Wednesday, December 01, 2010

John's DH bike - almost there

With apologies to Tropic Thunder, this is a case when going full retard is absolutely justified.

In other words, this is a bike intended for doing things that are basically stupid.



-29" wheels, 6" travel, room for 2.5s.
-Supertherm top/downtubes and a big 44mm head tube for a tapered steerer.
-Nice 44.5cm chainstays/112cm wheelbase.
-Mounts for ISCG/Hammerschmidt and a direct mount front derailleur if needed.
-68 degree HTA
-29.5" standover
-A nice solid 8 pounds, give or take, with the shock (this thing is deliberately overbuilt, it's certainly possible to make a "freeride" or long-travel XC bike much lighter, but we wanted John to be able to fall off cliffs).

She's almost done, I just have to do some cable stops and final checks, then off to the powdercoater in a few days.

The second pic, btw, is of the direct mount FD mount before I brazed it in. The seat tube here is so offset that I have to make the mount in 2 pieces, then braze it all together (and to the frame) with brass. The direct mount jig is just an old piece of aluminum plate with a few holes drilled (and some offset machined in at the bottom bracket). As you can see, it's been used and abused - I'm sure this was a piece of scrap I picked up somewhere, though I don't remember for sure.

12 comments:

Jonathan Stanley said...

Nice. Look forward to more (and higher resolution) photos (on Flickr?)...

On the subject of stupid bikes though... did an email from me sent back on 10th Nov. ever get to you, or did Gmail's overzealous spam filter eat it? :(

Walt said...

Jonathan -

My computer (10 years old) isn't so good with high-res photos, unfortunately.

I did not receive an email from you, as far as I can tell. Maybe try calling me?

-Walt

MatB said...

What fork you going to use with enough travel to balance that beast out?

Walt said...

For now, it will run a 140mm (5.5") Reba. In the future, I'm guessing a reduced-travel (ie 6-6.5") Dorado is a strong possibility.

WB makes a 150mm 29er fork, but I'm not a huge fan of it, personally.

MatB said...

Wow. I think you may have to measure that bike like a horse. How many hands tall is it?

Walt said...

Well, the standover is 29.5", so that's, let's see - about 7.5 hands, right?

Bars are level with the saddle (at XC height) with a stubby stem and low-rise bar, so the tallness isn't *too* bad. One of the nice things about the 44mm head tube is that the upper headset stack height is like 3 or 4mm - so it gives you a cm less height in the front end if you need it.

CJB said...

I was glancing thru here and ran across this. Nice build Walt. I'd love to see some more pics. These numbers seem close to what we did with our 150mm FS bikes. How high is the BB? What length rockers?
-CJB

Walt said...

Hey Cody -

Yeah, I think it's very close to what you guys did, but with a different pivot location (to allow a front derailleur) and maybe a bit more standover due to the 2-piece toptube.

BB height with no rider is a little over 14" - with really huge DH (ie Dissents) tires it is probably 14.25"?

John Palmer said...

Even though it's California, my favorite rides are snowed in. So I may just hang it in the living room and drool. No, wait, I know a ride... Montara Mountain in Pacifica. :-)
Thanks Walt. I can hardly wait.

kiri said...

This bike looks sweet. Too bad I won't be able to steal it. We might be related but I need a pony compared to this horse of a bike. As to you building a bike so that my dad can ride off cliffs... I'll get back to you on that. I kinda like having my old man around.

PS Dad, while your bike can go off cliffs, I wouldn't recommend you go off cliffs.

John said...

OK. I'll just jump off and pitch the bike over the cliff w/o me. :-) What about small cliffs? I have life insurance a while longer.

Jonathan Stanley said...

Hi Walt. Thanks for your reply. However due to timezones (I'm in Hong Kong) and the fact I just really try to avoid the phone when I can, I've sent you another email. Might be worth checking your Gmail spam bin... :)