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12 Oct 2011

Suspension (1)

Suspension is an important factor on a bike. The most common form is using the right tyre pressure. A tyre that is at a not too high pressure will absorb small road imperfections. The fatter and/or more supple a tyre is, the smoother your ride can be. A light rider deforms his tyres less, so he/she can do with a lower pressure than a heavy person.

The same goes for a shock absorber. A light person needs a different spring, or air pressure in the air shock, than a heavier person. Spring load and damping must be set up correct to keep the wheels on the ground. A wheel that's not on the ground, does not steer or brake. Proper damping is so that 1 bump, translates in to 2 movements of your shock. 1 in and 1 out. Yes, good suspension can very much improve the handling of your bike.

When you take a turn right on a bumpy road, and your rear suspension is not what it should be, the rear end could bounce to the left. A brick road I often follow has a sharp right hand corner. When I take it on my Fuego, with the 28mm rear tyre at 8 bar, at 30kph, the rear suspension keeps the wheel on the ground. On unsuspended wheel could loose grip and bounce of, resulting in serious road rash.

Many velomobiles have a really basic kind of rear shock. They can sort of make up for that with a fat rear tyre. However, it's better to have a proper mtb-style shock. And in my new Evo K, there will be a fully adjustable air shock. Air shocks have something steel springs don't have, progressive suspension. The deeper you push it, the firmer it gets. That means that small imperfections get filtered out nicely, while it won't be too soft to soak up big bumps. Velomobiles most often have 1 rear wheel. When that looses contact, there's no back up. When a front wheel get airborne, there's always a second wheel to keep you in a straight line.

On a two wheeled 'bent, front suspension can be nice too. It's often said that you don't need front suspension with a big front wheel. But I surely felt a difference between my Cruiser (406mm + suspension) and my Pioneer. (559mm no suspension) Even though the Cruiser had 35mm Kojaks and the Pioneer a set of 50mm Kojaks, the C felt more comfortable.
Now the route of a chain can make it difficult to install a front fork with suspension. It varies per model, but it's not easy on an old Pioneer. I did get it to work, and I love it. When you buy the more modern Nazca Gaucho, there is the option to get it with front suspension. (not with USS) It's a version with the suspension built in the head tube that gives slender look and does not conflict with your chain. The travel it has is enough to soak up most bumps. If I where to buy a new Gaucho 26, I'd opt for the most comfortable version. Not that an un-suspended front is harsh, but I really like it plush on my big tourer.

Part 2 about suspension will be about potential power losses and suspension. Yes, you can have rear suspension and ride up a mountain!


  1. Nice read! I'am planning to build my own fwd MBB In your opinion if i could only have one suspension, which one would be more important: the rear or the front?

  2. Thanks.
    On the rear, because that's where your head and spine are.