My motor/controller is restricted to 2 speeds: low speed/high torque and high speed/low torque. I mainly use high speed/low torque

Thats interesting.. If this two speed are the max torque and max efficiency will be great!

As you can see in stoke monkey official website this is the "sweet" zone , where you want to operate you motor ( the curves for tonxgin may be little different but the concept is the same)

http://clevercycles.com/blog/images/powereffsweet.png

 

Clever Cycles » Blog Archive » Motors and bicycles

 

i will contact tongxing to see how the controller can work.

i think the best way will be a pedelec sensor combine with a throttle that remain in the position you set it. That combine with a rpm computer (as you are planing) so you can tune it.

 

On the other hand if you set correctly your sprocket / chainring so your usual cadence meets the RPM of the motor on the sweet zone, you haven't got to control to much your throtle, isn`t it?

Yes. My hub came off my 700c wheeled Cannondale. My sprocket has 16 teeth and the chainring has 32 teeth. The controller came off the Cannondale and I think the supplier (Cytronex) may have made some modifications.

You've got a Street Machine! ... Cool .. Nice one ... Are you going to Stoke Monkey it?

 

Sorry Steele I made a mistake. My chainring has 36 teeth.

... On the other hand if you set correctly your sprocket / chainring so your usual cadence meets the RPM of the motor on the sweet zone, you haven't got to control to much your throtle, isn`t it?

Yes. Thats what I think I'm doing. WHen I fit my cadence computer I hope I can confirm this! ..

You can do it with any bike computer.

Ok. I have installed my cateye and programmed my computer with TWO circumferences. One that Flecc suggested (1524) and one suggest (1670) at the following link:

63xc.com--How To | Cadence

The results with the rear wheel raised in the kitchen:

Cirumference, Slow Speed, High Speed

1670, 175, 212

1524, 160, 192

 

As my motor is rated at 175 rpm guess the top figures are correct.

Hi Steel, Just found a photo showing the specifications of my Tongxin:

[ATTACH]3207.vB[/ATTACH]

Yes. Thats what I think I'm doing. WHen I fit my cadence computer I hope I can confirm this! ..

 

Having some teething trouble. My "cadence" computer is wireless and was not positioned correctly or securely! ...will sort it out in time for the return trip. Here are my photos:

[ATTACH]3212.vB[/ATTACH]

 

[ATTACH]3211.vB[/ATTACH]

Having some teething trouble. My "cadence" computer is wireless and was not positioned correctly or securely! ...will sort it out in time for the return trip....

This is much better:

[ATTACH]3217.vB[/ATTACH]

I found having a rpm computer most useful. It confirmed what I had hoped. It also helps to focus and hit the "sweet spot" . During the ride home it seemed I was mainly in the range 160 - 190 rpm. As my gear ratio is 1:2 then that equates to cadence of between 80 - 95. At the end of my ride (which was only 8 miles due to my main chain snapping) my average rpms was 160 and my max rpms 267 which I find a little surprising as the highest I noticed while riding was about 210 rpms ... I may need to get the camera on the computer and get the evidence ...

This is much better:

[ATTACH]3217[/ATTACH]

I found having a rpm computer most useful. It confirmed what I had hoped. It also helps to focus and hit the "sweet spot" . During the ride home it seemed I was mainly in the range 160 - 190 rpm. As my gear ratio is 1:2 then that equates to cadence of between 80 - 95. At the end of my ride (which was only 8 miles due to my main chain snapping) my average rpms was 160 and my max rpms 267 which I find a little surprising as the highest I noticed while riding was about 210 rpms ... I may need to get the camera on the computer and get the evidence ...

You could get a very accurate measurement of your cadence from the camera. All you need to do is count how many times your foot goes round every minute. That's much easier to do after the event from a video than iy it is while riding. Sometimes I measure my cadence from my bike computer clock while I'm pedalling at a steady rate. As soon as the minute changes, I count until it changes again. It's nearly always 70 +/- 2.

Having some teething trouble. My "cadence" computer is wireless and was not positioned correctly or securely! ...will sort it out in time for the return trip. Here are my photos:

 

Nice set up! Regarding your max rpm, could it be that during a short acceleration you get a "peak" value for rpm which is giving an unreal value for rpm? I am guessing...

 

 

I have talking with tongxin sells and they told me you can get a pedal sensor + throttle or pedal sensor + display with buttons.

With the throttle there is an "auto" function available so after 8 seconds enters in autopilot and you don have to hang the throttle anymore.

The display with buttons shows the battery status and you can set the speed to 6 different positions.

I think the display is the better option. ( Also with brake sensor to stop the motor if you are braking)

 

 

 

Pd. I am getting used to pedal with the recumbent , at first my legs "hurt" when I climbed.. but everyday is better, i am improving...

At the end of my ride (which was only 8 miles due to my main chain snapping) my average rpms was 160 and my max rpms 267 which I find a little surprising as the highest I noticed while riding was about 210 rpms.

 

The 1524 circumference setting I calculated should be correct and the 175 rpm nominal of the motor falls almost exactly centre of the 160, 192 you showed for that setting. The 1670 you adopted is possibly the reason for your high reading, since it's way above what calculation indicates is necessary.

The 1524 circumference setting I calculated should be correct and the 175 rpm nominal of the motor falls almost exactly centre of the 160, 192 you showed for that setting. The 1670 you adopted is possibly the reason for your high reading, since it's way above what calculation indicates is necessary.

How did you get 1524 flecc? Is this speed formula not applicable: (circ x rpm x 60)/100,000 = kph

From my original post:

 

The 20" wheel computer setting is 62.8" circumference, then divided by 60 = 1.047

 

That gives an rpm reading just 4.5% high.

 

If you use the millimetre wheel size setting in the computer instead of 20", you can fine tune out that 4.5%

 

A setting of 1524 mm will give perfect accuracy, so get as close to that as the computer permits, maybe 1525 mm is a setting step.

 

You can see that if the 20" is converted to millimetres ( x 25.4) it's just over 1595. So I just took the 4.5% excess from that to get the 1524.

From my original post:

 

The 20" wheel computer setting is 62.8" circumference, then divided by 60 = 1.047

 

That gives an rpm reading just 4.5% high.

 

If you use the millimetre wheel size setting in the computer instead of 20", you can fine tune out that 4.5%

 

A setting of 1524 mm will give perfect accuracy, so get as close to that as the computer permits, maybe 1525 mm is a setting step.

 

You can see that if the 20" is converted to millimetres ( x 25.4) it's just over 1595. So I just took the 4.5% excess from that to get the 1524.

 

So. In my "maths" brain I have now installed the following:

Formula is: CIRC/60 = RPM where CIRC is in inches

Top get RPM =1 we need CIRC = 60 inches which when converted to mm is (60 * 25.4) = 1524 mm

Yes, that's exactly as I did it, just getting equality of the 60 each side to get that 1.

Ok. I have installed my cateye and programmed my computer with TWO circumferences. One that Flecc suggested (1524) and one suggest (1670) at the following link:

63xc.com--How To | Cadence

The results with the rear wheel raised in the kitchen:

Cirumference, Slow Speed, High Speed

1670, 175, 212

1524, 160, 192

 

As my motor is rated at 175 rpm guess the top figures are correct.

 

Ok. I took the advise of d8aveh and put a bright yellow spot on the hub, shot a min or so of footage and played it back in slow motion I used slow speed mode and counted 170 ... Doing the high speed test next ..

High speed = 202 ..

Edited February 19, 201214 yr by kitchenman

Dead in the middle of your two previous figures, there's diplomacy for you!

Dead in the middle of your two previous figures, there's diplomacy for you!

What? lol ... your going to have to formulate that mathematical analysis for me (again! ) ... I'd say its nearly in the middle. ... or is it malcolm in the middle! ... (looking round for the lunchtime sherry so you'd better be quick cause in about 2 mins this is all going to get even more hazy) ...

Dead in the middle of the high speed figures for the two settings, I ignored the low speed ones!

 

I still maintain my 1524 is correct for accurate readout though.

Dead in the middle of the high speed figures for the two settings, I ignored the low speed ones!

 

I still maintain my 1524 is correct for accurate readout though.

All very well maintaining. Wheres your evidence? .. Here's mine:

 

Notice the chain movement? ... Thats probably not a good thing .. Umm.. .

Edited February 19, 201214 yr by kitchenman

My evidence is only in the maths balance, equalising the sides of the equation to reach one to one readout from the pulses. If the cycle computer is doing it's job, that 1524 setting should give an accurate count of revs per minute. Any other setting will give either higher or lower readings than the actual revs per minute.

 

It wouldn't surprise me if the computer readout isn't accurate, I notice 10mph uses a mechanical counter for his marathon course ride distance checking to ensure absolute accuracy, rather than trusting to electronics.

Alan, I take my hat off to you sir. That motor arrangement is brilliant. i never thought it would come out so good,

My evidence is only in the maths balance, equalising the sides of the equation to reach one to one readout from the pulses. If the cycle computer is doing it's job, that 1524 setting should give an accurate count of revs per minute. Any other setting will give either higher or lower readings than the actual revs per minute.

 

It wouldn't surprise me if the computer readout isn't accurate, I notice 10mph uses a mechanical counter for his marathon course ride distance checking to ensure absolute accuracy, rather than trusting to electronics.

I think that must be it. Would be interesting to try different computers and see how they vary ..including a pure cadence computer .. anyway, based on my video results I have now entered 1621 which I think is probably giving me a more accurate reading. This mornings average was 160 rpm with a max of 233 rpm ..

Alan, I take my hat off to you sir. That motor arrangement is brilliant. i never thought it would come out so good,

Thanks Dave. I am really pleased with the results I am getting and there are still things that need refining so there is always something to think about.. No freewheel, no brake sensor! , battery housing could be better not to mention messing about with fairings, canopies and cameras ....

Pd. I am getting used to pedal with the recumbent , at first my legs "hurt" when I climbed.. but everyday is better, i am improving...

Steele, I would recommend getting a cadence computer. This will really help you with your hill climbing. With correct gear changing and the right cadence (for you) your legs should not hurt at all. I am "born again" having fitted my cadence computer. If I want my legs to hurt then I can simply change gear now. i.e I am in control of the bike. Its not in control of me! ...

Also, Do you have a head rest on your seat? If not, I would recommend getting one. If you find yourself having to push the bike for any reason it really is very useful. The balance of the bike is such that you can do this:

 

Edited February 21, 201214 yr by kitchenman

Ok. I took the advise of d8aveh and put a bright yellow spot on the hub, shot a min or so of footage and played it back in slow motion I used slow speed mode and counted 170 ... Doing the high speed test next ..

High speed = 202 ..

Based on the videos I worked out that I would need to enter 1621 as the circumference which is what I have been using for the last few rides. However, I realised that I had not checked this by raising the back wheel. I've just done that and 1621 produced a result of 161 and 194. Through trial and error I have now set the circumference to 1730 which is giving me a result of 170 and 205 which is pretty close to my video rpms. ...