Bike speedo v GPS

General cycling advice ( NOT technical ! )
andrec
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Re: Bike speedo v GPS

Postby andrec » 3 Jul 2019, 7:12pm

Advantages of a speedo are that you can get one very cheaply and the battery lasts for about 3 years. I've just bought one for £8 from Wilkinsons to replace a Decathlon one I'd had for about 10 years which suddenly refused to work. I am only interested in having a speedometer, a trip meter and an odometer.

Grandad
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Re: Bike speedo v GPS

Postby Grandad » 3 Jul 2019, 11:04pm

. I am only interested in having a speedometer, a trip meter and an odometer.


I have the same limited needs and also use a Wilko computer. Only snag is that there is no option to calibrate it using the distance covered by one revolution of the wheel - just a choice of specified wheel sizes. Can't find any other computer with this feature currently on sale.

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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 4 Jul 2019, 7:23am

That is why I bought a very basic Garmin Edge 20.
https://buy.garmin.com/en-GB/GB/p/508487
You can find them cheaper if you search.

I use it for logging my rides, odometer, trip meter, and speedometer.
I can follow a pre-loaded course, and have a virtual partner to try and keep up with, but I rarely use it.

It'll go for seven or eight hours on a single charge, and is small and neat and self contained. No wheel calibration, no wires, just a clip on the handlebars. You can even use it in a pocket and fish it out to look at from time to time if you don't want the clutter on the 'bars.
Mick F. Cornwall

francovendee
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Re: Bike speedo v GPS

Postby francovendee » 4 Jul 2019, 7:59am

Grandad wrote:
. I am only interested in having a speedometer, a trip meter and an odometer.


I have the same limited needs and also use a Wilko computer. Only snag is that there is no option to calibrate it using the distance covered by one revolution of the wheel - just a choice of specified wheel sizes. Can't find any other computer with this feature currently on sale.

That's really odd. I've had a number of cheap computers from places like Aldi and lidl and everyone of them had a way to use custom wheel settings. This weren't immediately obvious from the instructions.

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NATURAL ANKLING
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Re: Bike speedo v GPS

Postby NATURAL ANKLING » 4 Jul 2019, 9:28am

Hi,
Most of those cheap computers just use centimetre circumference inputs.
Well all the ones I've used have, are you saying the later ones just have wheel sizes only?
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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 4 Jul 2019, 2:04pm

NATURAL ANKLING wrote:Has anyone got the satnav to read longer than an online route planner?
Today, I had a short but vigorous ride.

My Garmin Montana said 17.51miles.
I connected up to my computer, and launched Ascent, my bike rides program.
Ascent smooths out perturbations generally and gets rid of the spikes. Ascent said 17.48miles
Plotting the exact route on BikeHikeUK, it said 17.45miles.

Difference?
Not much of only 0.06miles = 105yds.

Does it matter?
Mick F. Cornwall

andrec
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Re: Bike speedo v GPS

Postby andrec » 4 Jul 2019, 3:00pm

When I end my ride, put my bike back in the hall, take a note of the mileage and reset the trip meter to zero I resist the urge to look where the wheel magnet is to see how close I am to another click which might register another 100th of a mile or 17.6 yards.

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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 4 Jul 2019, 3:32pm

:D :D
One issue you can have with a wheel magnet system, is if you stop and lean your bike up as the magnet is right next to the sensor, it can register multiple revs.

Once, I was in Ludlow at a cafe and took my Cateye Mity8 off the bike to peruse the trip and ave speeds data over a cuppa.
The outside table was a brushed metal table and as I slid the Mity8 over to it get a closer look, it registered 200odd mph momentarily!
The bare contacts connected with the metal intermittently as it moved.
Mick F. Cornwall

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NATURAL ANKLING
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Re: Bike speedo v GPS

Postby NATURAL ANKLING » 4 Jul 2019, 6:38pm

Hi,
Mick F wrote:
NATURAL ANKLING wrote:Has anyone got the satnav to read longer than an online route planner?
Today, I had a short but vigorous ride.

My Garmin Montana said 17.51miles.
I connected up to my computer, and launched Ascent, my bike rides program.
Ascent smooths out perturbations generally and gets rid of the spikes. Ascent said 17.48miles
Plotting the exact route on BikeHikeUK, it said 17.45miles.

Difference?
Not much of only 0.06miles = 105yds.

Does it matter?

not bad, but you're using software to iron out the errors of the satnav.
Do satnav's read flat Earth or interpolate? Don't answer that, then they probably account for hills as well.
My satnav as I said earlier is .6 of a mile out over 36 miles, I think there is an option to gain more accuracy.
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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 5 Jul 2019, 9:03am

Forget the Ascent program issues.

Garmin Montana = 17.51miles
BikeHikeUK = 17.45miles.

Why the difference?
Mick F. Cornwall

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NATURAL ANKLING
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Re: Bike speedo v GPS

Postby NATURAL ANKLING » 5 Jul 2019, 9:17am

Hi,
Mick F wrote:Forget the Ascent program issues.

Garmin Montana = 17.51miles
BikeHikeUK = 17.45miles.

Why the difference?

You said yourself that software has modified your satnav result.
Oh I see what you mean sorry, I don't have an answer for that only to say that that error is minuscule.
Not on the scale of the poster or me sure.
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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 5 Jul 2019, 10:22am

Minuscule?
That's a matter of what you consider is minuscule I suppose. There's "only" a 1% error after all.

Planning a 1,000mile ride, you could be 10miles out even comparing online distance calculations and GPS.

Just think how far you could be out using a wheel magnet system. :shock:
Mick F. Cornwall

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NATURAL ANKLING
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Re: Bike speedo v GPS

Postby NATURAL ANKLING » 5 Jul 2019, 10:31am

hi,
I'll see what you mean. When I did a long ride say 100 miles, my Speedo was half a mile Too far, so I just adjusted the wheel and put to compensate.

But on individual satnavs, They have their own internal software, Online planners also have software, they are not using the same for sure.
If You Don't Try You Don't Do.....Don't Do You Don't Get...I'm Still Trying....Well Very..
You'll Find Me At The Top Of A Hill...............Somewhere...After Dark..

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The utility cyclist
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Re: Bike speedo v GPS

Postby The utility cyclist » 5 Jul 2019, 8:16pm

For the last few years I've started going on the 'fast' bike with neither, I don't need to know how fast I'm going and for the most part I know where I am (let's be honest it's pretty difficult to get lost in most of the UK and even then not for that long). door key and some money for a pint on the way back, I can't even be bothered to take the phone.
I actually find it much more enjoyable riding to how I feel as opposed to looking at any given number, I can ride as far as I feel like riding having an idea how far to get home visually not necessarily in actual distance, I can ride as hard or as gently as I want and not have the computer tell me I've gone x slower or faster than some other ride I did do with a measuring device.
For utility when you want to be somewhere for a certain time and you want to know how far it is so you can approximate arrival times at your particular pace, they can be a useful tool, but after that first time you'll know and the speedo/GPS becomes a bit redundant. For touring when you want to know how long before certain turns or stopping points/end destination and if not old school using the GPS to navigate they can be a godsend particularly in areas you're unfamiliar with. And obviously racing/training.

Otherwise for many trips you just don't need them.

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Mick F
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Re: Bike speedo v GPS

Postby Mick F » 6 Jul 2019, 9:09am

The utility cyclist wrote: ............ Otherwise for many trips you just don't need them.
Need.
That's the word.

I'm a bit obsessive, so I need to log where I've been and how far and when.
I've GPS records going back to 2007, and reconstructed ones from before back to 2004 when I got back into cycling after a few years off after leaving the RN.

I don't often follow a route, or even have a page showing any speed or any data. Sometimes I do, especially if I'm on a task or other, but as for stats whilst on the road, I rarely bother. I'm more interested in the maps.
Mick F. Cornwall