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Speedometer Installation Tips

A bicycle speedometer is most useful, not as a speedometer ("I know I was doing at least 25 when I hit the tree, because I was trying to read my speedometer at the time..."), but as an odometer. Every bicycle guidebook gives riding instructions in terms of the distance you've traveled ("At exactly 1.67 miles, watch for a faint singletrack leading up a small gully to your right...") If you don't have a speedometer, you won't do well at exploring new trail systems.

Because speedometers are easily broken off in a crash (and even more easily broken off when the bike is placed upside-down to remove a flat tire), may I suggest you use riser handlebars (which bend upward at the ends) or bar ends. Angled slightly upward, bar ends form a protective pocket for the speedometer.

Look for a speedometer with a stout connector cord, like this one. Flimsy wires will tear off at the first touch of a twig -- which happens very quickly if you ride narrow alpine singletrack.

To keep the wire from being yanked out of the mounting, use an extra cable tie to secure it to the handlebar a short distance from the mounting.

Helpful hint: I'd broken several speedometers and mounts when a fellow race team member gave me this advice. In retrospect, it seems blindingly obvious, but it was a revelation at the time. Barely tighten the speedometer mounting hardware -- just enough tightness that it stays in place as you ride. That way, when you crash, the speedometer will twist on the handlebar, rather than breaking the mounting hardware. And you can quickly rotate the speedometer before flipping the bike over to fix a flat tire -- so the lens won't get scratched in the dirt and rocks.
For a front-wheel mount, route your wire down the rear side of the shock, slightly towards the outside. This puts the wire where it's less likely to snag a branch. You may think it'll be safer slightly towards the inside, but remember that the wire will bow out when the shock compresses. As the wire bends out into a semicircle, the air current from the rapidly spinning front wheel will suck that floppy wire into the wheel!

Secure the wire with cable ties above and below any areas that bend or flex. Be sure you're leaving enough laxity between the handlebar and front fork, so the front wheel can turn fully in both directions without tightening the wire.

Most speedometers are designed for the front wheel. Mount the detecting wand, facing downward, on the inside rear corner of the fork, about 6 inches above the wheel hub. If your magnet attaches onto two adjacent spokes, you'll need to put it where two spokes are the right distance apart. This will depend on your spoke lacing pattern (radial vs. 3-cross vs. 4-cross).

Usually, the magnet should pass the detector with about 1/4 inch of the detector's tip on the other side of the magnet.

If you have disc brakes, mount the detector on the opposite side.

But if you have a Lefty shock, as shown here, you may need to get inventive. (Or, you'll need a rear wheel mounting kit, which has a longer cable.)

A rear-wheel mount must usually be purchased separately. Not all speedometers have these, and the mounts are usually NOT interchangeable between brands. A rear-wheel mounting kit is simply a longer cable. Attach the clamp on the side opposite the chain, wherever it seems most "out of the way." Put it far enough back that it's out of the way of flying mud and close to the spokes. Mount it facing upward, so it's not likely to catch a stick or rock that's been bounced up by the front tire.
If you have a flimsy wire, you can give it some protection in critical areas by making a twist housing. For example, you might use this to cover the wire where it passes by the front shock.

Get a thick-walled drinking straw. With small thin-tipped scissors, cut a spiral down the length of the straw.

Slide the wire into the cut at the top of the straw. Now twist the straw onto the wire. Clamp it above and below the vulnerable area.

(For extra protection, consider wrapping the wire with electrical tape before sliding on the straw.)

If there's extra wire, loop it up and secure it with cable ties in a protected spot, for example under the handlebar.

Speedometers are a great addition to your bike.

No real explorer can be without one!

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