Here is an example.

http://bonadjalins.wordpress.com/2009/04/04/testing-iphones-based-gps-lap-timersentul/

 

Nice...

 

A guy at work has one thats a dyno on his itouch. I havnt had a chance to try it out yet but I will see if I can borrow it this weekend on a ride. If I can, I'll post up how good it works.

 

iphone has shit GPS in it, I think less than 1Hz. In contrast tools like RaceLogic and others use 5 or 10Hz.

 

I know it's not GPS and it doesn't give you accel decel points but you do know there is a lap timer built into the instrument cluster don't you?

 

^^^ Yeah, that "lap timer" doesn't really work. It's worthless if you are a track rider. You may be off by like a 1/2 second to a second per lap if you try doing it yourself by hitting a button at the start/finish line... That's huge.

 

Blue tooth

I looked into this also. I'm no tech head, but the main problem is the gps reciever is deep inside the iphone and does not cycle quick enough for track riding. You can easliy test this out, just download speedbox lite (it's free) and test it next to a normal gps unit. The iphone will log your speed but it's just cycles to slowly. Works only if you hold a steady speed for 50yards or so? not really good enough for track riding. Although I've heard you can get round this by mounting an external bluetooth reciever which works much quicker? and yeah onboard manual laptimers are pretty useless for accurate lap times. I wish someone would come out with a cheap bare bones gps lap timer.

 

I looked into this also. I'm no tech head, but the main problem is the gps reciever is deep inside the iphone and does not cycle quick enough for track riding. You can easliy test this out, just download speedbox lite (it's free) and test it next to a normal gps unit. The iphone will log your speed but it's just cycles to slowly. Works only if you hold a steady speed for 50yards or so? not really good enough for track riding. Although I've heard you can get round this by mounting an external bluetooth reciever which works much quicker? and yeah onboard manual laptimers are pretty useless for accurate lap times. I wish someone would come out with a cheap bare bones gps lap timer.

Someone has. Search the WERA forums under the classfieds. Look for username "tunwlaguy" (sp?) and he sell them. I think they're about $300 or so. It actually has some pretty cool features.

I was about to get one, but my thumb has been pretty accurate with lap times when compared to an AMB lap timer. If you want proof, I can show my spreadsheets that shows the deviations. Some of them are by the thousandth of a second...which our built in lap timers do not record. There are occasions I either forget and a time logs down two laps instead of one or I mistakenly hit it too early or waay too late. I notice that tends to happen if I am trying to make a pass on a draft or out brake someone for turn one. So yes, ofcounsel is right. at first I was off by a lot, but after repeated practice and being honest with yourself having a good reaction, you'll get the hang of it. Its a good idea to do a trackday with organziations that have AMB lap timers like FastTrack so you can see for yourself how accurate your thumb is.

Here's how I do it. Once Im on the front straight, Im pretty much fully pinned on the throttle. I stretch my thumb out ready to hit the starter button. I tuck my head more for aerodynamics and to get a better nearsided view and look slightly off the side of the bike. So once I see I passed the start/finish line, I hit the button. The track Ive noticed is the most difficult to do this is at is Buttonwillow because the start finish line is so faint.