I had one for a little while. I realized after I lost it that I spent all my time staring at it. It fell off one dark morning, who knows where, and I remembered one of the primary reasons I ride- to look at the world unfettered. I spent no time looking for that little digital prison, and I've been a happier cyclist ever since.

If you "listen" to your bike, it'll tell you when things are starting to wear, and might need replacement soon. You do have to listen close to hear the initial comments though! My commuter likes to have long conversations with me sometimes.

For commuting? No.
For other types of riding I use a GPS to record my speeds and tracks.

What I do want though is a small, waterproof clock-only gadget for my handlebars.

My main commuters I have them (cateye strada with cadence wired) but I find them being less and less important. One of those bikes was supose to sell and it got pulled off. Deal fell through and not sure I am going to bother putting it back on. I do like the cadence and I loosely keep track of my commuting miles and miles on the parts on the bike. Clock is bad about accuracy so I have to reset it every few weeks and even got lazy about that. The second one may end up on the Trainer (Trek Mtn on a Advocet trainer). I have no plans to add them to any of my other bikes that I like it keep understated.

I'm a very analytical person, so I enjoy all the extra data.

That and for some ego boost.

I don't see a point in them other than tracking miles and training for fitness/races. Bikes don't go fast enough on most terrain to warrant using one to measure speed. Knowing if I'm going 19mph vs. 20mph isn't a big thing for me. I know if I'm going fast enough or slow enough.

I know if I'm going fast enough or slow enough for races if I'm passing everyone else I see.

So, as it turns out, I know I'm going slow enough.

Over in the Road subforum, they sometimes talk about training with power meters. This would work in a situation like I described yesterday, which was riding loops in 20+ mph winds. My speed varied by nearly ten mph even with the same perceived effort thanks to whether I had the wind at my back or in my face. Keeping track of effort with a power meter would have been more useful and consistent, and likely less depressing, too -- 300 watts is 300 watts regardless of wind direction and road speed.

I treated that ride like I play golf -- I don't care about the score.

i use mine mostly for clock and therm. also for maintenance mileage

I broke one old and one new cyclometer in '07 and gave up on them at that point. One had a bad contact and finally gave up, the other fell off the bike and died instantly.

I track my mileage by bikely.com and a watch (or my cell phone) now.

I lost my old cyclometer and for whatever reason, missed the speed readout, so I bought a new one. The distance traveled is nice for new routes too.

I use it less for me and more for others. I usually get people on the train asking me how far I ride and that's when that thing comes in handy.

Just go get some cheap accessory to jack the attachment mechanism from, and epoxy on a large-faced digital watch or something.

I like to see how fast I'm going and like to look at the average mileage at the end of the ride. Also, I like to track my total miles on the bike from time to time.

Ride safe,

Jeff

This; my commute includes about 3/4 mile of school zone with no curb and narrow lanes, so I like to keep at least 15mph through there, without going too much over 20. It's a slight downslope, so with a tailwind, 24 isn't hard, but with a headwind, 12 can feel like 20.

I guess I do like having the speed readout there for the few times when I'm pretty sure I'm already going the speed limit, so I know not to bother being at all deferential to cars.

This is exactly how I use mine.

I have a Sigma 1609 on one of my road bikes, with an second mount for it on a touring bike, but the rest I don't use one. On the road bike I use a computer I have a cadence set up on that one, on the touring I don't care about cadence. But it's nice information to have to see how far I've gone, average trip speed, keeping my cadence in check, outside temperature which is great for touring. But the other bikes I have, I don't bother. I don't keep track of the data on a computer I just keep it in my head. Maintenance? My computer doesn't help me do that, any dope can tell when to maintenance on a bike without a computer.

I do like the wired computer better then the wireless. I had 3 wireless computers in 8 years, their just not reliable, and the sending unit ate batteries, but the button bats are cheap so that wasn't a big deal, the big deal was the sending units kept failing. So I went back to wire, so far the Sigma has been great.

No. How fast I goes is how fast I goes. How tired I feel is how tired I am.

No, I don't bother either. I bought one and used it for 2 weeks or so, to get a (somewhat) accurate milage count (everyday was different on the same route since it gave me 1/1000 of a mile). It gave me a general idea on how fast I was going, and then I lost interest. Towards the end, I felt myself kinda stressing out about avg speed etc, and that's when I got rid of it.

To know how many miles are on your bike? Aside from just wanting to know, it can help plan and budget for tire and chain replacements. Having a clock on the handlebars is really nice this time of year, when my watch is buried under gloves and sleeves, and I don't want to pull them back and expose my skin to the cold. Saturday, I spent much of the day on the bike; it's kind of nice to know that I rode 70 miles, instead of just "a lot." In theory, it might even help a person avoid a speeding ticket going down hill - I've at least read about cyclists getting those.

Plus, it's not like you have to wind them up like old watches, or actually do anything. You spend $30, once, and then a bunch of information is available if you ever want it, but pretty much out of the way when you don't. I'm not sure why anybody would want not to have one.

I broke down and got a Garmin Edge 500 a couple of months ago, and it was the best commuting investment I have made. It tracks my progress, miles and the Garmin Connect site is the cherry on top. If I somehow lost it, I'd ride directly to the bike shop, not passing go or collecting $200, to buy another one.

I use an old Garmin Forerunner 301 because I'm geeky and I like the data. It incorporates a HR monitor, which is nice in terms of seeing my 'level of effort', and it keeps track of my ascents, descents, speed, pace, and distance. It also has this little 'calories used' number which really makes me feel good (even though I know better than to believe I'm burning 2200 extra calories commuting each day).

At the end of the day, does it get me to work faster, save me time, make my bike more efficient, or otherwise matter? Heck no. But I like knowing, and charting, and keeping track. And like someone above, if/when it breaks, I'll likely replace it.

I just got my Garmin 705 back in June. Its awesome! Not only is it navigation, but it also records.
I've been also using an old Go Pro Hero cam, off and on, but mostly carry a canon digi cam, which is not as effective as simply having a video recorder running the whole time...

with GPS and video.. it's simple documentation.

as we all know, its amazing what you see when on a bike.

A cyclocomputer probably would have prevented my knee problems.

My first four years commuting I timed the 9 mile ride to work uphill with a watch. It was fun to see my times improving. As I got stronger, I shifted to higher gears and my cadence reduced, causing a knee cartilage injury. After two months off the bike and some physical therapy I'm finally recovered. Now my Cateye Astrale 8 displays cadence in big easy-to-see numbers. Plus I'm faster now that my cadence is always above 80. Commuting 90+ miles a week at low cadence can eventually damage your joints.