I've had a cateye wireless computer on the bike for some time but I wanted something that would give me a bit more data about my rides without having to go all out with a bike specific GPS.
Browsing through the app store I came across the Runtastic app which had good reviews and thought I'd give it a go. So for the price of a wireless computer I bought the app and a weatherproof handlebar mount for the iPhone.
On it's own the app is supposed to give you information on speed, climbs/descents as well as live mapping of your route. You can also analyse your rides later and view detailed information on pace vs. altitude climbed, time per mile etc etc.
There are outboard wireless sensors available that will also record heartrate, speed (more on this in a bit) and cadence but these are quite pricey and I imagine once you've purchased the app plus a handlebar mount/case for your iphone plus all the sensors you're probably knocking the door, price wise, of a decent GPS bundle.
The display is cusomisable to a degree and you can move things about so you can see the data that is relevant to you and remove the bits that you don't need to see.
At the end of the ride you can also upload the ride data to the Runtastic servers and analyse it or download it later. The app also integrates with Twitter and Facebook and you can enable realtime tracking so that anyone can go to the Runtastic site and see your progress. Personally I think this is also a good tool for burglars to use to see when you're leaving your house and how far away from home you are so they know when to strike when you're not home and not likely to be there for a while.
In use I find the display can be hard to read. I've not used it enough perhaps to have become used to where everything on the display is but most of the time I keep my eyes on the road and not on realtime data coming of the device but when I do look down wanting a stat I often find myself not able to find it before having to concentrate on the road again.
My other gripe is the GPS enabled speed information. Now I don't know what GPS capabilities the iPhone (in my case 3GS) has but I have a feeling the app is using the triangulation of receiver masts to pinpoint location and thus work out speed. I say that because of having used an in car GPS which I know is talking to satelites and shows MPH extremely accurately. I can't say the same for the Runtastic app. The speed is totally inacurate most of the time which is obviously why a speed sensor is available for the app to use and guage speed more accurately.
Having said that, when looking back on post-ride data it does seem to sort itself out after the fact when viewing the charts and graphs available.
Speed isn't something I care about too much so it doesn't bother me that much that it tells me I'm doing 13.97 MPH when I'm closer to 22 MPH.
Again, I don't know what technology is employed when it comes to working out feet climbed/descended but there seems to be a variance over the same route on different days. I have been using this on my rides to and from work where the route doesn't vary and I know the Earth hasn't shifted and the hills haven't moved. Still, there is a good 50ft of difference at times when comparing the post-ride data over the same route..
The other thing I'm not impressed with is that the app is very heavy on battery use. My iPhone is quite new so hopefully not suffering battery issues yet but I still wouldn't be confident of getting more that two hours use using the app, whether or not adding the outboard sensors increases/decreases battery useage I don't know. You certainly wouldn't be able to use it for a long ride or a sportive event.
I know iPhone cases are available that provide the device with an external power source but these just up the price even more until it makes no sense using your iPhone as a GPS device and a bike specific GPS devide becomes not only (hopefully) more accurate but comparable for price.
So, as a replacement for a dedicated bike GPS system I think this solution fails quite badly. However, for my use of simply tracking rides and basic performance it does quite well. I used to keep a diary of my rides along with anything eventful but now this more or less does that for me. I can even add a note to a session if anything of note happened during the ride. It's also allowing me to compare my performance over the same route with some decent, if not totally accurate, post-ride data to review.
So 3 out of 5 from me for this one for the app alone. Adding the sensors might make a difference but as I said before, the price of doing so negates the app as a handy solution for not needing something like a Garmin.
iPhone case/mount with integral power supply, about 100.00
Wireless Speed/Cadence Sensor with receiver key, about 140.00
Heartrate monitor, about 50,00
Total, approx 290.00
Garmin 500 with all sensors, approx 250.00
I rest my case.