much covered everything you need to know but if you're building a single speed as opposed to a fixed gear bike a multi-speed freehub rear wheel would be the easiest choice. You should be able to just add spacers on the freehub to get a single cog out where you want it. An inexpensive (or used) freehub wheel is also easier to find than its single speed equivalent.
I did a conversion similar to this for my dad. I replaced the steel wheel with a no name machine built aluminum wheel with an 8 spd. freehub, a stack of spacers, and a Surly cog. I ended up getting a multi-speed wheel to give him options. If he wanted to he could replace the spacers/cog with a cassette, add a derailler, etc. and have a 1x8 bike. Also I was able to use the existing BB and get a solid chainline. Total cost ~ $75.
Originally Posted by Blinksaw182
Thanks for all the help. I've decided to get the cassette ready wheel which you guys all recommended. Hopefully that will keep costs down and allow us to reuse as many parts as possible. Thanks again.