Some Square Taper Bottom Brackets

Second in a series on bottom brackets. Numero uno is here.

The newest (2012) Long Haul Trucker complete bikes come with the Shimano UN55 square taper bottom bracket which is an improvement over the UN-P.O.S. used in earlier years, but when asked what I might upgrade on a stock Long Haul Trucker I am likely to recommend a new bottom bracket. Don’t get me wrong, the bottom bracket that comes standard on the stock LHT is perfectly adequate. But there are bottom brackets that will last longer.

With bottom brackets, one gets what one pays for. In this case more money buys better bearing seals, higher quality bearings made to stricter tolerances, and better materials throughout.

Phil Wood Company designs, manufactures and assembles precision bike parts in San Jose, CA. USA. Their bottom bracket uses two adjustable cups to hold the bearings and spindle in place which makes it possible to achieve the perfect chain line, since the bottom bracket can be positioned within a 5 mm band of “normal” centered position. The cartridge bearings are plainly visible when the unit is installed, which might make one wonder about the durability when used in extreme conditions, but Phil Wood Co. uses “seals which are as good or better than those found in the highest quality submersible motor and pump bearings”. I have only seen one Phil Wood bottom bracket that needed servicing though, and even that was straightforward….the unit can be sent back to the company for new bearings at a reasonable cost.

Phil Wood cartridge bottom bracket

The left and right cups use an interference fit with the bottom bracket and require the use of the Phil Wood bottom bracket tool

SKF is a German company (Correction: Thomas K. correctly points out that SKF headquarters are in Gothenburg, Sweden) which has been a leader in bearing technology since 1907 and today is the largest bearing company in the world. Their approach to bottom bracket design strives to incorporate the best of old and modern technology. Rather than using cartridge bearings pressed onto the spindle and into the bottom bracket cartridge they use bearings which are received by races which are part of the spindle and the shell. Custom seals are used to keep contaminants away from the assembly. This way they can use roller bearings on the drive side and over-sized bearings on the non-drive side increasing durability and strength. This design has some appeal to the retro-grouchy Bike Hermit, and SKF is proud of it too….they offer a 10 year or 65,000 mile warranty (just be sure to keep track of your miles) 😉

SKF bottom bracket. The little bit of bling afforded by the red cup is not undesirable.

The mechanical seal designed to keep the bearings cozy and happy in the most inclement weather