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Old 06-12-05, 05:08 AM
  #1  
Lobalobo
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Having done nothing more challenging than changing tires before and adjusting old centerpull brakes, I've decided to take a leap and build up a single-speed mountain bike (conversion) from frame and components bought on ebay. I have a copy of Zinn and a set of tools but am definitely beyond my ability. Could ask some questions at my local bike shop, but they are there to make a living, not tutor me, so I thought I'd try this site. Here are a few start-up questions, and my appreciation in advance for anyone who is willing to take the time and answer:

1. Bought a Truativ crank with a single 38t ring and a bash-guard; it came packaged with (what I think is) a Shimano clone cartridge type bottom-bracket, 113mm length. Installation in my aluminum frame looks simple (even for me) but immediately face an unbelievably basic question. I assume that I should put grease on the threads before installing, but Zinn doesn't say to do this (though it mentions grease elsewhere in the book). Can't imagine getting the BB in without grease, even though I have the right BB tool, but thought I'd make sure this is right. (Also, I have the same question regarding V-brake posts, which I need to buy and install as the frame came without the posts.)

2. Once the bottom bracket and crank are in, the next thing I worry about is chainline. I'm going to get a freehub rear wheel that takes a cassette cog-set then use a single-speed conversion kit with spacers and an 18t cog. The question here is whether the chainline will be right even with the rear cog as close as possible to one side of the hub. Is this something I should worry about, or is the 113mm bottom bracket and standard freehub setup flexible enough that this will definitely work? If there is something to worry about, what measurements on the frame/crank do I need to make?

Thanks in advance, and if this works my next questions will be about chain tensioners (vertical dropouts) and chain installation.
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Old 06-12-05, 07:59 AM
  #2  
Nessism
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Grease the canti. posts and BB before installation. No grease on the crank spindle assuming it's a square taper version.

I don't think you can add canti. posts to a frame however - these are not bolt on parts. Many MTB frames these days are set up for disk brakes so the canti. posts many have been left off for a reason.

As far as the rear cog goes, I think you want the cog in the middle of the freehub body to keep the chain line correct. I've never messed around with conversion stuff though so I may be wrong.

Good luck.

Ed

Last edited by Nessism; 06-12-05 at 08:07 AM.
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Old 06-12-05, 08:26 AM
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geopolitical
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1. Actually it depends on what your bb and shell are made of, at least from what the "official" people always tell me. It's supposed to be "grease or anti-seize" on aluminum or titanium shell bb and loctite on steel ones. *edit* man I have no sleep. Grease it is. You're on aluminum.

I would really recommend you pick up a cheap torque wrench at this point however. Some of the relatively accurate "click" ones are as low as $20 these days and it sure l beats a part coming loose or stripping threads. Ebay is an excellent source (I really like the "angry ex wife sales").

V brake posts, I lightly grease the posts themselves and put some loctite on the bolts that secure the levers to them. I really doubt you can get anyone to weld you on a pair of posts to an aluminum frame at this point if it doesn't have them to begin with. I'd just set it up for disc brakes if that's all the frame has. Both Avid and Shimano have some awfully cheap mechanicals on the market if you're looking at it from a budget perspective.

2. If you're going for a single speed conversion kit it should have enough spacers with it to allow you to set up a near perfect chainline. I personally wouldn't worry about it at this point as I haven't yet seen a kit that wouldn't allow a huge variation in where the cog was placed. My first SS buildup I used a chunk of PVC and then just placed the chain over it, sharpie marked it when I had the chainline right and cut it through with enough width to fit the cog. It was cheap and so am I. I really can't recommend the method unless you're dirt broke however, I found out the hard way that PVC can shatter fairly easily in the cold.

Last edited by geopolitical; 06-12-05 at 08:33 AM.
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Old 06-12-05, 10:14 AM
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Lobalobo
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Thanks to both of your for responding so quickly. One anwer I didn't expect was the one about the V brake posts. The frame doesn't have any, but does have threaded holes where one would expect the posts to be. I have assumed those were for screw-in posts. Is this wrong?
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Old 06-12-05, 10:17 AM
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Lobalobo
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Sorry to repeat the reply to the prior reply, but on the chance you are monitoring your own reply only: Thanks to both of your for responding so quickly. One anwer I didn't expect was the one about the V brake posts. The frame doesn't have any, but does have threaded holes where one would expect the posts to be. I have assumed those were for screw-in posts. Is this wrong?
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Old 06-12-05, 10:55 AM
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matheprat
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No, you're correct. You need 2 V brake posts, which simply screw into the threaded holes you have on you're frame. Locktite these in, don't use grease (at least that's what i'd do)
Cheers
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