Let me start by saying that there was nothing intrinsically wrong with my Wabi Cycles Special drive train. I like to tinker with my bikes, so when I wanted to change the gearing of my Wabi Special, I decided to change a few other things too!
New drivetrain on my Wabi Special
The upgrades that you are looking at are:
- Wabi Cycles 52 tooth 144 BCD chainring.
- White Industries 17 tooth ENO freewheel
- KMC Z610 HX silver chain 3/32″
- Shimano square BB-UN55 bottom bracket 68x110mm.
The 52/17 gearing (80.4 gear inches) is effectively the same as 46/15 gearing (80.6 gear inches). I now have singlespeed bikes with 46/17, 46/16 and [effectively] 46/15 gearing. While it may not seem a large difference in gears, over the course of a 40 km ride one tooth on the rear sprocket does make a difference.
When I fitted the 52 tooth chain ring, there was only a couple of millimetres clearance from the chain stay. Owner of Wabi Cycles Richard Snook said in an email to me that this is plenty of clearance. According to my straight edge, the chain line was also out by about ~4 mm. Richard Snook’s web site in the Wabi Cycles 18/16 Dual Fixed Cog product description indicates that 3/32″ chain has plenty of flexibility to handle a few millimetres of lateral positioning. These bikes are set up with 3/32″ chain, which is typically used on multi-speed bikes. A couple of millimeters is therefore no big deal.
For me, I decided to increase the chain ring clearance while correcting the chain line. The KMC Z610 HX chain, while being 3/32″, is also an anti-drop design, meaning it is not intended for multi-geared bikes which by their nature are intended to de-rail while changing gears.
The bottom bracket as supplied on my Wabi Special was a 103 mm unit. Doing the calculations (and assuming that the extra length would be equally distributed on both sides), 110 mm was a better bottom bracket length.
According to the Wabi Cycles web site, the cranks supplied are Andel RSC1-7102 cranks. Somewhere in a back corner of the internet I read that Andel recommend a 110 mm bottom bracket for these cranks to achieve a ~42 mm chain line. However, apparently this offsets the left crank a little. While I was unable to verify this with any technical documents on the internet, word is that a 107 mm Shimano bottom bracket has the same spacing on the right, but is slightly narrower on the left than a 110 mm Shimano bottom bracket. While this does not seem logical given other comments on bottom brackets, my 110 mm bottom bracket certainly sets the left hand crank a couple of millimeters wider than the right crank! Go figure.
(Update: I recently put a set of Andel RSC1 cranks on another one of my bikes using a Shimano BB-UN55 107 mm bottom bracket. The cranks appear to be perfectly centered, so it appears that the 107 mm bottom bracket is the best one to use with these cranks.)
With my upgraded drivetrain, I have created a new problem. My Wabi Special is now too fast for several sections of my regular ride! — particularly the cycle way sections between Toowong and the University of Queensland. I now understand why faster cyclists choose to ride on the road on this section of the Brisbane River loop.
For more information on my Wabi Special, explore this tag, or this tag on my other blog.