Boone rotor-mount cog
by Tom Chow


Boone bolt-on cog mounted on Tom Chow's hub

While I was spinning in to work on my fix this morning, I tried to remember the last time I serviced it. Except for the time I removed the wheel to get some pictures for the FG Gallery article, I don't think I've touched it since the time two winters ago when I first mounted the cog. That's in complete contrast with my singlespeed, whose freewheel and cartridge bearings have both had service issues. The story goes like this...

Three years ago, I was feeling a bit desperate, having stripped a few fixie hubs through a combination of questionable cogs and low gear ratios. Then I read Jason Millington's seminal article on this site. I took a front disc hub, replaced the stock axle with a 135mm rear axle, laced and re-spaced, and built it up as a rear wheel. I then took an SS cog, drilled 6 holes in it, and mounted it to the disc hub.

Well, the bolt on cog worked so well, I decided to splurge and buy the Boone Ti disc mount cog. At the time, the Boone was at the only bolt-on cog available commercially.

The Boone was fated to have a hard life. My winter commute takes in a mix of road and trails. We get rain, freezing rain and snow. Our roads that are regularly salted when the temperature drops below freezing, and sanded when it drops below -10°C. Cyclists get the resulting slushy mess of salt, sand and half-frozen water sprayed all over their drivetrains.

The trails are a lot cleaner provided the temperature stays below freezing. The bike paths and rocky singletrack are all rideable in the rain, and the rain actually washes out the road salt and cleans the bike. Sort of. (It helps if you don't mind a bit of mud.)

Since I don't have the luxury of heated water outside, or an indoor bike wash, the bike spends the winter just inside the door, thawing, dripping and drying until its next twice-daily trip. You can imagine the havoc that this treatment plays with it. Steel and aluminium parts corrode and seize to each other. I have pedals that will not come off the crank arms, spoke nipples that will not unscrew from the spokes, seatposts that have become permanent parts of the frame...

Over the years, this pitless regime has pushed me to evolve a setup that resists winter wear. Crucial elements are a Ti frame, cup-and-cone bearings, and a fixed drivetrain. The Boone disc mount cog fits right in.

Boone bolt-on cog showing one season's use

After one season of use and three chains, the cog shows only light wear. Abrasion appears on the tips of the teeth, and there's a bit of 'set' where the rollers touch. The drive train turns smoothly and quietly, almost like new (whenever I replace the chain, that is).

This cog works well. I can't complain. What else is there to say?


v1.0 written February 2006

Tom has also written about bolt-on cogs on the FG gallery.
The bolt-on cog article that started it all is here.
Boone have their own site.

Mailing list
Join the list.