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,
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
|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
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
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
||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
(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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