I'm looking to get a bike computer, primarily for the speedometer function. I use my bike on a trainer most of the time, and I'd like to get "speed" from that, so the sensor needs to be on the rear wheel.

I'd prefer not to spend too much, but my budget is pretty high. Right now, the only feature I want is speed, but I'll learn to use any other useful features.

I've read this question, and gotten some interesting data, but I don't really care about whether the unit is wired or wireless. It just needs to reach the back wheel and be reliable.

  • Well, you should probably decide wired/wireless, since that's a major differentiator. Also, do you want cadence? (Don't know about currently, but at one point most non-cadence meters where front wheel.) Apr 14, 2012 at 22:20
  • @DanielRHicks What's cadence? I really don't care whether wired or wireless, I just want the best one.
    – Cajunluke
    Apr 14, 2012 at 22:37
  • @CajunLuke, Daniel means the cadence of your pedalling (so you can measure how constant your pedalling is and check if you keep it in the most efficient numbers for your riding style). With rear-mounted sensors, this is relatively easily achieved, as you can see on the second picture here. Apr 15, 2012 at 0:03
  • Unless you use a small frame most wired "speed only" units don't have enough wire length to reach the bars.For my trainer I fabricated a mount for my quill type stem.
    – mikes
    Apr 15, 2012 at 2:04
  • 2
    If It's a possibility for you to mount the speedometer in the top tube, almost any computer will serve the purpose. Specially using the bike in a trainer where looking up is not a priority...
    – Jahaziel
    Apr 16, 2012 at 21:02

6 Answers 6


I've decided to go the cheap route - I got a Cateye Enduro 8 (which is wired, but not long enough) and I'll modify it to extend the wire.

If I start using my bike more (or I break the Cateye) I'll look at getting something like the Garmins @zenbike mentioned.

  • 2
    Modifying the wire is iffy at best. There are real wheel wired designs but they aren't easy to find anymore.
    – zenbike
    Apr 17, 2012 at 4:31
  • 1
    @zenbike I had several EE courses in college, I know how to solder, I can test the wire to make sure the output is the same as it would be pre-modification, and I'm willing to throw the thirty bucks down the drain if it fails. Plus, it'll be fun.
    – Cajunluke
    Apr 17, 2012 at 5:33
  • 1
    @CajunLuke - You should do an Arduino wireless thingy and have even more fun! ;~)
    – user313
    Apr 17, 2012 at 5:52
  • 2
    The problem with the wire is that it's apt to be "tinsel wire", which cannot be soldered -- you must use crimp connectors. Apr 17, 2012 at 15:47
  • 2
    @DanielRHicks I'll keep that in mind, thanks. If that's the case, I'll probably just replace all of the wire.
    – Cajunluke
    Apr 17, 2012 at 16:08

This problem I have encountered myself, the wire length of most digital speedo's is not long enough to reach and be actually useable, the range of wireless speedo's are not good enough either, considering that you are only an extra 2 foot away from the receiver seems a bit much.


A cheap wired speedo is your answer, replacing the wire with a longer one is the only cheap method which reliably works, you will need to use copper wire as it better at conducting electricial impulses compared to the cheap alloy use in the standard wires, test before installing to make sure your shed altered speedo actually works.

(Cheap speedo = £5) + (length of suitable copper wire = 50p) + (ten minutes worth of time) = problem solved

  • 1
    But finding good wire, suitable for the task, is difficult, as is splicing it. Dec 29, 2013 at 0:45

The best single sensor, rear wheel mounted computers are made by Garmin.

The Edge 500 or Edge 800 are amazing, if a bit pricey. They do have pretty much every feature you could want in a cyclometer, and an easy to mount, stable, rear wheel only sensor.

  • I'm going to be using this inside on a trainer a lot - I assume a GPS-based device wouldn't work?
    – Cajunluke
    Apr 15, 2012 at 23:47
  • The Garmin devices have the ability to track GPS location, but they use a wheel sensor for accurate speed and distance, and as such are not limited to GPS connectivity. I use my Garmin with my trainer regularly.
    – zenbike
    Apr 16, 2012 at 2:42
  • I assume the Garmin units reach the rear wheel since you use them on your trainer?
    – Cajunluke
    Apr 17, 2012 at 5:36
  • @CajunLuke - Wireless. Pretty sure that the sensor does not care whether front or back. Mine is on the front, but see no reason as to why it wouldn't do the same job on the back wheel.
    – user313
    Apr 17, 2012 at 5:45
  • They are designed for rear wheel use, as that allows one sensor to work for both cadence and speed. It could be mounted on the front, but you'd lose the cadence.
    – zenbike
    Apr 17, 2012 at 6:40

The Bontrager Trip 3 is now offered as an inexpensive, rear-wheel-sensor computer with cadence. Mine seems to do everything you'd want it to (measure speed and cadence, not catch fire.)


Time and tech wait for none of us. Since this question was asked and answered 7 years ago, the smart trainer has become far more affordable and achieves your needs, at a cost.

These devices fit your bike in one of two ways:

  1. replace your rear wheel+cassette, and support your weight while riding.
  2. Hold the bike by the rear axle, and let your existing tyre turn a drum via friction.

In both styles the bike's front wheel remains on the floor but doesn't rotate.

Manufacturers include Tacx, Wahoo, Cycleops, and a bunch of other brands (no brand recommendations are given here).

enter image description here enter image description here

The difference between these and the indoor trainers of before are that modern trainers will talk to a head unit or laptop or tablet via ANT+ or maybe bluetooth which is wireless.

Separately, indoor trainers like this can be used to complete "virtual rides" like zwift or trainerroad or a bunch of other services. These take your output powers and send them over the internet to servers, that progress you through a level as though you're out riding for real. Extra accessories can change the angle of your bike to simulate up and down hill grades.

Downside is the cost - all of this could cost more than your entire bike, and hundreds of times more than an 11 pound cateye bike computer with a bit of added bell-wire and some heatshrink.

Complete "pain cave" setup example - utter waste of aero-bike http://i43.tinypic.com/j0gnz7.jpg from https://forum.slowtwitch.com/forum/?post=4831459


Probably any wired cyclocomputer with cadence will have rear wheel sensor near crank. I had Blackburn Delphi 3.0 Wired Bike Computer with Cadence. This was not the best cyclocomputer, but at least it's that you asking for.

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