Building a kid’s bike that doesn’t suck: The Mt. bike frame

Continued from yesterday’s post: Kids’ Bikes: They suck and what you can do about it. It’s possible you may find this a bit too detailed. If that’s the case, visit the flickr stream for quick some ideas and examples.

Pre-upgrade: Reaching for the brakes

For the non-sucky kid’s bike project foundation, I started with Craigslist’s finest: a $65, 21-spd,  24″-wheel Trek MT 220. I like this style of bike because it has a semi-step through frame. I originally tried for a slightly older version, complete with lighter frame and a closer to a true step-through design. Unfortunately, all the samples I ran across were pretty hammered, having been through two or three kids.

The newest frames have their tradeoffs, too. First of all, they are massively overbuilt. They are heavy. And almost all of them are saddled with suspension forks (see how these trends go together: sourcing a suspension fork means the rest of the bike must be up to being ridden high-speed directly into curbs. Again and again.

Suspension is a bad trend for us folks who want to build city-worthy rides. Even if you can find a rigid-fork version of a newer bike, chances are the the bike has been designed as “suspension ready,” which is code for a jacked-up front end.  This extra height makes it impossible to maximize standover clearance and can result in a bike kids find uncomfortable to mount, dismount, and straddle in traffic.

These many requirements guided me toward bikes three to five years old. Newer bikes drew the shock penalty; older bikes were usually trashed or  burdened with paint schemes too dang ugly to pass the daughter test (though I have seen a number of nicely preserved specimens since).

This Trek was in the right place at the right time. The daughter was thrilled with the color, the seller, a first time Craigslister, was thrilled that someone would actually purchase a used bike; I was thrilled to only spend $65.

We got the bike home and immediately changed things. First, a tune up, complete with bearing repacking. Then the trusty bell went on. And the 2.5 lb pot-metal kickstand  (come on Trek, why?) was replaced with a 1lb aluminum Greenfield we had leftover from her old bike.

I’m not a weight weenie, but why make this harder for the kids than necessary? Why bolt on extra weight, like the stupid derailleur protectors. I think the logic goes like this:  manufacturers sell the bike as a disposable toy, so the kids treat it as such and drop the bike on the drivetrain side. A simple 1lb derailleur protector solves the abuse problem and keeps Shimano’s flawless shifting reputation intact.

the dreaded derailleur protector

Since our daughter treats her bike as a bike I elected to just explain how it’s important to use the kickstand and keep the derailleur side of the bike up. I painted the thing pink and said if she could go a couple weeks without losing the paint, I’d remove the offending hunk of steel and lighten up her bike a bit. Two weeks later I removed it, paint intact, (In fact, the only scratches are because I knocked the bike over in the garage) and the bike is 400 grams lighter (no, I’m not exaggerating. It really weighs that much).

All this made bike  better, but still not perfect. Longer rides hurt her hands, wrists and back, she didn’t like the “buzzing” of the knobby tires, and the season’s increasingly wet weather forced her back on the Xtracycle (at least if she wanted to avoid a mud stripe up her back).

Luckily we can solve all of this in future posts (Tires, if you are curious, are next).

-Tim