September 7, 2014

A big one

Let’s be honest – 95% (or more) of the folks who come to me for a custom bike are just really picky about what they ride. They could fit on a stock frame but for whatever reason they can’t find exactly what they want, or they think it’s really cool to have something handbuilt with exactly the geometry and components they want, or maybe they (inexplicably) think having a Waltworks will make them cool. Lots of reasons, all good ones, but realistically, most people could make a stock frame work if they had to.

Not Jan. Why? Well, he’s not quite into Andre the Giant territory but he’s close. 7 feet and almost 400 pounds means he can’t fit on, let alone safely ride anything off the shelf. Plus, he wants to go *mountain biking*, not just toodle around on the street. Lucky for him I’ve done bikes for folks his size before.

Leaves still green for another few weeks.

To make it happen, the usual uses for various stock frame tubing get thrown out the window. To whit:
-The seat tube is an upside-down (thick portion at the bottom) 1.6/.9 x 34.9 True Temper tube intended for a 31.6 post, with an additional plug of .065×1.375″ (sorry, it’s bike tubing vs. aircraft tubing and metric mixed with SAE as usual) welded into the top for the post.
-Downtube is .049×1.75″. It’s like a softball bat!
-A heat-treated 1/7/1 x 34.9 “downtube” is the toptube.
-Chainstays are .049×7/8″ 4130.
-Seatstays are .035×3/4″ 4130. To put that into perspective, those would be pretty beefy *chainstays* for a normal rider.
-NOS 12mm downhill dropouts (Jan will run a 135×12 rear hub, since we needed the strongest thing we could find and 36h drilling – that means an old-school Hadley DH hub) that are made from full-on 1/4″ 1020 steel plate. Wow.
-The bike will run a WB tandem suspension fork with an uncut steerer and a 3″ riser bar (as well as a riser stem) to get the bars high enough (Jan’s saddle height – 90cm)!

BB cluster of doom. Had to crank up to 150 amps for some of this!

The final weight of the frame, because I know everyone will ask, is about 9 pounds. I’m expecting the complete bike to end up in the high 30# range.

Geometry, for those who are interested:
-70 degree HTA and 90mm trail. 29″ wheels.
-73cm effective toptube and 796mm front center.
-50cm chainstays and 34cm BB height (Jan will run 185mm cranks)
-92cm standover!
-For a 31.6 post not because it’s going to be a dropper, but because it needs to be big and strong (Thomson).

Some of you may remember my infamous Yao Ming Gunnar rant.  So:
-We were not on an infinite budget and custom headsets, 36″ compatible suspension forks, or even custom cranks were out. So some things were done to enable compatibility with relatively standard (ie Surly Mr. Whirly 185mm cranks, 135×12 DH hub, 29″ wheels and compatible suspension fork appropriate for Jan, etc) components. Could Jan fit a 36er? For sure. Would it be the best option for him to go mountain biking? Probably not given that he wants suspension.
-Frame weight is under the “10 pounds or it’s underbuilt!” claim I made back then. But it’s close to 10, and I’m not sure what could be much beefier and have any useful effect on the ride. Time will tell!