When it comes to altimeters, you have your choice of three different types: wristwatches, bike computers, and hand-held units. This article will focus on the first two since they are the most usable on a bike. The information for this article is gathered from personal use of a Polar XTrainer Plus, an Avocet Vertech, and an Avocet 50; from research on the web of manufacturer's sites; from opinions on the web; and from years of paying attention to bicycle equipment.

Watch/bike computer comparison

• Features: watches have more features available, usually including temperature. Bike computers are usually limited to current altitude, trip altitude, and cumulative Altitude.
• Ease of Use: bike computers are easier because of the limited number of features. Watches will require more learning. Watch features will be easier to remember if you use them frequently. Watches are more versatile for use in any sport.
• Handlebar Space: a watch is another device to attach to your handlebar.
• Cost: expect to spend $70-$100 for the bike computer, or $150-$300 for a watch.
• Manuals: for the watches, manuals are a necessity because of the number of features. Be sure to keep it around.

Altitude Adjustment
Altimeters use pressure sensors to detect changes in atmospheric pressure. Using the pressure readings, formulas calculate an altitude that is displayed on the screen. Differences in pressure over time are used to calculate total ascent or descent and rate of ascent or descent. Because the altimeter relies on barometric pressure, altitude readings will be affected by changes in pressure even if you haven't changed altitude. Pressure changes occur because of changing weather.

If you want to maintain accurate current altitude readings you will need to reset the altitude fairly frequently (daily is usually sufficient). If you are primarily concerned with cumulative altitude gains, you don't need to reset the altitude for each ride since cumulative gains are relative only. Because of the need to reset the altitude on a frequent basis, I paid special attention to the instructions on how to reset the altitude for watches. I haven't done this for bike computers because most computers are simple in comparison to the watches.

Battery Replacement
One of the hassles of owning a watch altimeter (and a HRM) is that it is generally recommended that you return the watch to the manufacturer to have the battery replaced. This ensures the watch retains the waterproof seal and the manufacturer can re-calibrate the sensors. In some cases, failing to do this will void the warranty. Most batteries have a life of 12-18 months. Having the manufacturer change the battery will cost $20-$25 which includes postage to and from the manufacturer, the battery, and labor. It may take anywhere from a week to several months depending on the manufacturer. I find the process a hassle. Having the battery replaced locally by a jeweler will cost about the same, but without the delay.

Suunto is one exception ó they advertise that you can change the battery. When I was in REI recently I saw a Suunto battery replacement package for sale. This package included a new o-ring which a local jeweler may not have.

In all cases, it's best to at least have a jeweler or watch repair person change a battery. No similar problems exist with changing batteries on bike computers with altimeters.

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Recommendations

• One bike: Try the Specialized - and I do mean "try" since the model is new. If you find someone willing to sell an Avocet 50, get that one ó there are many who can vouch that it works.
• More than one bike: Either get extra bike mounts or get a watch. Either way you can swap among bikes.
• If you hike, ski, do mountaineering, or end up in the mountains, go for the watch. You can use the watch for these activities as well.

What watch would I buy? I'm torn between three ó the Suunto, the Avocet, and Sports Instruments. Suunto has great quality, but has too many features that would never be used. Avocet has a good set of features, a good manual, but at times has occasional lapses in quality control and I wonder if Avocet will stay solvent as a company. The Sports Instruments model has a nice look, a few more features than the Avocet, and a concise manual.

Review of new Specialized Speedzone Classic and CicloSport Ciclomaster 414 Alti

Notes
More Space
With a bike computer, altimeter, heart rate monitor, cue sheet holder, and a light on your handlebars, you don't have much room left for your hands. Sidetrak, Minoura and Performance all have accessories which add a bar 4-6 inches long in front of your handlebars. The models are Excess Access, Space Grip, and Space Bar respectively ó none cost more than $20. You can also make your own using Spinaccis or cutting up an old pair of handlebars.

Bike Mount Alternative
Instead of spending $10 on the bike mounts most companies sell for their watches, go to the hardware store and get some pipe insulation. Three feet costs less than $2. Cut it with scissors. When it wears out and get squished, throw it away and cut another piece off.