Fixie Project - Part VII

This is the final instalment in my series of posts about building a fixed-gear bike. It's the final one because ... drum roll ... it's finished! Here's what it looks like:

In the meantime, here's what else I had to do along the way:

First was modifying my rear sprocket so that the lockring would fit next to it on the hub. This basically involved removing a couple of mm from the sprocket flange with the angle grinder. The new face isn't perfectly flat, but I figure this doesn't really matter.

Next I noticed that the rear wheel bearing was a bit rough, so I dismantled it and sure enough, the LH cone was pitted. $20 at my LBS bought me an axle rebuild kit from which I used the new cones and bearing balls (I had to reuse my old axle and spacers in order to keep the same overall width). After re-greasing and re-mantling it, it now runs nice and smooth. It helped that I got a 15mm cone spanner for my birthday.

Next was fitting the sprocket and lockring to the hub. Many people on fixed.org.au recommend rotafixing the sprocket instead of using a chain whip. I used a hybrid approach: wrapping the sprocket in a short length of an old chain, clamping the wrapped sprocket into the vice, and screwing the wheel into the sprocket using the rim for leverage. I tried to get it as tight as possible without stripping the threads of the aluminium hub. Next I fitted the lockring from a bottom bracket. I used thread locker on both the sprocket and the lockring; I guess I'll find out the effectiveness of this setup once I actually get to ride the bike. If worst comes to worst, I can always buy a proper track hub for the rear wheel (or even a whole new wheel). Here's how it looks for now:

With the sprocket in its final position on the hub, it was time to check the chainline (as per Sheldon Brown's conversion article). All I needed to do was swap the wide spacer (10mm?) on the drive side (where the 7-speed freewheel used to be) with the narrow spacer (5mm?) on the non-drive side. This moved the sprocket 5mm outwards, giving a near-perfect chainline.

Respacing the rear axle meant that the rear rim was no longer on the centreline of the bike, which would make for some very interesting handling indeed. Using the process described by Tom Deakins, I only had to tighten the RH spokes (and loosen the LH spokes) a total of about 1.75 turns in order to move the rim back to the centreline. I verified this by measuring the lateral distance to the chainstays on each side of the rim. The wheel didn't seem to lose any of its trueness in the process.

After that it was just a case of shortening the chain to the right length, taping the bars, fitting the front brake, seatpost, saddle, tyres, etc. Here's another look at the final product:


Specs:

• Frame: Reynolds 501 (i.e. steel)
• Wheels: Velocity Aero (rear), Alex ? (front)
• Brake: Shimano RSX dual pivot caliper
• Lever: Tektro RX 2.0 cross top
  
• Bottom bracket: Shimano UN54 (107mm)
  
• Sprocket: Shimano Dura-Ace 7600: 16T x 3/32"
• Chainring: 42T x 3/32" @ 110 BCD on a 165mm crank
  
• Chain: SRAM 3/32" 8-speed
  
• Pedals: Shimano PD-M520 (two-sided SPD)
  

Costs:

• Parts: $426
• Shipping: $55
• Tools: $9

Overall, the build process was both fun and a good learning experience (e.g. re-dishing a wheel and replacing a wheel bearing). From a pure time and money point of view, it probably makes more sense to shell out a couple of hundred bucks more and buy a fixie off the shelf; this would result in a bike with track ends and a proper lockring hub. But it's not always about time and money, is it?