19 August 2008

bikefix Exclusive Review: Shimano Centerlock adapter

It's hard to argue with the logic with Shimano's Centerlock disc brake rotor mounting system. An internally splined rotor is mounted to a matching hub and held in place with what is essentially a modified cassette lockring- a tool for which most riders own already. The XT Centerlock rotor & lockring weigh the same as an Avid rotor and its 6 mounting bolts and the hubs are certainly lighter. Furthermore, it's less likely to warp a rotor through improper installation and the likelihood of the skinned knuckles that occur when the Torx wrench slips out of tiny pan head bolts is all but eliminated.

The danger, though, with new standards (regardless of their technical merit) is that they tend to leave all sorts of legacy equipment behind. Such was the case when I picked up a set of Shimano's XTR wheels and rotors recently. The set came with some beautiful XTR rotors, but unfortunately both were in the 160mm size. Because I feel that a bigger front rotor helps to balance braking power and feel, I was in the position of either buying a new Centerlock rotor (XTRs run $60) and leaving two perfectly good 6-bolt rotors on the pegboard or finding some sort of adapter to make those rotors work. After looking at options from DT, Dimension and Shimano, I opted for Shimano's elegantly named ESMRTAD10.

Not cheap at $27.5o, the kit consists of a splined base with 6 bolt-simulating posts, a serrated locking plate, a retaining ring and lockring (handily marked with fixing torque). While no doubt designed solely for Shimano's rotors, my 180mm Formula 6-bolt rotor fit very snugly on the base plate's posts (thanks to happy accident or exacting tolerances). The locking plate sits over that and is kept in place by the locking ring (which only weighs 7.2μg, so don't bother leaving it off). This tidy little subassembly slides right on to the Shimano hub and is held in place by the lockring, torqued with the precisely envisioned weight of 40 sticks of butter sitting on the end of a yardstick.

That's it. Three months later, I've had no problems. No loosening, no noises, nothing. While not as light or clean as a pure Centerlock system, it's keeping some good parts in service. The adapter kit is clearly well thought ought- I'd be tempted to call it overdesigned, but there's probably no such a thing as an overdesigned brake. As an added bonus, the assembly comes off readily to reduce the likelihood of damage while packed for travel. The price is a bit steep, but it works well and (unlike Dimension's adapter) retains the benefits of the Centerlock system.



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