Cargo bike foolishness

June 26, 2011

Turns out, it is a bad idea to run fat tires on skinny rims. It’s not just weird handling at low inflation — because the tire is almost perpendicular to the rim wall, the full tension in the tire casing (proportional to the product of the pressure and tire diameter) is applied to the rim wall. This can cause cracks.

I’ve been off my cargo bike for two weeks now, waiting on parts and wheel build. I’m upgrading to the finest internally geared hub, a 14-speed Rohloff. I broke my SRAM hub last year, and this year, I’ve unscrewed the new Shimano rear hub several times despite the anti-rotation washers. It should be nice.

I also got a bee in my bonnet to finally build a wheel, since I had a spare rim (old SRAM wheel) and a very low-priced dynamo hub. I followed the Sheldon Brown instructions, but unfortunately, got the spoke length wrong once (bought spokes for a 700c Rhyno Lite, not the 26″ Rhyno Lite), twice (reusing spokes that measured out long enough for a likely looking 26″ Rhyno Lite version that turned out to be the wrong one), three times (either I measure spokes incorrectly, or else I was handed replacement spokes from the wrong bin by accident). However, I did actually get the wheel built before realizing that the spokes were too short, and it wasn’t that bad, and I’ll bet it would be even easier to do with spokes that weren’t 3-4mm too short. Once I get that sorted out, and the wheel built right, I’ll see about buying another rim and building a wheel around the 8-speed hub; on a non-cargo bike, for a smaller person, it should work very well.

One interesting thing about this little exercise, has been discovering just how nice I had made my cargo bike over time, and how useful it really is. Carrying stuff on your back gets old pretty quickly, especially when your back is 51 years old. A front basket works ok, but it keeps making the bike it’s on fall over. Rear grocery-bag panniers are not that bad, but they have to be tied down, and stuff can bounce out, and they’re not that big (one bag per pannier, period; an XtraCycle can take 2 on each side easily, 3 with a little care, plus whatever can be lashed to the deck). And of course the big bike has a nice worn-in saddle, fenders, and lights.

The tandem has panniers and a basket, but no fenders, no lights, a crappy saddle, and handlebars that need to be a little higher up or further back. The Capo is a sweet little bike, with a nice saddle and the best lights (it is the lights-experiment bike), but has no baskets or panniers (cargo goes on my back), no fenders, and tires that are quite skinny, and thus much more vulnerable to cracks in the road and potholes. In theory, the tandem is a better bike for carrying people, but passengers prefer the xtracycle — it’s easier to get on and off, and hey, no pedaling!

The 3-speed has fenders and a nice saddle, but no cargo capacity (not yet), antique brakes, and the light is out of order. The antique 3-speed hub sometimes pops out of gear, too.

So. Given this little experience, I even more enthusiastically recommend purchase of a cargo bike, complete with lights, fenders, upright handle bars, fat tires, and a good saddle. Sun now sells their new cargo bike, and it is quite affordable, and getting decent reviews from people who have tried it, especially given the price. Ordinary bikes don’t come close to being as useful as a cargo bike.

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