Three Speed MTB
Contents
The Good Choice
Bontrager offers a hub identical to the $35 hub described below. It cost $79.99. 430g. P/N #271412.
It is different in two ways:
- Drilled for 32 spokes
- Quick release
This solves many of the problems with the $35 for a bit more money. In retrospect, I should have used this hub.
The $35 Hub
This hub is offered by several companies at various price points. It is a essentially a Formula BX-2210 BMX Cassette Hub with 135mm spacing and an upgrade to cartridge bearings. It can also be found as a Novatec (Joy) D256SBT. Other companies branding it under their own name are Woodman, Planet-X (On-One), IRO, and Bontrager. Many others may exist, but the cheapest one I was able to find was the Nashbar NF-SSHR. Cost $34.95. That is CRAZY cheap.
One Problem. The hub is drilled for 36 spokes. This is bad. 32 spokes is standard, so this makes parts inventory difficult. It also drives the weight up.
The Nashbar hub includes a sprocket which some of the other companies neglect to include.
Internal parts
Two bearings in the cassette body. Quality.
Converting to Quick Release
The hub comes set up with a bolt-on axle. Pretty lame by modern standards. It needs to be converted to quick release and do on a serious diet. The solid axle is a literal boat anchor.
A generic quick release axle for this hub would be 146mm wide with a 10X1mm thread. Since this is a special axle type, a replacement must be sourced from a similar hub spare parts list.
Since Bontrager is now using this hub in both itterations, #250795 Bolt-on and #271412 Quick Release, we can source parts through the local Trek dealer. Quick release axles for it, #SP-271397-TRE, can be ordered for $20.
The Bontrager hub retails for $79.99. It's a good price, but we can make that cheaper. Our total hub cost with new axle is now $54.95. Nice.
Gearing The Cassette
The cassette lockring is a standard ISO 1.375x24T right hand thread lockring. Same as old school bottom brackets. I replaced the cheapo one with a nice old Suntour version that I had in stock.
A 15-18-21, nine speed spaced, 3 speed cassette.
Four Speed?
A Uniglide threaded cog, if you can find one (8spd), at the end of the cassette can be used instead of the lockring to make this into a four speed cassette.
Since Uniglide parts are almost extinct, another option still exists. Surly makes Track Cogs. They are threaded at ISO 1.375x24T and come in two widths, 3/32" and 1/8". They are available in teeth options from 13 to 22.
Chainline
With the cassette described above and a small spacer on the back side of the cassette, the chainline for this rear end comes to 48.5mm. Quite narrow, but possible using some extremly short square taper bb's.
Zero Dish?
The wheelbuilding info on this hub is as follows:
- Diameter of Hub at spoke hole circle: 58mm
- Right (drive side) center of hub to flange: 34mm
- Left(brake side) center of hub to flange 38mm
- Diameter of individual spoke holes: 2mm
So, the dish is off by 4mm and spoke length works out to be 262mm (left) and 261mm (right) when 3 crossing a Mavic XM321 rim.
This is fine. At least the spaceing erred on giving a wider hub flange spacing, 72mm. That is almost 6mm wider than my Hadley single speed hub (66.4mm).
This is going to make quite the bomber wheel.
