Forerunner 305 - Reliable?

moscowflyer

Compared to a cycling specific Garmin?

I'd be interested to hear from anyone who's used both, as I'm not convinced by the speeds my Forerunner gives me.

amaferanga

Don't have a 305 but I do have a 310xt and have had zero problems with it. What's the issue with the speed? Does it fluctuate or is it the average value you're not convinced by? I would imagine that the FR205/305 and the Edge 205/305 will have very similar software/hardware.

avoidingmyphd

absolutely reliable (i use an edge 705 and a forerunner 305)

one possibility: do you have a wheel sensor? if so, is it calibrated correctly?

V5ade

According to my Forerunner 305 I've hit 66 mph a couple of times on my MTB (Off road!).
I think that it may be slightly optimistic at times

moscowflyer

I don't use a wheel sensor, just the 30f on my wrist.

I've been out of the saddle for four years but seem to be hitting averages on the same level as I was when I stopped cycling before, when I was two stone lighter and ten times fitter than I am now, which doesn't seem right. Of course, I'm happy for it to be right, just surprised by it.

amaferanga

MoscowFlyer wrote:

I don't use a wheel sensor, just the 30f on my wrist.

I've been out of the saddle for four years but seem to be hitting averages on the same level as I was when I stopped cycling before, when I was two stone lighter and ten times fitter than I am now, which doesn't seem right. Of course, I'm happy for it to be right, just surprised by it.

Pretty easy to verify if you just time the ride and plot the route on an online mapping site. That way you can verify the distance the watch is reporting and the average speed.

Could it be that you're looking at moving average now where as before you were looking at the regular average including stops? Got any Garmin Connect links to the rides?

What were you using for speed/distance before? Maybe you had the wheel size set wrong on your bike computer?

moscowflyer

amaferanga wrote:

MoscowFlyer wrote:

I don't use a wheel sensor, just the 30f on my wrist.

I've been out of the saddle for four years but seem to be hitting averages on the same level as I was when I stopped cycling before, when I was two stone lighter and ten times fitter than I am now, which doesn't seem right. Of course, I'm happy for it to be right, just surprised by it.

Pretty easy to verify if you just time the ride and plot the route on an online mapping site. That way you can verify the distance the watch is reporting and the average speed.

Could it be that you're looking at moving average now where as before you were looking at the regular average including stops? Got any Garmin Connect links to the rides?

What were you using for speed/distance before? Maybe you had the wheel size set wrong on your bike computer?

I was using an Edge 305 before. The average includes stopping times as I checked that yesterday. Maybe it's simply a case that the legs are still there, I hope they are! I just wondered if there was anything with the 305 when cycling, with it being on the wrist as opposed to on the bars like the edge was. I'll try the map thing, I'll also be buying an Edge before too long so I'll be able to compare the two.

Cheers.

derbygrimpeur

If your using it based on GPS and not wheel sensor, the distance travelled (and so speed) will not be 100% accurate. Why not just get a cheap cycle computer with wheel sensor and get an accurate reading?

moscowflyer

derbygrimpeur wrote:

If your using it based on GPS and not wheel sensor, the distance travelled (and so speed) will not be 100% accurate. Why not just get a cheap cycle computer with wheel sensor and get an accurate reading?

Any recommendations for a decent cheap one? I assume Cateye are still decent for that sort of thing.

derbygrimpeur

That's what I'd go for

http://www.wiggle.co.uk/cateye/computers-gps-watches/

5 function computer for £13.49

I've got a "Micro" (I think) at home that I no longer use. Am happy to post it to you if you cover the postage costs? PM me if you're interested.

moscowflyer

derbygrimpeur wrote:

That's what I'd go for

http://www.wiggle.co.uk/cateye/computers-gps-watches/

5 function computer for £13.49

I've got a "Micro" (I think) at home that I no longer use. Am happy to post it to you if you cover the postage costs? PM me if you're interested.

Thanks! PM sent

furrag

I used the Garmin 305 Forerunner last year. Good, except the tanlines and having to look at your wrist. I noticed (and there's a specific website) that highlights the elevation is a little off when mounted on the handlebars. This is due to the GPS receiver facing down when in this position. I eventually bought an Edge 705 for the maps feature as I wasn't keen on following a black line on the 305FR.

If you want basic live and min/max/ave data, then a cycling computer is for you. If you think you'll analyse how many miles, climbing, time spent in HR zones, routes etc in other software as well as the added benefit of workouts, a Garmin is for you.

danowat

I use a 405, and its fine, apart from the 8hr battery life.

dgstewart

I use the Forerunner 305 on the bike all the time and it's fine. Often thought about a "cycling specific" Garmin, but really can't justify the cost for something that will not do anything useful compared with the 305 (not interested in mapping as I usually know where I am going!).

I mount mine on the bars using the Garmin mount (http://www.heartratemonitor.co.uk/garmi ... ories.html). OK, it's not quite as sleek as the Edge type models, but it does the job fine. As with any GPS device, instantaneous speed will never be spot on due to update lag time, however average speed is very good. I've tested mine in the car and it agreed with car distance (and hence ave speed) to with 0.1 mile over 150 miles, which seems prety good.

Elevation measurement can be a bit variable though, as you often get elevation "noise", where there are lots of little false up and downs recorded that all accumulate over a ride to over-estimate total ascent and descent. This varies a lot from day to day and not sure why - maybe weather? For example, I have a regular short but hilly ride I do over 26 miles, and the total ascent has varied from 740m to 1050m. Most are around 800m to 850m, but there are several of these "outliers". It does make it a pain if you do a big ride as a one off as you can't really trust the total ascent. I guess this is where the barometric altimeter in some models would help, but then what happens when a weather front passes through?

moscowflyer

Thanks to the generosity of derbygrimpeur, I now have a Cateye computer to test it against, so will use the two in tandem to see how they match up.

turbo_hamster

I use my FR305 all the time for running and cycling. I would hate to be without it.

It sometimes produced absurd maximum speeds: 200mph+ . This appeared as a spike lasting only a few seconds, so I don't think it had much impact on my average speeds.

To be fair, it hasn't happened in a long time, since I updated the software.

c0ugars

I have a forerunner 305 which ive just started using on my bike, but i still have a cateye computer on my bike set up, and the read outs are the same, the current speed, average speed and max speed are the same a few times they have been 0.2 out, but i guess everything can be perfect.

derbygrimpeur

GPS accuracy varies and as such it is incredibly unlikely that a GPS unit can provide equal/better accuracy than a properly calibrated cycling computer. This is not to say that they're useless, but having used a GPS (Garmin Forerunner 110) and cycling computer at the same time I know for myself that they aren't totally accurate when you get to the point of wanting to know speed to within 0.5mph for example, or total distance within 1-2 miles.

Think about it logically, a GPS unit is relying on something in Space rather than a wheel connected to the Earth.

meanredspider

derbygrimpeur wrote:

Think about it logically, a GPS unit is relying on something in Space rather than a wheel connected to the Earth.

LMAO - that's the funniest thing I've read in a long time.

The thing in space can measure your location to within a metre. On my 305 mapped properly, I can even see which side of the road I was on. Where it has its greatest limitation is in elevation because of triangulation from satellites is limited. That said, every Munro I've climbed the Garmin, at the summit (with the best view of the sky) has been within a metre of the true elevation. Given that your average wheel-based bike computer has no idea of elevation, that's a small compromise.

I measure the same commute daily and get the same distance daily. Suggests the system is at least repeatable and, most likely, accurate. A wheel-based system will be subject to wheelspin (esp on an MTB), tyre deflection etc too. And, with the addition of the cadence sensor/wheel sensor for the Garmin at 31 quid you get the best of both worlds.

Honestly, I really can't see why you'd need any better than the accuracy the 305 gives.

derbygrimpeur

The accuracy of GPS varies depending on signal strength etc. Some of the units display the accuracy (my Edge 800 does, maybe the forerunner 305 does?) Garmin themselves say they're about 99% accurate. Which is fine and good enough for most people. But as I said, if you're wanting to fine tune things, a cycle computer is a better bet (even though that has it's own limitations).

I know from running with a Forerunner 110 that it will measure a different distance around the same route (taking the same line) virtually every time I run it. This is magnified the longer the distance. This is magnifiied even more on a bike to due rides being longer than runs.

Fair enough if you're happy using GPS, but it isn't as accurate as a cycle computer. That's why running course measurement still uses a bike, rather than GPS.

FWIW, I have both as I have a Garmin Edge 800 with speed/cadence sensor. I'm in no way anti-GPS.

moscowflyer

c0ugars wrote:

I have a forerunner 305 which ive just started using on my bike, but i still have a cateye computer on my bike set up, and the read outs are the same, the current speed, average speed and max speed are the same a few times they have been 0.2 out, but i guess everything can be perfect.

This is what I've found so far, other than max speed. Actual distance has been the same every ride though.