Hill Climb maths ?

flecc · Feb 26, 2008

That's exactly right.

Then if you divide 100 by that 23.205, you get 4.3, so its a 4.3% hill, or just rounded to 4%.

That's actually a very gentle slope, 2% variations generally regarded as flat.

Any throttle controlled e-bike would sail up that with ease at not much less than the flat speed, and on a Panasonic unit bike the standard power mode would be plenty.
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flecc · Feb 26, 2008

I don't know. I often find the software methods more long winded where single stage basic calculations are concerned.

I just rough it out in the mind like this. Take what you posted:

"Im climbing a hill at 195 feet high. whilst covering a distance to the top of that hill of 4,525 feet."

I just round the 195 up to 200, apply a similarly small addition to the 4525, making that about 4600 to round that as well.

Then I calculate on that, 200 into 4600. We can lose the pairs of zeros, so it's just 2 into 46, which is 23.

You can see thats exactly the 1 in 23 you arrived at, done quickly by just simplifying the initial numbers which proves quite accurate enough for a quick answer. No-one expresses hills in X number of decimal places, just the whole number near enough.

Explanations like this are long winded, but what I described can take place instantly in the mind.
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flecc · Feb 26, 2008

You are actually quite fit judging from that walking, compared with large numbers of your age these days.

I have a route very similar to that near me and I have times for that on an Agattu. Based on that the trip would take about 26 minutes with standard mode power and my 70 kilos at 72 years of age.

Adjusted for the lighter Pro-Connect and your younger age, but offset by your own higher weight than mine, I think you'd beat that time quite easily.

However, the differences are not large. Quite a lot of effort is necessary to increase an average speed by 1 mph, and that would reduce the 26 minutes to 24 minutes, so you can see that estimate of your journey time will be fairly close.

Using high power mode all the time will increase the average speed by half a mile an hour, reducing the 26 minutes to 25, and the 24 minutes to 23. That small gain wouldn't be worthwhile as it stresses the transmission more and could mean overheating the power unit when in continuous high power mode on hot summer days.

You should be able to do the return journey in about 16 minutes if you leave the brakes alone.

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flecc · Feb 26, 2008

burncycle said:
PS seen the new Kalkhoff Flecc ?

Do you mean the Pro-Connect?

I haven't seen that in the flesh, only on the website photos.
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keithhazel · Feb 26, 2008

burncycle said:
OK. Got my figures really hammerd down now on my cummute to work.

I can walk a 1 in 7 with a 30lbs rucksack on my back for 6miles in 3 hours.

------------------------------------------------------------------------
thats unlucky to live near a 6 mile road thats 1 in 7.........ok if you live at the bottom...

flecc · Feb 26, 2008

Thanks, I hadn't seen that.

Very nice, and Magura hydraulic brakes are the tops.

But although I could afford either with ease, I'd stick with the standard Agattu for three reasons:

1) It's brakes are already superb as I said in my review.

2) There's already more than enough gears on the 7 speed, and 8 is overkill when the top gear is always related to 15 mph top assisted speed, so any extra gears just go lower and lower.

3) The extra £245 almost buys a second battery for rides up to 100 miles.

Many will always want the best regardless of course, and they certainly wouldn't be wasting their money on a product like that.
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BossBob · Feb 28, 2008

based on a journey of 5 miles ...... using a pedelec with a top assisted speed of 15 miles and hour ...... and you intend to assist it (just a little it wont need a lot)

Your journey time will be ........ 20mins
or just a shade under depending on how much you assist

flecc · Feb 28, 2008

It depends on the terrain BossBob. On an almost the same 4.9 miles, rising some 480 feet over the distance, the Agattu and I recorded 26 minutes on mixed power modes and 25 minutes on high power mode only.

In more flat conditions I rode assisting the bike at a 13 mph average comfortably, so the 4.9 miles would take about 23 minutes at that.

A to B recorded about 12.5 mph average speeds, and their David is a very powerful cyclist, and from my years with a Lafree Twist I'd say that 12.5 mph is about par for these Panasonic unit bikes. A 15mph average could only come from the cyclist doing just about everything, and in general only the odd powerful hub motor bikes like the eZee models average 15 mph. On my Q bike, (geared Quando which uses the Torq motor) I average 15.3 mph around my area, but thats a very powerful 576 watt motor.

Remember the Panasonic unit rarely exceeds 300 watts and sticks closely to European law in phasing down power from around 12 mph, so assistance is all gone by 15 mph.
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Caractacus Potts · Mar 1, 2008

hypotenuse or side ?

burncycle said:
Still trying to sort out my hill climb rating for my cycle to work.
Just to clarify my maths on this issue !

Im climbing a hill at 195 feet high. whilst covering a distance to the top of that hill of 4,525 feet.

Ive got 4,525/195 = 23.205.

So the hill is a 1 in 23.

Hope thats right !

flecc said:
That's exactly right.

Then if you divide 100 by that 23.205, you get 4.3, so its a 4.3% hill, or just rounded to 4%. ...
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Flecc,

In the past you have suggested taking a metre long rule and attaching a vertical measure to determine the slope as a percentage, this method measures the horizontal distance travelled in relation to the vertical distance to determine the slope as a percentage(i.e. the two sides of the triangle at right angles to each other).
However in the quotes above, Burncycle suggests taking the road distance travelled (i.e. hypotenuse of the triangle) and you say that this method also gives the correct answer.

Both methods can't be right

- which is correct ?

OK in most cases it won't make that much of a difference but in the extreme, if you had a 1 in 1 hill (I know an ebike wouldn't get up that but it makes the sums easy

), the road distance (hypotenuse) would be 1.4 times longer than the horizontal distance giving a 40% error.

flecc · Mar 1, 2008

This issue crops up every time I comment on hill climb measuring John, and I'm sure you'll agree that it's somewhat pedantic.

My advice is always given in terms of practical accuracy. While I appreciate and use theory, it always takes second place to the real world situation. Here's the reply I've given previously to the contention that the hypotenuse is correct:

"To give some idea of the size of the error using "stick and rule", a 12% will actually be an 11.91457%, a 7% will actually be 6.98291%, so you can see why I don't think the difference is worth bothering with. Even a 20% will only vary slightly, the correct gradient being 19.611688%. Not relevant for us I think."

In fact I understand that there is disagreement in the mapmaking and surveying world on what matters, surveying I believe using the hypotenuse as the linear element for calculation.
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Caractacus Potts · Mar 2, 2008

Flecc,

Thanks for the clarification, I wasn't aware of the disagreement between the professional bodies. The reason behind my 'pedanticism' is that there is a local hill near me that was signed as a 1 in 4 (and I could get up it in my youth) but, looking at the road on memory map, I can't get the gradient more than 1 in 6 at its steepest point so I was looking for an explanation. That way I can use memory map to predict the gradient of hills on planned rides (in my 'not so' youth).

flecc · Mar 2, 2008

Only teasing on the "pedantic" John.

That is quite a hill, only a few on British roads steeper than 1 in 5 (20%). I have a couple of short bits steeper, a 1 in 4.5 and a brief 1 in 3.3, the latter just manageable with the aid of a heavily modified eZee Quando, but not on any standard e-bike.
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Ian · Mar 2, 2008

Caractacus Potts said:
Flecc,

Thanks for the clarification, I wasn't aware of the disagreement between the professional bodies. The reason behind my 'pedanticism' is that there is a local hill near me that was signed as a 1 in 4 (and I could get up it in my youth) but, looking at the road on memory map, I can't get the gradient more than 1 in 6 at its steepest point so I was looking for an explanation. That way I can use memory map to predict the gradient of hills on planned rides (in my 'not so' youth).

Memory Map and other 3D mapping software is based on known survey points that in most cases are actually tens of meters apart vertically and hundreds of meters apart horizontally. The software calculates the position and elevation of all other points from theses points so in reality it can only give an average figure for hills between its known points. In contrast it is the gradient at the steepest point that is quoted on signs and as few hills are constant you hill may well have a maximum of 1:4 with an average of 1:6.

Another error commonly occurs with 3D mapping software when a road clings to a hillside where a very small error in the road position will make a large difference to it's vertical position, accuracy not being helped by the fact that in 1:50000 mapping even minor roads are represented as being a scale 50m wide, necessary to make them visible of course.

Hill Climb maths ?

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