ajderzie

I've been thinking about getting a Garmin Edge 205 bicycle GPS for my mountian bike. It's pretty easy to make a wrong turn and ride for miles in the woods before figuring out what happened. The GPS receiver is very small and clips to the handlebars. It shows your route, speed, and elevation. It can also time your laps everytime you pass the beginning of your ride.

So it got me thinking... Could I use it for track days in the vette as well? It will store 1000 lap times and routes. It seems to me that it would be no different than the dedicated GPS track timers except this one is very small, portable and costs less than $300. I could mount it to the bike when I'm biking and to the vette for HPDEs. Has anyone used this or are there any comments? Thanks!

TommyBoy72

You should try it. The Traqmate and MaxQdata basically work on the same principle. If its a flop for the track you at least have another use for it.

Gary04Z06

Most HPDE events do not allow you to time your laps. As they say "its not a racing school". Hide it well.

ajderzie

I use the term very loosely... I didn't want to keep writing "track day"

jlucas

You'll want to find out what Hz the GPS operates at. 1Hz isn't going to cut it for track use. I looked at the PDF of the manual and they don't say in there, so you may have to call/email Garmin.

rbl

I disagree and mine works perfectly. I had it in Richards’ T1 Vette at VIR and rode with him with a stopwatch in hand ... right on the money.

The higher update rates are more of a buzz sales pitch that actual functionality. The higher update rate will give you more speed information (closer spacing) which is useful for corner data. However, I found it to be information overload with my G2X data logger.

Satellite resolution via GPS is about 10' under ideal conditions (except survey stuff for $15K). It does not matter if you have a 50 Hz module or a 1 Hz module ... same resolution. I suspect the Garmin uses a 1 Hz as this is the standard unit.

With 5 Hz you get 5 fixes per second but the accuracy of those 5 fixes is only within 10’. With a 1 Hz unit you get 1 fix per second but it too is accurate to 10’. Even with 1 Hz updates, clever math skills and some averaging will result in pretty accurate timing and also predictive lap timing. Mine is and mine also does segment times. No GPS based system will ever be as accurate as a beacon but for 99.9% of our use it is more than acceptable. I am completing the application SW for the PC now and hope to release a final version soon. Under $500 too with 30 hours of data storage!

I suspect the Garmin unit is pretty accurate also.

jlucas

Let me know when you have something available for testing. I would like to check it out. I've consulted with 4 of the current GPS based D/A makers on their software functionality and features.

My comment about 1Hz was not about positional accuracy, but due to the distance traveled at 130mph (NCM VIR while going by the start finish line) in a 1 second time span. I was assuming that Garmin wasn't putting in interpolation logic into a device designed to go on a bicycle.

73-84 IMSA Widebody

I have a Garmin Nuvi, would it be useful on the track? Has anyone else used/tried one?
David

ajderzie

track day at pocono next week. I'll update on how it worked

rbl

I think you will find it works but will only have 1 second resolution which is huge. However, that will give you some feel for what is going on. Unfortunately you won't know which side of zero you're on so it may actually give you a little more error.

My Garmin 91 works the same and it draws the track map, etc. Just not real accurate.

TommyBoy72

Speaking of which is it worth mentioning take very careful thought to where and how you mount it. On my buddy's MaxQdata, if I tape/velcro the bluetooth GPS receiver extremely far forward on the dash, it works great. If I get lazy and just put it in the cup holder, it naturally is much less accurate as it cannot acquire as many satellites and with a weaker signal strength.

ajderzie

Ok, back from a rainy Monday at Pocono. It was very wet and the time trials were cancelled. I have to say thought that the Garmin Forerunner 205 wrist GPS timer worked great. It seemed relatively accurate. It counted laps, distance, max speed, lap times, elevation. It drew a map which is relatively useless unless you want to look at section times (takes a little extra effort to mark the sections you want splits on). I still would like to try it during a time trial to see how close it comes to the electronic timer. Overall, acceptable, cheap, portable, multi-purpose. For me it was perfect.

rbl

What was the resolution on the time? Seconds or tenths or hundredths?

Oyishdog

I just found that one on sale on Amazon for $161...that seems like one hell of a deal if it works, which is sounds like it does.

Miaugi

ajderzie

One thing to keep in mind is that it is a 1 hertz gps which means that it checks its position every 1 sec. The expensive gps track timers are 5 hertz which means they check their position 5x a sec.

The first lap I would start the timer it would measure to 100/th of a sec. Every lap thereafter it would be to the second. The total time would once again be to the 100/th because I would stop the timer manually. (This part I just realized today when I reviewed my times to write this)

I also started the timer at the slowest part of the course so their would be less change in position every second and thus would hopefully be more accurate.

Overall, for my use it was great especially since I use it on my bike as well. I would have loved to have accuracy to the 100th of a sec but at least I can get a pretty good idea of how fast I'm running. I haven't done this yet but you can also divide the course up into pieces and get section times as well. The data also downloads to the computer and can overlay on to a map (Haven't done this either). Another thing you can do with it is time a distance. Probably not great for a 1/4 mile but maybe for something longer?