Frame mods for ss/fixed
 

Hi guys, I'm thinking of converting an old Trek 720 (maybe 820?) multi-track hybrid into a cyclocross/road/commuter bike that is ss/fixed and I am wondering which style of dropouts would be best for a mostly road ss, campy or rear facing horizontal? What are some of the pitfalls, or things I should watch out for once I decide which dropouts are best. I'm a machinist and a couple of my friends are excellent welders, but I've never cut up a bike frame before, so any tips or tricks would be appreciated. It's a steel frame with 700c wheels and I know I may have to spread the rear stays depending on my hub choice, if that helps. Also, any hints on modifying cranks and rim choice (cxp33?) would be great. I would like to keep it relatively inexpensive.

Thanks,

Noloft

I'd go for horizontal dropouts, if you plan to be able to pull the wheel easily on the road. If you go with track-ends (that's what the rear-facing ones are called...), you'll have to pull the chain off before removing the wheel. Tyre changes are much quicker with old-fashioned dropouts.

Why replace the dropouts when you can get any number of ss chain tensioning devices that eliminate that need? I'm partial to the one Soulcraft makes. It doesn't operate on spring tension so it doesn't bounce around on you, and it's got a nice little lever you can use to lock it in its set position once you find the proper chain tension. From there you can flip it out of the way to remove the wheel. It's always good to use either a bash guard or ss-specific chain guard to stiffen up your cranks when you're only mounting one ring. My rim of choice would be the Sun ME-14. High qualtiy, relatively light, and backed by great people.

those chain tensioners (surly singulator, etc.) are only an option if he's going with a regular singlespeed setup, and NOT a fixed gear setup. you can tear one of those right off if you use it with a fixed gear as soon as you try to put any real amount of back pressure on it.

I would say most older bikes had the horizontal dropouts you need, a holdover from the days before quick release wheels. You probably don't need to modify the frame. The old Trek I just put a fixed gear on had horizontal dropouts. So do my old Bianchi and Schwinn Voyageur.

I agree with D*Alex, horizontal dropouts are more practical and convenient than track 'fork ends'. Doesn't the frame you are using does have horizontal dropouts resembling the red one at
http://www.sheldonbrown.com/gloss_d.html#dropout ?

Track hubs are usually narrower in outer locknut spacing (110 or 120). I spaced my 110 Sovos out to 126 without needing to change the axle. The only annoyance is that the chainline is very narrow (this is on an old mountain bike frame). Phil Woods are probably the ultimate and come in many different spacings.

There should be no need to change cranks. Using the same bottom bracket, at the very least you will need to locate the chainring in the middle position of your cranks. In my case, I also had to use spacers to get the ring even further in, even with a short BB because of the cranks I was using.

Rim choice is definitely a matter personal preference. If you want to save money, boring, basic polished rims from companies who don't market as heavily as Mavic can't be beat. Many people prefer to pay the extra for Mavic and that's fine too. If you aren't using brakes on the back, the rim should last for a long, long time.

If you haven't already, have a look at http://www.sheldonbrown.com/fixed.html , lots of useful information.

Bikerider
I am undergoing a conversion as well to fixed. My dropout spacing is 126. From your experience, with respect to chainline, how important is hub dimension? The hub I was thinking of using is spaced for 120. I know I can add a spacer to both sides to get the 126, but this does not affect chainline as I understand it. I want to end up with a non-dished flippable wheel- double fixed. I am looking for a new BB to complement whatever hub I decide to use, but would like to have as straight a chainline as possible since I am replacing the whole drive train, including adding Dura-Ace vintage track cranks. the Phil Woods is the only hub that I can find that has a 126 spec. Am I right in thinking that this moves the cog more to the right, which would allow for less alignment problems, and add to a stronger hub since the bearings are more to the outside of the wheel? Thanks in advance.

Barnaby,

Spacing the 120 to 126 will be fine. Because I was using a 110 on a MTB, using a 107 BB wasn't enough and I had to use spacers between the chainring and crank, which bothers me. I do like the small 'Q' factor, however.

The Phil Woods come pre-spaced but I don't think that they flange, cog or bearing spacing is different for the 120/126/130. This would add a lot of cost and it really isn't necessary. Just the fact that the wheel is symmetrical gives you plenty of strength.

Your original plan sounds the best and you seem to know what you are doing. Now that I have decided that I really like the fixed gear, I also will get a double fixed 120 and space that.

Have fun!

My mistake, I interpreted his thoughts to be ss OR fixed. Obviously chain tensioners are no good with a fixed gear.