Dish or shim, what does the team think ?

[Old_Dave]

Afternoon all..

Build 2 is going remarkably fast, the cost was justified as a winter project to keep me amused until March... however it now looks like I won't be able to avoid finishing it by mid next week at the very very latest

A question arises however in what does the team think about the hub.

The rim with a rear Q100 has been built by BMS and is centred onto the hub rather than the axle, so choices are to either dish the rim or offset the hub between the dropouts.

Of course at this moment I'm preferring the simple offset option which will result in a very close but not perfect to the mm centre, but will bow to expert opinion if there are reasons why the longer option of dishing is preferable.

Pros and cons ?

 

[morphix]

Afternoon all..

Build 2 is going remarkably fast, the cost was justified as a winter project to keep me amused until March... however it now looks like I won't be able to avoid finishing it by mid next week at the very very latest

A question arises however in what does the team think about the hub.

The rim with a rear Q100 has been built by BMS and is centred onto the hub rather than the axle, so choices are to either dish the rim or offset the hub between the dropouts.

Of course at this moment I'm preferring the simple offset option which will result in a very close but not perfect to the mm centre, but will bow to expert opinion if there are reasons why the longer option of dishing is preferable.

Pros and cons ?

I didn't know BMS offered that level of flexibility on wheel builds...I asked them to build me a 349mm 16" rim and they said "only sizes on site" or some such reply ;-)

My project is going to take quite a bit longer than yours, but I also have a Q100 motor sitting on my desk right here..I've got to power it up to test it and will try out the throttle and cruise feature, but that's as close as I'll get until my freewheel arrives... fingers crossed for before Christmas/snow and ice!

 

[Old_Dave]

I didn't know BMS offered that level of flexibility on wheel builds...I asked them to build me a 349mm 16" rim and they said "only sizes on site" or some such reply ;-)

Just as well I wanted and got a 20" then ... lol

 

[Jeremy]

My experience has been that it was pretty easy to dish the Q100 to get the rim centred in the dropouts, even with a 20" wheel. I found it much harder to get enough dish with the larger diameter BPM motor in a 20" rim though, so ended up with it very slightly offset from centre.

What I found with the very short spokes on the BPM wheel build was that the drive side spoke tension was as high as I could safely go, yet I couldn't pull the rim over any further without losing too much tension on the non-drive side.

 

[flecc]

There's no problem with using a shim either, as long as the wheel are going in the same direction they don't need to be in line. One commercial and successful cargo bike has an over 2" offset of the rear wheel to the right and that's not detectable in riding it.

 

[Deleted member 4366]

Afternoon all..

Build 2 is going remarkably fast, the cost was justified as a winter project to keep me amused until March... however it now looks like I won't be able to avoid finishing it by mid next week at the very very latest

A question arises however in what does the team think about the hub.

The rim with a rear Q100 has been built by BMS and is centred onto the hub rather than the axle, so choices are to either dish the rim or offset the hub between the dropouts.

Of course at this moment I'm preferring the simple offset option which will result in a very close but not perfect to the mm centre, but will bow to expert opinion if there are reasons why the longer option of dishing is preferable.

Pros and cons ?

You can't shim if you want a disk brake, Otherwise it makes no difference which method you use.

 

[Old_Dave]

Thanks guys

Don't ever intend to add a rear disc so shimming it is... turning down the axle spacer from the gear side of the hub and adding to the 'disc' side now

 

[Deleted member 4366]

Thanks guys

Don't ever intend to add a rear disc so shimming it is... turning down the axle spacer from the gear side of the hub and adding to the 'disc' side now

Don't forget that if you do that you won't be able to have many gears.

 

[Old_Dave]

Don't forget that if you do that you won't be able to have many gears.

Errrrr... can't see there being an issue, (he said, never having changed the offset before) but will set up and adjust the derailer bracket if necessary and will report if its all gone wong

 

[Jeremy]

Errrrr... can't see there being an issue, (he said, never having changed the offset before) but will set up and adjust the derailer bracket if necessary and will report if its all gone wong

Best check that the free wheel still clears the inner face of the drop out after shortening that side. I think that may be the main issue, rather than the dérailleur bracket, but I may be wrong.

 

[Old_Dave]

Best check that the free wheel still clears the inner face of the drop out

Thats the measurement I was working to, lol

Wheel back in and bolted up, clearance from freewheel to drop out = 5.92mm

V brakes and derailer re adjusted following me setting them up with the wheel out of centre.

Pleased to report that all is well and the wheel is indeed in the middle for diddle

 

[Deleted member 4366]

You have to measure the gap you have for the free-wheel. From memory, the stack height of a 7 speed is about 40mm, but you have to allow for a slight gap each end. Compare that with the distance from the side of the motor to the drop-out, which is also about 40mm without shortening. If you shorten one of those bushes, a 7 speed won't fit. The more you shorten it, the more gears you lose.

 

[Old_Dave]

Luckily I only wanted to use the 6 speed freewheel I already had.

But point taken for the next one, lol


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[Old_Dave]

First quick blast..

I fully intended to use 36v on the first test but CBA so stuck in the 12cell lipo, nothing went up in smoke so I suppose all is well.. lol

Controller is stock, will adjust current and LVC this week some time (by my calculations replacing the relevant resistor with 16k should do it, may even fit a 10k in series with a 10k lin pot and tweek it exactly if I CBA)

Not quite the same acceleration as the GNG mid drive but that's not any surprise at the moment, maybe the extra current will help.

Top speed (down the little test hill) measured with GPS and that is about the same as the mid drive.

Cadenance is 'just' acceptable with 52 / 14 unlike the GNG small chain wheel which isn't

Hub is quieter than the mid drive.

Pedal assist ... works, but I don't like it, I much prefer being in charge of the throttle (maybe I'll get used to it or disconnect it)

The 6km button ... now that was 'great fun' when using the extra volts from the lipos

Whilst moding the controller I'll do as pointed out earlier and swap the brake input to high and then connect the in line sensors (wont use diodes to isolate the control wires as I think it will be ok just connected together, down side is that both little leds may light at the same time.. and may hinder any future fault finding)

Will try and remember to go out again and measure amps before moding the controller

Edit : Done, 15.63A peak on about 46v (only using 5800ma pack for this test, will add the other 5800ma for test 2)

Bottom line is that I like this Q100 hub very much and its a lot stealthier as well, may not be quite as nice at 36v though, but I'm very unlikely to find that out)

 

[Deleted member 4366]

Photos please!

 

[Old_Dave]

Will do ... As soon as its light


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[Old_Dave]

Pictures as requested

Chain line in 6th, rubber cover removed from axle to show that there is a bit more thread on the right than usual.. but the tyre is centre.




Sensor fitted this side as there wasn't enough gap behind the chain wheel, sure I could of taken time and trouble to make space but it didn't seem worth the bother.




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[Old_Dave]

The front..

Added drop of clear silicon to top of brake sensor to prevent water ingress and a little drip loop.




Handle bars, right hand throttle converted to left hand (reverse magnets and modify the spring)



Still a few bits to do to the controller and battery isolator, found a couple of diodes that were left over from a previous project so will fit them to isolate the brake sensors.


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[Deleted member 4366]

This setup looks like a really good solution for a light folding bike. Cheap too.

Where did you get the 5v for the brake switches, and have you connected both signals to the high voltage brake connection (SH), and does it switch off when the signal is high or low?

 

[Old_Dave]

5v stolen (shared.. lol) from the throttle connector, and both signals will go via diodes to SH... I expect that it will work on signal high only but I'll see if there is any quiescent current from the sensor to use for the best of both worlds 'signal missing'.

Whilst your here, lol

Thanks again for that lipo suggestion,


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