Cateye bicycle computer...on VFR

Hi ladies and gents,

I have been thinking for a while about purchasing a bicycle computer to put on my VFR, so I can calibrate and know my true speed. I thought I would post my results just in case anyone else wanted to know.

On Saturday, I purchased the Cateye Velo 5 bicycle computer from a local bike shop for $19.99. This is Cateye's simplest model, and includes odometer, trip odometer, speed, max speed, and clock. The odometer is only capable of reading 9999.9 miles, but I didn't care about that. The speedometer, however, is capable of reading up to 180 mph, and of course, displaying your top speed.

The unit comes with a round magnet, which is just slightly smaller than the holes in the rivets for the semi-floating rotors. You could probably mount it in there with a small amount of JB weld. I had a magnet that fit perfectly in the rivet, so I pushed it in after applying a small amount of Bondini gel (super glue). The pickup unit mounts to the fork with zip ties, and needs to be within 5mm of the magnet, which is easily achievable. After installing the display mounting bracket on the upper triple clamp with double sided tape, I calibrated the unit to the measured circumference of my front tire; 187cm. My front tire is a stock size 120/70-17 Dunlop D220, and should be very similar to any other 120/70-17.

Next, I rode along a quiet road with mile markers to determine the accuracy of the odomoeter calibration. It was within .05 miles. Yes, that's 5/100 of a mile. I'm calling that close enough. I know for sure it will read up to 120 mph, since I achieved that speed on the way home yesterday. That was only to test the unit, of course...:bs:

It's a very simple unit to install and setup, and for $20 I know my true speed. This is nice if you have different size sprockets, tires, anything else that may throw off your speedometer, including the factory setup. I still don't understand why the manufacturers build in speedometer error. This is also nice if you have made modifications of the sort and would like to know the true mileage from origination to destination.

 

Ha, I love it. Not a bad idea i'm sure everyone has instaled one on the bike bike at some point, not sure why i never thought to use it on the cycle...hmmm

 

These are great if your bike (not the VFR) does not have a tripometer. Some models have a backlight that enables night time reading. Most are waterproof. Is the Velo a wired or wireless model. Thanks.

 

Wired

The Velo 5 is a wired model. This was my preference for a couple of reasons. One, it was cheaper than the wireless models, and two, the batteries will last longer in the wired model.

 

If you are going wired, get a mountain bike specific model with the heavy wire. Like the Cateye Enduro.

Also , for the most accurate readings, mark your tire and measure the distance it travels in one revolution. There is a chart in the instructions down to the mm.

 

The bicycle speedo will not be any more accurate. Once you climb above 40mph your tire expands and the diameter changes slightly. The only way to get a TRUE reading of speed is to use a GPS. Calculates speed by relative position on the earth surface, not by revolutions of your wheel.

 

I think the bicycle speedo is still more accurate than the stock speedo. I've used a gps and found the stock speedo to be 8-10% fast.

 

I carry my Garmin Edge 305 (cycling computer) that I used on my Orbea road bike. GPS based. You can download everything to your laptop including your map, etc...

The Garmin Edge 605 is my next toy. The map on it is awesome. Looks like the Nav display in the car

Raisin is right though. Pretty interesting to see your average, max, etc... Now, gotta find a way to read endurance, average fuel burn...

 

My speedo is broken and I duct tape my garmin etrex to the dash. Ghetto, but effective.

 

Hey raisin, are you still using this computer? If you are, you can test terry's theory by redoing your test run but not exceeding 40mph. I'd be curious to see if the mileage becomes more accurate. Thoughts?

 

Interesting ideas. Great experiment! And I am a long-time user of bike computers on human powered vehicles (I bought the first unit--THE PACER--in 1979. It was about as large as a Blackberry! I have used multiple computers since then.) I agree that calibration is critical (measuring the EXACT circumfrence of the wheel (while inflated to actual pressures and while the bike is loaded up with the typical weight (rider/gear) it will see when riding. Then, there is the accuracy of the computer...some are better than others and there is also a variance within the model (I have seen this when using two computers on one harness on my tandem). Then, when you check it against a mile marker, please be aware that those highway markers are often quite poorly placed. On my regular ride there are several that are very "short" and one that is "long." Mr. Highway Guy is tasked with only a vague accuracy so be sure to check your results over at least 10 miles. And in my opinion, 5% accuracy is only average. With some careful calibration of the unit you should expect about 1-2%. Any measurement device has error. GPS, bike computers, laser/radar devices...they all are variable in their errors. If you really want accuracy you need to go to great lengths like a professional racing timing trap. Like many of us, I want as much accuracy as I can get from things like my VFR's speedo but mostly I just twist and enjoy the ride.

 

My bicycling computer mounted on the VFR agrees with the GPS at all speeds up to around 90mph, after that I don't try to check.