August 11, 2011

Downhill Introspection

Chris emailed me with an interesting question about my old 29er downhill bike (if you don’t remember it, you can read about it here):

How would I do a bike today for DH and 29″ wheels differently than I did 4 years ago? Given how excited I was about the old one, I was surprised how much it seems totally obsolete to me now:

Hi Chris –

Some stuff I’d do differently:

-Design for 140-160mm fork (the current one is built for a 180, and it’s WAY too much fork for me), with a tapered steerer (so 44ID head tube).

-ISCG mount (shoulda done that on mine, but was planning to run a front derailleur).

-Shorter chainstays (probably in the 43cm range?) for more manualing/wheelie fun (currently they’re 45cm).

-6″ or 6.5″ rear travel rather than 7″ – once again, too much travel for the way I ride, especially with the big wheels.

-Supertherm throughout (mine is only partially Supertherm, as True Temper did not make it in 29er-friendly configurations back then) to save weight and add some strength.

-31.6 or 30.9 seatpost for Joplin/other height adjust posts. Mine is 27.2, and the GravityDropper is a crappy post, IMO.

-Slacker front end (mine is 69 degrees, I’d probably go 67 or 68, especially if using the Fox34 140 Talas so I could crank it down if/when I wanted it to steer quicker).

-1″/25.4 main pivot axle. Mine is 24mm and it’s annoying to do the preload. With the 25.4 I could just drive some 1″ star nuts into the (hollow) axle and then use 1″ headset end caps instead – lighter and stiffer, and easier to work on.

-135 or 142 maxle, rather than non-threaded 150×12. Lighter, just as stiff, easier to deal with when installing the rear wheel.

That’s probably about it, but as you can see, it’s a pretty extensive list! If I were doing a light-duty DH setup, I’d probably just use a Ventana rear end modified for 6″ travel (I just use a longer stroke shock and longer rocker with a normal rear end) and build around a 140 Talas fork. That would be the ultimate freeride setup – 68 degree HTA that goes to 69.5 with the talas cranked down, tapered, ISCG or even Hammerschmidt…