Thursday, 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 150x12. 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...


mike said...

does the DH bike in the photo still exist? slightly off topic... any thoughts on the valmont bike park? i have watched the videos and convinced myself i could ride the XL line.

Neve_r_est said...

So for long travel fork options we have Manitou Dorado(175mm), Fox(140), White Bros(maybe being produced but crappy damping), and some sort of RockShox 140 thing coming out, am I missing any? Fox the best option you think? Thinking more long travel all mountain/freeride than DH. Not enough of an impact sport fan for true DH....

Walt said...

Mike -

It still exists, but in pieces. I never rode it again after crashing at Sol Vista (when the craptacular WB fork bottomed out unexpectedly) and spraining my wrist.

Neverest -

I think the Fox34/140 is probably the best option right now. WB sucks, the Dorado is overkill. And the Rockshox is kinda flexy, IMO (32mm stanchions?). Don't even get me started on the Marzocchi, it's like riding a rigid fork.

So not a ton of options, but more than there were a few years ago.