Average Speed - do you believe it???

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Average Speed - do you believe it???

Postby drevil » Tue May 22, 2007 8:34 am

I have noticed my Sigma 10 function (or there abouts) computer always shows an average speed of about 21/22 kmh, regardless of what I ride.

The other day I went for a ride with 2 mates and they reset their avarage speeds and they showed 23 & 24kmh respectively. I kept up with them and didn't seem to be riding any harder than usual.

So, yesterday I went for a ride with a different friend. I reset the av speed and we hit it hard (well, for me anyway). Every time I checked we were doing 28-31kmh, but guess what? I checked average speed halfway through the ride and it was 21.7kmh!

What the??? There were not many slow bits or up hills at that point, so I don't know if it's worth anything. The rest of the compouter is accurate, so I don't know.

What's everyone else's experience?
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by BNA » Tue May 22, 2007 8:43 am

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Postby Bnej » Tue May 22, 2007 8:43 am

I go from 20 to 25 at the moment. I got 26.6 for the Blaney to Bathurst. I find that on shorter rides, slowing down and stopping, giving way, etc, has a big impact.

I have to ride up a lot of hills where I live, and they kill the average speed - you never get as much back on the downhill as you lost on the up.

You could check distance and ride time and try calculating the average from that.
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Postby sogood » Tue May 22, 2007 9:01 am

What kind of unit? Wireless or wired? If it's wireless, then you might care to consider replacing the batteries. If it's wired, then check the magnet and sensor separation distance.
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Postby drevil » Tue May 22, 2007 9:45 am

What kind of unit? Wireless or wired? If it's wireless, then you might care to consider replacing the batteries. If it's wired, then check the magnet and sensor separation distance.


It's wired. The magnet distance seems OK, and I guess problems with the gap would show with the current speed and odometer readings, which always work without fault.

I assume average speed works on moving time, not total time, so stopping should really affect it, but going slow will.
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Postby Hotdog » Tue May 22, 2007 10:08 am

Bnej wrote:You could check distance and ride time and try calculating the average from that.

This. The recorded trip distance divided by the ride time should agree with the average speed reading, provided you reset all of them at the start of the ride. If it doesn't then you must have a faulty cycle computer.

I've got a Sigma BC 1600 (wired, about 10 functions, similar to yours) and the average speed seems to work fine, ranging from low 20s up to around 30 depending on the ride.
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Postby MichaelB » Tue May 22, 2007 10:55 am

drevil wrote: [average speed works on moving time, not total time.


Correct.

I too have a Sigma 1606 and have no problems.
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Postby Kev365428 » Tue May 22, 2007 12:59 pm

Easy way to check -

1. Ride for 10 minutes exactly
2. Multiply the distance travelled by 6
3. Check this figure against your computer.

Do this on a flat where you know you'll be above 25km/h if your still wary about the 21-22km/h figure on the computer.

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Postby europa » Tue May 22, 2007 1:04 pm

drevil, when I get the space, I'm regularly riding at over 25 km/hr and often over 30. My averages are always down around the 21 mark. Why? Because any slowing of your speed (corners, cars, lights, tiredness) pulls that average down very quickly. Some computers have the option to show your average as you ride, and it's scary to see it wind backwards sometimes. To get a high average, you have to not only ride at those speeds but to maintain them - on anything but straight, uninterupted runs, that's just not going to happen.

The numbers game is a cruel one.

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Postby moosterbounce » Tue May 22, 2007 1:12 pm

It always amazes me how quickly your average speed can come down, yet it takes ages for it to go up again!! It just doesn't seem fair :?

You are right...the numbers game is a cruel one.

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Postby MJF » Tue May 22, 2007 2:21 pm

I have a Sigma 1606L... and I've caught it out once where it gave the wrong average. I only picked it up because my trip from the previous day was only a few seconds differen, but the Avg speed was out by more than 1km/h. I checked a weeks worth, but only the one trip was incorrect.
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Postby Noids » Tue May 22, 2007 9:12 pm

Try having your average speed visible and keep an eye on it during the ride. I've got a 1606 wireless sigma. I notice that if I stop however, the average speed stops changing even though the trip timer is still counting away, so your distance travelled/trip time will not necessarily correlate exactly with you're average trip speed. The difference would be a faster average speed though, so not the effect you're seeing :P

I think the others hit the nail on the head, basically you underestimate the amount of time you are slowing for various reasons. I know on Sundays when there are lots of walkers out my ave. speed is a lot slower than early morning runs mid week even though I feel like I am pushing about as hard (all that extra accelerating I guess :P).

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Postby JackHenry » Tue May 22, 2007 9:50 pm

On the 1606, the trip timer only works while the bike is moving. It stops when you do.
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Postby Noids » Wed May 23, 2007 10:42 pm

Ahh fair enough that would explain it. Getting confused with the stopwatch function that I also use on the rides :P
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