June 20, 2009

A few random shots of Guy’s bike, thoughts on s-bend chainstays

I recently received some very nice new True Temper s-bend 29er chainstays (at no charge, no less – thanks guys) to mess around with. Here’s a shot of the new stay in the fixture with the single bend (HOX5CS) 29er chainstay on the left for perspective.


-The 30/16 (oval) profile is perfect. Love it. True Temper’s other mountain chainstays tend to be 26 or 27 by 18mm. 2mm of extra space on each side is a godsend when trying to cram a big tire into a short-chainstay frame.

-They weigh a lot less than spec. Both of mine were 158g. That’s almost 20g lighter than the spec sheet indicates, and a good 15g lighter than the HOX5CS (actual weight) that I’ve used a lot of in the past. A little sketchy.

-I’m sort of hesitant to use them for a bike that will see serious offroad use – the stay is, after all, lighter than the spec listing for the _OX platinum_ (a material with a higher yield strength) mountain bike chainstay, and the wall thickness is thinner than the OX plat models, despite the stay being made of somewhat less strong material. Was there a reason that the TT guys departed from the .81/.66 butting on the HOX5CS? I’m not sure, but I do know that these won’t be appropriate for big or aggressive riders – which, in my experience, constitutes a big chunk of the 29er market (yeah, you guys and gals are studs, admit it).

-The bends aren’t ideal for clearing decent sized tires. Some combination of an extra 2-3 degrees of bend at the forward (positive) bend and 2-3 degrees less at the negative bend would be better. As it stands, these are very hard to use for anything but frames intended for fairly small (2.0″ and smaller) tires. The locations of the bends, on the plus side, are perfect.

In any case, I probably can’t use these for much as they stand, except for smaller riders who aren’t concerned with tire clearance too much, or for bikes that aren’t intended for really rough offroad use. They are, in my mind, essentially cyclocross chainstays with a lot of bend. I’d love to see some tweaks to the next version to make them a bit more mountain bike appropriate and versatile.

Luckily, they’re perfect for Guy’s frame – he wants a fast singlespeed street/town bike with mountain bike handlebars, clearance for 2.1s for the occasional foray onto dirt, and light weight. Perfect! Here’s a shot of the BB shell/DT/ST/CS cluster.