Really good iPhone GPS laptimer

[ChrisZang]

Q: Is it better than Harry's in all areas?
A: Well, beauty lies in the eye of the beholder...
For me it is. I didn't use Harry's a lot but here is where I see the the advantages of CMS over Harry:
a) predictive lap-timing: a GPS laptimer takes samples every 0.1 ~ 0.2 seconds (depending on which GPS you are using), which means you have hundreds of virtual beacons in one lap. CMS (and for example AIIM Solo) take full advantage of this and display "Time since last been here" a.k.a. "predictive laptiming". You get instant feedback if you're slower or faster than your last lap, ANYWHERE on the track, not just when passing the start/finish line
b) CMS allows portrait and landscape mode, Harry only allows portrait. My iPhone is attached to the windscreen and I like it out of the way as much as possible, Obviously with landscape mode it's much easier to do that
c) Video recording. If I recall it right, when Harry's is recording video, you no longer see your laptimes while you drive. With CMS you still see your laptimes (you get the same screen no matter if you're recording video or not), the video is rendered after the session is over
d) I am not sure if Harry's allows you to compare two lap side by side in the lap analysis screen, CMS does
e) Where Harry currently has an edge is OBDII data integration (and display of current gear - if you have OBDII), I understand that CMS is working on this as well

Q: How do you mount your iPhone on the rollbar?
A: I don't and have no plans to (I am using a GoProHD for that). My main objective for the laptimer is to see my "predictive" lap times while driving, and for that the iPhone obviously needs to be in-sight and therefore is mounted to the windscreen.
What I do like however is the fact that just a few minutes after the session is over (when the rendering is finished) I can review my lap with video and "telemetry" on my iPhone
One video for a 20 ~ 25 minutes session is a little less than 2 GB, so make sure you have enough free space.