In reply to Alan James - Rockfax:
> Does a bike computer offer much that you can't get from a mobile phone on a decent bike mount?
An excellent question and the answer is not much. When I was having problems with my Garmin in Flanders I was recording my ride on my IPhone, and the battery held up for a full days ride (100 miles), with a few photos and texts as well. And since I often like to listen to podcasts on the bike, then having controls for that would be good. Not to mention being able to see texts and other notifications - think the newer Garmins may do this.
However the screen doesn't stay on, so not sure what it would be like using it for nav or simply checking your distance etc. and I often like to keep an eye on the gradient profile when climbing so I can measure my effort to get to the top without dying. Suspect you'd start running the battery down quicker if you access the screen a lot, not to mention it being a pain if wearing gloves.
Garmin devices are pretty robust, so less likely to get damaged in a crash. And of course if you have a crash bad enough to damage something on your bars, the chances are you are going to need to call for help.
I'm surprised no-one has produced robust and integrated bike mount/battery pack, but last time I looked there wasn't anything.