Route measurement

Mr Magners

Looking for a bit of guidance.

I'm only new to cycling and I'm not in a position to buy a Garmin or any of those GPS units so I'm relying on a basic cycle computer and a combination of different websites to tell me how far I've cycled. I'm getting different results all over the place with the cycle computer constantly reading higher than the web based map systems.

My question is what's the best one to use for accuracy? I also have a Blackberry onto which I downloaded "Greattrainer" but that never seems able to pick up satellites. Does anyone know of an alternative to that app that I could use.

Thanks for reading.

Pherekydes

If your computer is consistently reading high then maybe you have it set up incorrectly.

There's probably a setting in there somewhere for wheel diameter. Check and adjust.

Beasty

Before moving to GPS I found that over a 23km commute the distance could vary by up to 300m - I eventually sussed out that I was travelling "further" if my tyres were not fully inflated (and that difference was down to the tyre pressure varying between about 80 and 120psi)! I keep them fully inflated now;)

It is important to measure wheel circumference properly, basically rolling it along the ground for a full revolution with rider fully on the bike, as wheel and tyre combinations can make a big difference to standard sized wheels

Mr Magners

OK, maybe I haven't set up the comp properly, I'll have to have another go at it this evening.

Are the on-line maps pretty accurate though?

Thanks again.

smacl

It's also worth remembering that bike computers using a magnetic sensor are measuring the distance the wheel travels, which is slope distance, whereas on a map you are measuring plan distance which will be shorter on steep gradients. You also don't travel in an exact straight line along the road on a bike, so the length of the line you travel, as measured by the bike computer, will be a bit longer than the straight line connecting the end points of the road. e.g. if you pass an obstacle such as a parked car, swerve to avoid an irate bus driver etc.. this all adds to the distance travelled.

Plan distance, as measured on a map, should always be shorter than distance travelled, if it is not, your bike computer is not set-up properly.

Surveyor11

If you have an android phone, I find the (free) "imapmyride" app great. It gives all sort of detail back on rides - distance covered, gradients, max speed etc. All based on google maps data, so pretty accurate (in my book anyway!).

I have found it to tally pretty well with my basic cateye cycle computer in terms of distance covered - but the cateye doesn't measure time stopped (for instance). Didn't really cop that inflating the wheels would have such an impact.