Torq owners: What is your top "motor-only" speed? (limited or delimited)

[coops]

Thanks, I'm reassured that at least the difference in top speed seems less than I first thought, and indeed may be entirely down to difficulties in getting an accurate reading, plus other variations due to battery type & temperature etc.

I also store bike & batteries indoors, but outdoors its not even room temp & certainly not summer temps yet!! In my experience battery performance is markedly decreased by lower temperatures as you say, and I can only guess that must be amplified for batteries this size: I am aware its not the best time to be checking on them, but I want to be fairly sure all is working as expected with the new bike - I'll wait & see what the warmer weather brings, and plan any gearing mod to allow for a modicum more speed

For now, less rain & more still,clear air please

Thanks again to all of you for your help & time.

Stuart.

 

[ITSPETEINIT]

How big is your wheel?

I hope Peter won't mind me observing that the wheel size he's given is almost certainly too big, and it may therefore be that his speedo is set high. He has given the diameter as 28.5", but my identical type of Kenda tyre isn't that size. It's circumference is 2231 mm, therefore a diameter of 710.5 mm which is 27.97". That means Peter's readings if his speedo is set to that 28.5" are 1.85% high.

Tyre wear comes into it as well, since as the tread wears down the speedo should really be reset for absolute accuracy to be achieved.

.

I must admit to having a problem with bending down so close to the ground without distorting my vision.
I have taken the measurements again and there are some tolerances to take into consideration:
Wheel Diameter: The 28.5 inches was as accurate a measurement as I could make using a standard metal tape.
To eliminate any parallax difference I made a giant caliper and re-measured the diameter. It was 28.3204 ins = 719.338 mm.
The theoretical circumference was thus 2259.867 mm
I measured the circumference of the tyre using a fabric tape. The measurement was 2260mm.

Of course this takes no account of a tyre distorted by the weight of the rider and probably describing a smaller circle (recommended by Avocet Cycle Computers) :

There is between us a difference of 9.188 mm (0.362 inch) on the diameter and 28.867mm on the circumference.
This is a difference between us of 1.29%
Your calculation of the percentage difference based upon my 2240 and your 2231 = 9mm would be 0.4%.

The ready setting calculator which came with the Velo 5 Computer unfortunately did not go quite high enough when recommending the setting to be used with a 700 x 45 tyre (47-622) - it gave up at 700 x 40C (40-522) which had a circumference of 2200 mm.
It seems I should recalibrate my computer to 2260

Peter

 

[flecc]

You definitely have a bigger tyre than me then Peter, a surprisingly big manufacturing tolerance, though tyres do vary between batches. Makes your bike faster of course, and I wonder if Stuart's tyre is at the other extreme, at the small end.

Like you I reported the actual diameter, making no allowance for compression.
.

 

[coops]

Brainwave: measuring wheel length

In the interests of a more accurate wheelsize for the Torq, I tried "rough" measurements & got anywhere between 223 & 226cm, but then I had a brainwave - its probably a standard way to measure these things, but hadn't occurred to me before & very simple (you could try this too Pete, if you like & if its not awkward for you, or anyone else for that matter):

Ok, for this you need a measuring device (tape measure, long ruler, etc. any will do), at least 2.23m or so of flat ground (you know what's coming now, don't you!) and something to mark a start and end point.

Using any point on the front wheel of the bike as a "marker", mark your start position with that point directly on the ground, then wheel the bike forward one wheel revolution till that point is again at the lowest point of the wheel & mark this end point on the ground.

The distance from start to end point is one (unloaded!) revolution of the wheel, or its circumference!

So my front wheel has around 223.7cm circumference, or ~71.2cm/28.03" diameter as best I can measure it: that's not significantly different from yours Flecc, but I didn't expect it to be .

As you say Flecc, I'd be surprised if there is much variation in this: it is difficult to measure the wheelsize any other way, so if you were to try this Pete, or anyone else, I'd be interested to see if you get a very different value .

Stuart.

 

[flecc]

You've re-invented it Stuart, that's many cycle computer manufacturer's recommended method, marked from tyre to ground.

If it's done only over one revolution it can still be inaccurate though, it needs three or so turns to get fairly accurate. I use my gradient device over the front tyre, bar levelled on it's spirit level on the tyre, then the tape drop to the ground gives the diameter exactly. Then I check the result and trim it finally over a known exact distance riding course.

This is the device I mean:

.

 

[coops]

Yes, good point re much better accuracy over several turns: I did one turn only, repeated a few times & averaged, due to lack of space, but still its not terribly easy to make an accurate measure, and lots of bending too, Pete!

Your tape & spirit level method looks much easier to use & more accurate too!! Now that's neat I guess I'll become a surveyor now, since it will double as a gradient measurer too!

Thanks for the tip: I'll try it again now, except on my Torq I'll need to remove mudguards to do it...

Stuart.

 

[ITSPETEINIT]

Oh Yeh!

In the interests of a more accurate wheelsize for the Torq, I tried "rough" measurements & got anywhere between 223 & 226cm, but then I had a brainwave - its probably a standard way to measure these things, but hadn't occurred to me before & very simple (you could try this too Pete, if you like & if its not awkward for you, or anyone else for that matter):

Ok, for this you need a measuring device (tape measure, long ruler, etc. any will do), at least 2.23m or so of flat ground (you know what's coming now, don't you!) and something to mark a start and end point.

Using any point on the front wheel of the bike as a "marker", mark your start position with that point directly on the ground, then wheel the bike forward one wheel revolution till that point is again at the lowest point of the wheel & mark this end point on the ground.

The distance from start to end point is one (unloaded!) revolution of the wheel, or its circumference!

So my front wheel has around 223.7cm circumference, or ~71.2cm/28.03" diameter as best I can measure it: that's not significantly different from yours Flecc, but I didn't expect it to be .

As you say Flecc, I'd be surprised if there is much variation in this: it is difficult to measure the wheelsize any other way, so if you were to try this Pete, or anyone else, I'd be interested to see if you get a very different value .

Stuart.

I tried it and when Flecc questioned my results (see above first posting) I tried it again. I wont tell you what either measurement was.
There is another way. Flecc has convinced me that measuring the diameter and/or the circumference will give the basis that a bit of Pi will finalise. You can have the answers in Millimeters (same figure for the Computer setting) or inches.
I made a GIANT CALLIPER. A piece of wood 4 inches wide, 3/4 inch thick and 34.5 inches long. Two other pieces of wood about 6 inches long x three inches wide were attached to the former precisely at right angles so that the gap between the two right angle pieces was 28.5 inches exactly. (I had measured my wheel across its diameter at the widest point on the circumference with a metal tape and found it to be 28.5 inches with + or - parallax. I had to cut a piece out of the centre of the long piece 2 inches wide by 2 inches deep: this is to accommodate the wheel nut and fork end which protrudes and allows the long piece of wood to rest on the hub motor either side of the fork. This steadies the calliper. Pressing the inside of one end on the tyre one then notes how far away from the other side of the tyre the other end is. If the calliper is not big enough you may have a funny 700 x 47 tyre that is not seated properly. Now, one does not guess at the size of the gap: one can measure it by slipping a piece of wood of the right thickness that fills the gap precisely (I have lots of pieces of ply, pine and formica from the many carpentry disasters that I have enjoyed over the years ). Measure the thickness of that wood You can do that very precisely if you have one of those digital callipers), and subtract that from 28.5 inches. The result you know is the diameter of the wheel/tyre.
From this I calculated the theoretical circumference of the tyre.
Now the PROOF!
I then laid a fabric tape (having checked it for stretch against a metal one) around the highest point of the tyre and noted the measurement.
The difference between the two measurements was less than 1 millimeter.
BUT it was very different from the two measures I had taken of the wheel having travelled over the paving fromn one mark to another.
Perhaps Flecc is right: one should revolve the wheel two maybe three times to minimize (or average) the error.
One would be lucky to have a flat area that long without flower pots, cold frames, steps, patio chairs, umbrella stands, and other garden debris.
Peter

 

[coops]

I found another variation (so you can have 4 different results ) but very easy and fits well with my other measurements: simply measure the radius from the base of wheel (on the ground) to mid-axle, as close as you can estimate; then double it to get the diameter: I got within 1mm of my previous measure of diameter .

Stuart.

 

[flecc]

simply measure the radius from the base of wheel (on the ground) to mid-axle, as close as you can estimate; then double it to get the diameter

Stuart.

And in a refinement of this, if a long arm set square is available, the short arm onto the tyre and the point of the spindle centre markd on the long arm will give the exact radius.