New frame materials and progression in bike design have created more ‘standards’ across the bike industry than you can easily keep track of. Take a look at your bike and it’s easy to see where there are many changes in what is meant to be a standard. From the front end of your bike to the back, there are different hub axle diameters, headset types and bearing sizes, handlebar diameters, steerer tube diametres, seat tube diametres, bottom bracket widths, thread types and shell sizes, disc brake mounts and back to hub widths and axle types. And that’s all before wheel sizes.
In building up the Bianchi Methanol 29 Hardtail bikes for the Subaru-MarathonMTB.com Team that this site co-sponsors, we came across a small hiccup with the parts that we chose to use. Bianchi use a Press Fit 30 bottom bracket standard on their carbon fibre mountain bike range, and the Team favours a Shimano drivetrain for greater global parts supply and parts interchangeability between Team members bikes at races. The problem here is that Shimano don’t currently support the BB30 standard.
This is by no means a unique problem nor a new one. The BB30 standard has been around for well over a decade and there are many ways to use a crankset that uses a smaller diametre axle with a bottom bracket shell that can accommodate a thicker axle. Each solution out there has detractors and enthusiasts.
One option that came up was that made by Praxis Works. These units aren’t a shim to fill the area between a Shimano crank spindle and a bearing with a 30mm internal diametre – they actually use the construction of the unit to expand into the hub shell and run the bearings more outboard than the typical 73mm shells on the Bianchi Methanol 29 hard tail frames would allow.
Fitting is quite straight forward.
1. Use a fibre paste on the frames bottom bracket shell if it is carbon-fibre. Otherwise use an appropriate grease.
2. The unit is still a press fit. Push in the main part of the unit (the left side and shell) from the non-drive side. As this is a PF30 frame, the extra sleeve stays on the unit.
3. Use a headset press to push it in straight.
4. Press the unit in until the o-ring is almost under pressure
5. Ensuring there is enough grease on the threads of the unit, start to wind the drive side cup in. Use two Hollowtech II tools to ensure a snug fit.
6. The compressible o-ring will become quite compressed – and it allows for slight variations in BB shell width. You can see excess fibre paste has spilt out. Make sure you wipe away the excess.
7. Fit your cranks up, and you’re ready to go.
Three of these units were first fitted to Bianchi Team bikes in September 2012 before the Crocodile Trophy, and used with much success at that race. Those three units are still going strongly, and so the Praxis Works units have continued to be used on other Methanol 29 HT frames. However, the new Methanol 29 FS frames do use a PF30 bottom bracket shell, but with an internal lip. As these bikes are being built right now, it is a case of using a PF30 bottom bracket and Wheels Manufacturing adaptors to fill the space. Time will tell which one works better for our Team riders.