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Any luck with cyclocomputers with altimeters?(12 posts)

Any luck with cyclocomputers with altimeters?jfd141
Aug 5, 2002 6:47 AM
I'm interested in purchasing a cyclocomputer with an altimeter function. Seems really cool, but I'm a little skeptical how accurate these things work? They just use air pressure? Does severe weather throw off the readings? I'm curious what kind of experiences owners of altimeters have had? I'm thinking of purchasing the Cat Eye AT100 Computer with Altimeter on performancebike.com (60 bucks on sale, seems like a good deal). Any feedback would be appreciated.

John
Nomr_spin
Aug 5, 2002 6:55 AM
This has been answered in detail on this forum before. Maybe a month or two ago. Do a search if you are interested.

My experience with the AT-100 is that it is not reliably accurate, especially near sea level. It worked wonderfully at altitudes over 5000 feet. The manual even says the algorithm works best over 3000 feet. I happen to live at 196 feet, which makes it fairly useless.

You also have to calibrate it at least every ride, which is annoying, and you have to know what your current altitude is (a chicken and egg problem). I still have it on my bike, but I don't use the altimeter features anymore. Just like Miss Cleo, it is for entertainment purposes only.

I have a Suunto altimeter watch which is much more accurate.
Polar S710PODIUMBOUNDdotCA
Aug 5, 2002 8:44 AM
You know its a lot more money but I'd almost recommend saving up your money and buying the Polar S710. An absolutely great HRM with an altimeter/speedometer in it as well. With the option to get cadence and power down the road. This combined with computer uploadability that plots your speed, cadence, power, altitude and hrm its a super cool toy and a fabulous training tool.

Cheers,
Nick
PodiumBound.ca
Specializedcyclopathic
Aug 5, 2002 7:27 AM
4 guys in our group have Speedzone Pro and the reading at the end of typical 5,000-10,000' century will be within 100'. It is usually very close to TopoUSA (~500-800' less). Only problem '01 used to reset after 12 (or 20?) hours.

Cateye readings are usually all over the place, you may ride same route with same computer and get 2,000-3,000 diff, esp if battery gets older.

yeah Speedzone is 40$ more but you get what you paid for
re: Specializedcyclopathic
Aug 5, 2002 7:35 AM
it also has a thermometer, inclinometer and a bunch of other features, here is the link http://www.specialized.com/SBCEqProduct.jsp?section=11307&browselevel=top&JServSessionIdroot=mfxk21tirm.j27004

unfortunately cadence isn't wireless :-(
Dead battery ...Humma Hah
Aug 5, 2002 9:54 AM
My Cat's Eye with a dying battery declared that a very flat century I rode last summer involved a total climb that would have been comparable to the Death Ride.

With a fresh battery, it is fairly consistent. If you're getting erratic readings, I suggest you check how the static port is oriented with respect to the relative wind striking it. If you're forcing wind into the static port, it will read an erroneously low altitude.
Misunderstanding of what they're supposed to do, I thinkcory
Aug 5, 2002 7:47 AM
I've had two, and they drove me crazy at first. I was complaining about it to a friend who's a pilot and an engineer designing weather (and other) instruments, and he dope-slapped me.
"You want the thing to tell you when you climb 20 feet," he said, "but you don't want it to react to changes in atmospheric pressure. It's impossible."
He gave me a half-hour lecture, but the short version is that altimeters work by reading atmospheric pressure, which varies not just with altitude but with temperature and weather changes. Mine would measure the difference between the first and third floor of my building, a really tiny change. If you're going to have that sensitivity, he said, you have to live with your house being at 4920 feet when you get up in the morning and 5140 feet at noon.
A partial fix is to reset the thing often at known elevations. I live at 4904 feet, work at 4440, the first summit on my mountain bike training loop is 6140--you need to calibrate the thing before every ride, not set it at Christmas and expect it to be accurate in August.
re: Any luck with cyclocomputers with altimeters?js5280
Aug 5, 2002 8:15 AM
Been happy w/ my Cat Eye AT100 for about 4 seasons now. I have it on my mt. bike. I live in Denver so I'm riding tween 5280 and 12000 ft. It's actually pretty consistant in my experience. I use it mainly for pacing, particularly new trails. . .you can look down and have a good estimate of the remaining climb if you know the peak elevation. If your rides don't climb more than a few hundred feet though, it's probably not all that useful to have an altimeter.

I have to admit though, some of the new altimeter computers are really cool, have more features, and aren't too much more expensive. Some of them will compute %grade which I think is more useful data than just altitude. I can tell you though, a computer won't make you any faster unless you use the data it provides.
expectationsDaveG
Aug 5, 2002 8:26 AM
My Cateye 100 works fine but I think its a matter of expectations. Those that are unhappy with them can't accept the inherent varability that a device that works from atmospheric pressure causes. My main use for it is the accumulated altitude feature. This helps me quantitively gauge the hardness of a hilly ride. If you want it to give the same absolute altitude at a given point day after day you will be unhappy. Using the altimeter on the same course over several rides, the error in the accumulated altitude is about +10%. I consider it a fun toy with soe limitations.
Polar S710PODIUMBOUNDdotCA
Aug 5, 2002 8:50 AM
Sorry I posted this under the wrong topic.

You know its a lot more money but I'd almost recommend saving up your money and buying the Polar S710. An absolutely great HRM with an altimeter/speedometer in it as well. Then it has the option to get cadence and power down the road. This combined with computer uploadability that plots your speed, cadence, power, altitude and hrm its a super cool toy and a fabulous training tool.

For the record all barometric altimeters are affected by weather so you do need to reset it at least every couple days. The ultimate is a GPS unit but the thing is they are super hard on batteries and very bulky. So your best bet is to go to the nearest radio shack or outdoor store which has electronic gizmos... ask to take the GPS outside and take the altitude off of it then program it into the altimeter. Go straight home and record this number and use this as your base point.

Cheers,
Nick
PodiumBound.ca
I use a Cat's Eye AT-100 ...Humma Hah
Aug 5, 2002 9:51 AM
They are not perfect, but they work OK. All pressure altimeters, including those in aircraft, have inherent drift due to changing local air pressure. I am a pilot and my job involves doing calibration of altimeters on UAV autopilot systems.

The AT-100 has a 5-ft resolution, and when you do a measurement of a particular hill's height, it will probably be accurate within about 10 ft.

Over the course of a day, it will drift with atmospheric pressure, and also with temperature. In some mounting positions, it may be sensitive to speed as well. This affects its long-term accuracy.

For total climb, in addition to the errors above, small fluctuations in altitude will show up as accumulated climb. Total indicated climb is almost always higher than actual on long rides, particularly with a lot of flat riding.

For the money, the Cat's Eye is not bad. However, it does lack a feature I would like, a readout of percent grade. That should be pretty easy to incorporate in the design. Rate of climb in feet per minute would also be handy.
Speedzone Promapei boy
Aug 5, 2002 11:15 AM
I'm quite happy with my Speedzone Pro. Yes, you have to take the altitude measurement with a grain of salt - the altitude of my house varies about seventy-five feet, depending on the time of day - but when you're measuring a 700-1000 foot climb, 75 feet plus or minus really isn't that much. As for the inclinometer, it's a real treat. Utterly fascinating. It also improves your eye. Eventually, you begin to be able to eyeball climbs with pretty good accuracy. The temperature gauge, by contrast, is iffy at best. If you're riding in direct sunlight, it can add ten to fifteen degrees, easily. Hope this helps.