22 December 2007

Rotor Stem, headless bolts

Poking around Rotor's website yesterday, I noticed their S1 stem. There's more going on there than just some nice machining, it turns out. The fasteners at the steerer clamp and face plate use dual-threaded fasteners engage each of the mating pieces, drawing them together (think turnbuckle). This apparently (and logically) reduces the compressive forces caused by a bolt head to only the thread (loads of surface area compared to a bolt head) and creates an almost tension-only clamp and light stem (99g in 90mm x 31.8mm). Cool, eh? Somebody's thinking over there.


That said, we're not sure what they're thinking with their upcoming seatpost. The rotation borrows heavily from USE's Sumo design, but the rail clamping bolts obscure the adjustment. There's a cross section to the right as well. It looks like, in order to adjust your saddle angle (the dual-threaded fastener is down hole seen in the left side of the image, right), you'd need to remove the clamping bolts (the red ones). C'mon! move them off-axis (preferably forward), where forces are lower for the vast majority of riding and adjustments will be easier. On second thought, If they're not using the center taper to adjust angle, then there's not much interesting going on there other than an excuse to use their patented fastener, and they could probably take things a bit further. Just our two cents...

rotorcrankusa.com
rotorbike.com
arueda.com

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