Sunday, December 26, 2010

Elephant Kid Bike

I've been posting a bunch of nit picky bits and pieces about this bike over the last couple weeks, but I wanted to do an all-up post for people searching for this bike to get the full story.

The goal with this bike was to produce a good-enough, low-cost performant kid bike in about 3 weeks. If you've looked around for a reasonable-weight with ok components in a kid bike, then you know the bar here is extremely low.

Glen pitched the idea to me around the beginning of December, so we were in a bit of a rush to get everything together so the frame could make it to the powder coat in time. Most of the steps, from building the wheels and chopping up an old frameset and building up the frame are tagged with the maddie xmass bike label.

To keep the out-of-pocket cash output as low as we could and to hit our aggressive xmass eve date, I scrounged the parts, we used a donor frame, and Glen didn't do any finish work. I think the result is incredible. Mind you, Glen has a ton of experience -- he cut his teeth at Bontrager's back in the 80s, he built bikes for Serrotta, and he's done a bunch of other bike stuff -- so "not doing clean up work" wasn't exactly a huge risk.

Click for big to read Glen's card.
Officially, the deal was that I traded a set of old compact Ritchey cranks (the bitchin' 94/58 Sugino ones) for the frameset. Of course I ended up spending too much on parts. We had to powdercoat it. So it ended up costing a few hundred dollars. Which is a bargain anyway you slice it.
The tubing is as follows:
  • Top tube: Ishiwata EX (from RB-1 donor frame)
  • Seat tube: Ishiwata EX (from RB-1)
  • Downtube stays: new 4130
  • Chain stays: adapted from a 90's Rockhopper
  • Seat stays: these are the seat stays from RB-1. Glen wishbone design
  • Head tube/bottom bracket shell: new
  • Fork steerer: Reynolds 531 NOS
  • Fork blades: Reynolds 703 NOS
  • Kickstand plate: off old Gitane
The donor frame was an 89 Bridgestone RB-1. This was not a pristine frame: one of the rear drop outs on the frame had been replaced and the head tube was a bit stretched. But it was still ridable. And given our goals, it made a great donor frame. The tubes on the Bridgestone were Ishiwata EX, which were a strange butted profile ranging from .7 mm to 1 mm thick.

The rear chainstay came from a 90's Rockhopper. The beauty of using the Rockhopper rear chainstay was that it was pre-bent in a way that worked for good tire clearance and small rings.

Parts:
  • Bars: steel risers from an old Gitane
  • Stem: custom Glen-made
  • Shifters: Suntour XC Pro 7 speed
  • Brake levers: Dia Comp, bent to match contour of bars
  • Headset: Origin8 1" threadless
  • Saddle: Velo kid saddle
  • Post: Origin8
  • Crank set: Origin 8 with 46/34. 155mm
  • Bottom bracket: Origin8 107. (Tread/Q: 155)
  • Pedals: MKS sneaker pedals
  • Wheels: Velocity Aeroheat 24" (507 mm), laced to Mavic 550 hubs. Straight-gauge spokes
  • Tires: Kenda semislicks 24x1.75"
  • Brakes: Tektro mini v
  • Front derailleur: Shimano 600
  • Rear derailluer: Dura Ace 7401 7-speed
  • Freewheel: Sunrace 7 speed, 14-28
Geometry
I made a point to keep my opinions about geometry to myself. I have a dim sense of what I like and I over-emphasize the front end of the bike, but I just don't really understand the end-to-end interaction of all geometry stuff, especially for a kid's bike.

Glen draws stuff out to scale on a big wall-mounted drafting board thing. As he builds, he can then hold up finished bits to the drawing and check progress.

I get into specifics of angles and the theory and the math. Glen nods along as I chatter about this stuff, but when pressed for his approach to design, he talks of balance, weight distribution, toe clip overlap, reach, stability, and other basic traits he wants in a good bike. These traits are then put up against fixed requirements like wheel size and stand-over height. A design emerges.

In this case, Maddie's low stand-over height surprised him. She seems tall because she's slim and always wears high-water pants. To make the stand-over work, he went with the "quadangle" design. This comes from the BMX world apparently. Specifically, it's referred to as "SE quadangle racing" bmx frame design. To provide a lower stand-over, the top tube is attached to the bottom of the headtube. Then stays are used for the down tube, attached at the top of the head tube.

Building the frame
I tried to be at Glen's shop as much as I could as he put the frame together. Watching him work is fascinating to me. I expect to see a lot of precise measuring and exact perfectionist OCD-type work. But Glen's way is very organic. Without getting too carried away with the metaphor here, watching Glen work reminds me of watching my buddy, Don, a pianist, improvize through a standard jazz tune. In both cases, there's a well-understood foundation on which to build. In both cases, these guys have spent hundreds and hundreds of hours in solitary practice honing and perfecting their craft. Watching Glen put the bike together now, is really watching someone who is enjoying the process -- and with each task, makes judgements and adjustments based on years of experience and practice.

Aside from two of the bottom bracket joints, which are TIG'd, the joints on the frame are mainly fillet brazed. Glen really didn't do any clean up work at all. The powder coater probably did a bead blast to get the old paint and some gunk off the frame. It's hard to appreciate the cleanliness of the fillet brazes from the pictures.

The fork crown and the rear wishbone seat stay are both custom made by Glen. There's a sleeve at the seat collar.

The parts
The interesting bits are the short cranks, shifting, stem, brakes, and wheels.

Origin 8 actually makes cranks as short as 145mm. We went with 155 mm. It's a standard 3-piece, 110 BCD, forged aluminum crank. It takes a square taper bottom bracket.

We spent a bunch of time hemming and hawing over the shifting. We wanted indexing for the rear derailleur. I'm pretty ok with sloppy indexing. Glen is not. He spent part of an evening trying a bunch of different shifters with a bunch of different derailluers to find a good 7-speed solution. In the end the old Dura Ace rear derailleur, paired with the Suntour XC pro shifter was the winner. By wrapping the derailleur cable around the "wrong" side of the pinch bolt on the derailleur, perfect indexing was achieved.

The front shifting is same vintage Shimano 600. The tube Glen used for the seat tube had a water bottle boss still on it. So he used it for the cable pulley for the front derailleur -- so he could run shifting cables along the top of the top tube.

The stem is a custom jobber. He made it from a steel tandem stoker stem.

Brakes are mini v's. You can run mini-v's with standard brake levers. The Diacomp brake levers are a nice finish and he wanted them so he could bend the levers to match the contour of the bars. The rear brake housing braze-ons that run along the bottom of the top tube were on the original tube. They were for the brake cable that ran across the top of the top tube on the RB-1.

The wheels are nice.

The Mavic hubs are just super fine hubs. They're smooth, they polish nicely, and they should last Maddie a really long time.

There are two 24" wheel standards still readily available today: the 507 mm size, which is often referred to as "mountain" or "bmx" 24, and the 520 mm size which are typically used on small road bikes, like Terry, and were once used a lot on time trial bikes. Since you can only get 520 mm tires in 1" super narrow sizes, we decided to go with the 507 mm size. There are not as many great road-ish tires in 507 mm, but there are a few out there. And there's lots of knobby/fat 507 sizes. Maddie's bike could take up to about 2.0" tires.

The rims are Velocity Aeroheat, which are great, light, easy-as-cake-to-build rims. And they're silver and pretty. Maddie helped me build the wheels.

Other kid bikes
Glen is always interested in building more bikes. He's talking about figuring out a good quality build kit for kid's bikes like this. His idea is that there are probably a lot of pretty good old steel frames hanging in garages of bikey guys who have kids. This method, where he chops up a bike with decent steel to make a kid bike, is a cool way to get more mileage out of your old rig. I know lots of people who have old "classics" that they hang on to but never ride. Think of all the great potential kid bikes out there.

Really, having the frame to chop up doesn't really save much money. Great tubing for a kids bike could be had for around $100, and in fact, cutting a frame up and cleaning up the tubes isn't a huge time saver either. The process is fun though and in our case, it did save time since we didn't have to order tubing and I was able to help with some of the running around/parts gathering. Plus, Glen really enjoyed the irony of chopping up an RB-1, in my size, for Maddie. We discussed it, and it turns out that this is ironic. I'm not misusing the term here.

If you want one, contact Glen and see where the process takes you.

8 comments:

Dan O said...

Very cool bike. Not exactly something you see every day.

Nate said...

Well told.

Could this bike make an appearance at a bike hang?

Fred Blasdel said...

I think you accidentally put 520 instead of 507 in a bunch of places in the paragraph about the wheel size…

At what point do you think she's going to outgrow it, and would she graduate to 559 or 622?

Rachel said...

Fantastic post!

And if the bike's coming to a hang, you must announce it because I want to be there!

John Speare said...

I'll let you guys know if it makes it to a hang. I can't load it on the cycle truck yet -- I need to let Maddie make the first scratch.

Fred: good catch! Fixed it. Thanks.

BiketoWork Barb said...

Hey, this post got tweeted out by an account named @totcycle from Seattle (www.totcycle.com). The Twitter post read:

Cycling Spokane: Elephant Kid Bike http://bit.ly/gKSsNB Now this is one mighty fine kid's bike. Nice work!

Congrats! :D

@BarbChamberlain
@womenbikeblogs

The King Asshat said...

I've been lurking for a while, I just moved to Spokane, and this blog popped up when I typed in "cycling blog spokane". Anywho, this bike is completely awesome, I especially like the fact that you cut up an old bridgstone for the main tubing. Hope to see you at a Jones Radiator hang sooner or later.

-jacob

Allen brownie said...
This comment has been removed by the author.