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Posted: Tue Mar 06, 2007 9:00 am
by mikesbytes
MichaelB wrote:Well, based on what Bikely mentioned, I got eager and corrected my bike computer wheel size (2.7% high) and did my "Morning Flat Run" training ride this morning, nad the comp now reckons that it is 29.06km, whereas bikely thinks it is 29.2km, so based on that, I think it is accurate now !!

Within 0.5% - much better but of course the speed is now lower ..., but having learnt the importance of cadence, am now focussing on that !!

Cheers

Michael B


Your doing yourself out of 140 mtrs

Burn plenty of Glycogen
training log
ImageImageImage

Posted: Tue Mar 06, 2007 9:20 am
by LuckyPierre
MichaelB wrote:Well, based on what Bikely mentioned, I got eager and corrected my bike computer wheel size (2.7% high) and did my "Morning Flat Run" training ride this morning, nad the comp now reckons that it is 29.06km, whereas bikely thinks it is 29.2km, so based on that, I think it is accurate now !!

Bikely is very susceptible to variation in ride length depending on how accurately you draw your map (the same goes for the route profile too). If you've adjusted your computer to more accurately match your tyre size or measured your actual wheel circumference, then that's good, but I don't think that you should use a setting on your computer that makes its distance function match a bikely-measured route distance. There was 3.8km (almost 5%) difference between the 'bikely length' and my computer's distance of my Sunday ride.
ps. I think that we have invented a new set of measurement units - 'bikely length', 'bikely-measured' etc. :)

Posted: Tue Mar 06, 2007 9:28 am
by MichaelB
Granted, but i measured the wheel travel properly this time (for one revolution with me on it) rather than the figure in the book, so I now have much more confidence in the figures being generated.

The route that I compared it with is 99.8% all straight roads, so I think that the accuracy of bikely is a good guide (good as I'm going to get) anyway.

Looking forward to Shepherds Hill road - only 25.4km, but a HUGE climb :shock:

Posted: Tue Mar 06, 2007 10:16 am
by LuckyPierre
MichaelB wrote:Granted, but i measured the wheel travel properly this time (for one revolution with me on it)

That's what I was hoping!
MichaelB wrote:The route that I compared it with is 99.8% all straight roads, so I think that the accuracy of bikely is a good guide

Even though I'm an ex-pat South Australian and lived in Adelaide a fair bit (in Wayville) and my Mum lives near Richard, I do forget about straight roads. :?
MichaelB wrote:Looking forward to Shepherds Hill road - only 25.4km, but a HUGE climb :shock:

Go for it! The thread on 'big chain ring climbing' has some contrasting ideas. Dare I say it, but grinding up a hill isn't good for you, so use your gearing to maintain a comfortable cadence and hope that your gearing is wide enough - then stand when you have too, pant when you have to and if that doesn't do it, bl**dy well walk! I still remember my first time up the climb out of Lower Molonglolo, when I did all of the above!

Posted: Tue Mar 06, 2007 10:30 am
by europa
Don't get too excited about bikely distances - they are going to be dodgy for all sorts of reasons. Set your wheel rollout as carefully as you can and leave it at that, treat bikely as an interesting anomoly and a useful tool for planning your trips.

Years ago, I compared a measuring wheel with a steel tape over 100m. Just casually walking the length easily resulted in errors on the wheel of over 10% simply because the operator wasn't following a perfectly straight line (ie, very small wobbles add a lot). Being very careful not to deviate from the straight line proved the wheel was accurate.

So, when you consider that bikely distances are going to contain errors, when you also consider that you are unlikely to ride a perfectly straight line between two points, you are unlikely to get the two to agree.

And don't get me started on the 'accuracy' of gps.

Richard

Posted: Tue Mar 06, 2007 10:39 am
by MichaelB
LuckyPierre wrote:
MichaelB wrote:The route that I compared it with is 99.8% all straight roads, so I think that the accuracy of bikely is a good guide

Even though I'm an ex-pat South Australian and lived in Adelaide a fair bit (in Wayville)


Snap. Just next to Goodwood oval is our abode !!!!

I'll let you know how the climb went on Tuesday. :roll:

GPS is ACCURATE !!!!!!! 8)

Posted: Tue Mar 06, 2007 12:07 pm
by LuckyPierre
MichaelB wrote: ... next to Goodwood oval is our abode ...

I realised that you had to be reasonably near my old house (it was the corner of Joslin Street and Rose Terrace). I used to run some of both your routes, but I mainly headed around the parklands, Victoria Park, the Zoo and places further north.

Posted: Tue Mar 06, 2007 12:20 pm
by MichaelB
Will start trying some different routes soon, but main thing is to avoid the traffic lights and traffic volume. Typically the weekday rides start prior to 0500 (to quote Robin Williams - "What does the '0' stand for ? "Oh my god it's early").

Will use Bikely to give me a good guide to distance and time.