Short throw thumb throttle?

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Buk___
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Short throw thumb throttle?

Post by Buk___ » Jan 02, 2018 6:30 am

I currently have one of these throttles:
new-thumb-level-throttle.jpg
new-thumb-level-throttle.jpg (21.97 KiB) Viewed 572 times
But I find it has a much longer throw than I would like.

Are there non-twist thumb throttles with a shorter throw? Say 30-40° rather than 80-90°.

Unfortunately, they don't list this detail in the sales blurbs.

Thanks.

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Re: Short throw thumb throttle?

Post by dogman dan » Jan 02, 2018 9:51 am

Cut an inch off the lever would shorten the throw.

Could add a push button to the bars, that gives you a 100% throttle when used, for that quick stab of full boogie when you need it. still have throttle for when you need less.

If the throw is simply uncomfortable, you need to change the position of brake levers, so you can adjust where the throttle sits on the bars.

Or just go to the type most end up liking best, half twist.

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Re: Short throw thumb throttle?

Post by skeetab5780 » Jan 02, 2018 10:04 am

This one is not as long of a throw, I own both and like both on different bikes
https://www.ebay.com/itm/E-bike-Scooter ... Swj85YLpRA
Last edited by skeetab5780 on Jan 02, 2018 11:06 am, edited 1 time in total.

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Re: Short throw thumb throttle?

Post by Buk___ » Jan 02, 2018 10:26 am

dogman dan wrote:
Jan 02, 2018 9:51 am
Cut an inch off the lever would shorten the throw.
Then I would not be able to reach it.

dogman dan wrote:
Jan 02, 2018 9:51 am
Or just go to the type most end up liking best, half twist.
AFAIK there aren't any (half-)twist throttles that are compatible with dual twist shifters.

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fechter
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Re: Short throw thumb throttle?

Post by fechter » Jan 02, 2018 3:38 pm

The standard Bafang thumb throttle has about 45 degree movement.

search "Bafang Thumb Throttle" and you will find lots of places that carry them.
Bafang thumb throttle.jpg
Bafang thumb throttle.jpg (14.48 KiB) Viewed 534 times
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Re: Short throw thumb throttle?

Post by skeetab5780 » Jan 02, 2018 4:07 pm

Ya that is a vertical thumb throttle though, completely different animal IMO

You can get the Wuxing one that is vertical also if that style tickles your fancy

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ferret
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Re: Short throw thumb throttle?

Post by ferret » Jan 02, 2018 4:32 pm

Maybe combine a short "vertical" travel throttle with this product (or DIY somthing similar):

Image

http://www.wolftoothcomponents.com/products/remount

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Re: Short throw thumb throttle?

Post by Buk___ » Jan 02, 2018 6:18 pm

ferret wrote:
Jan 02, 2018 4:32 pm
Maybe combine a short "vertical" travel throttle with this product (or DIY somthing similar):

Image

http://www.wolftoothcomponents.com/products/remount

Avner.
You had me going there for a moment or two :)

Problem: It drops 'it' down; it doesn't move it closer. Then I noticed this (quote)
We do not recommend the ReMount for multi-chainring drivetrains (it sits where your front shifter does)
Uh-uuurgh.

However, it did stimulate some lateral thinking.

The problem with the radial (around-the-bar) models -- as opposed to the lateral (under-or-over-and-parallel-to-the-bars) models -- is that they are too far away from the normal hand position if you have half-twist shifters and two-finger brake levers.

If I buy a befang/Wuxing radial throttle and attach (epoxy) an horizontal (parallel to the bars) extension to the lever, I should (may) end up with something that matches my requirements.

Thanks to you, fetcher & skeetab5780 for the possibility of a solution to my conundrum.

I'll come back with pictures if it works...

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Re: Short throw thumb throttle?

Post by teklektik » Jan 02, 2018 6:29 pm

Or get a CA3 and set the 0-100% throttle output to be any fraction of the throttle throw that you want...
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Re: Short throw thumb throttle?

Post by Buk___ » Jan 02, 2018 6:39 pm

teklektik wrote:
Jan 02, 2018 6:29 pm
Or get a CA3 and set the 0-100% throttle output to be any fraction of the throttle throw that you want...
Besides that the CA3 is far from economical -- especially as it duplicates much of the function of the S-LCD3 LCD Meter I already have -- AFAIK, it would also require me to purchase a compatible controller.

I'm also unconvinced -- based on what I read, rather than actual experience -- that I would be able to match half the 0.8V - 4.2V output from my existing unit to a range that would make for a comfortable physical throttle.

I'm Aware that is based upon nothing more than hearsay and conjecture.

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Re: Short throw thumb throttle?

Post by MrDude_1 » Jan 02, 2018 10:35 pm

these type of throttles use gears to turn the pot inside.
you could always measure and buy or print gears for a different throw... then just add a throttle stop since it would reach its max limit sooner.
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Re: Short throw thumb throttle?

Post by fechter » Jan 03, 2018 9:07 am

Depending on how your existing throttle is built, it may be possible to modify it for a shorter travel, either electronically or mechanically.
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Re: Short throw thumb throttle?

Post by dogman dan » Jan 03, 2018 10:31 am

Lose the twist shifter on the right hand side is my advice now. Get a trigger, or even old school friction shifter. Then your existing throttle might work a ton better.

Lots of ways to go about it, including losing the left side shifter, then run the right side twist upside down on the left. That works amazingly well btw. Friction shifter for the front rings can then still be on the left, or mount it on the right, but out of your way. you hardly use that one anyway.

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Re: Short throw thumb throttle?

Post by Buk___ » Jan 03, 2018 10:32 am

fechter wrote:
Jan 03, 2018 9:07 am
Depending on how your existing throttle is built, it may be possible to modify it for a shorter travel, either electronically or mechanically.
I took a look inside:
ThrottleInternalsCropped.jpg
(213.17 KiB) Not downloaded yet
Where I've added a purple arc to the pic, there is a piece of metal -- presumably a magnet -- that get rotated past what I assume is a linear hall sensor, (but I cannot make out the markings to confirm) that I've lifted out of its seat for the pic and outlined in red.

I can't see any way of making the adjustment mechanically short of finding a suitably polarised and curved magnet half the length of the original.

Electronically, I'm guessing it should be a relatively simple circuit to map 0.8V through (say) 2.5V to 0.8V-4.2V using an opamp and a pot (or two) to adjust the gain and limits; but I'm not competent to design such a circuit.

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Re: Short throw thumb throttle?

Post by fechter » Jan 03, 2018 2:14 pm

Good picture of the throttle.

Finding an arc shaped magnet is usually pretty challenging, but it may work to simply cut (break) the magnet in half to get half the throw. You would also need to add a stop at the right spot. This may be as simple as drilling a hole and installing a screw.

Another possible option would be to feed the throttle with a higher voltage. Typical throttles run 5v or slightly less. If you fed it 10v instead of 5v, you could get full throttle in half the distance. The controller will have a 12v supply inside that drives the FET gates, and this usually feeds the 5v regulator. It wouldn't be too hard to locate the throttle power wire inside and re attach it to a 12v source. Typical hall sensors are good for 24v or so. I can't quite make out the number on the hall sensor, but we should be able to look it up. You would still need to add a new mechanical stop to limit the travel.
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Re: Short throw thumb throttle?

Post by MrDude_1 » Jan 03, 2018 2:42 pm

ahh a hall throttle. not a pot based one.

all you need to do is cut the magnet with a dremel and a cutoff wheel. that makes the electrical throw shorter. Then just add a screw in to stop it from going too far. The reason you use a screw instead of a hard stop is so you can adjust it with a multimeter.
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Re: Short throw thumb throttle?

Post by Buk___ » Jan 03, 2018 3:18 pm

fechter wrote:
Jan 03, 2018 2:14 pm
but it may work to simply cut (break) the magnet in half to get half the throw.
MrDude_1 wrote:
Jan 03, 2018 2:42 pm
all you need to do is cut the magnet with a dremel and a cutoff wheel. that makes the electrical throw shorter.
Hm. I'll have to admit to not understanding how that would work?

As the full length of the magnet moves passed the sensor, it varies its output from 0.8V to 4.2V proportionally to some property of the magnet moving passed. Whether that is the strength of the field or its polarity I'm unsure.

But if I cut the magnet in half, then it would (wouldn't it?) mean that the output from the hall sensor would be limited to either 0.8V-2.5V or 2.5V-4.2V depending which half of the magnet I used?

Put another way, as the half magnet moves passed the hall sensor, it cannot know how much more magnet is coming, so it cannot scale the output to the length of the magnet.

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Re: Short throw thumb throttle?

Post by fechter » Jan 03, 2018 3:25 pm

It's a little complicated to explain and not all throttles do it the same way.
hall_effect_sensor_electric_scooter_cart_bicycle_how_it_works.png
hall_effect_sensor_electric_scooter_cart_bicycle_how_it_works.png (15.12 KiB) Viewed 414 times
Basically, one end of the magnet is south and the other end is north. Right in the middle, the flux will be zero to the hall sensor.
If you cut the magnet in half, it will still be south on one end and north on the other end and zero in the middle, just over a shorter distance.
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Re: Short throw thumb throttle?

Post by MrDude_1 » Jan 03, 2018 3:31 pm

When you cut a magnet shorter, one end is still south, one end is still north, and the middle is still the middle.
right now the magnet starts with one pole over the sensor, and as it moves closer to the other pole it raises the signal voltage until it is right over the end and it is sending full throttle.

if you cut the magnet shorter, it will move across from one pole to the other over a shorter throw... make sense now?

fechter has a good image on his post about it.
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Re: Short throw thumb throttle?

Post by Buk___ » Jan 03, 2018 3:33 pm

fechter wrote:
Jan 03, 2018 3:25 pm
It's a little complicated to explain and not all throttles do it the same way.

hall_effect_sensor_electric_scooter_cart_bicycle_how_it_works.png

Basically, one end of the magnet is south and the other end is north. Right in the middle, the flux will be zero to the hall sensor.
If you cut the magnet in half, it will still be south on one end and north on the other end and zero in the middle, just over a shorter distance.
Interesting. It shouldn't be too hard to test that.

And if it doesn't work out well, putting the two halves of the magnet back end to end would be back to status quo. (I think?)

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Re: Short throw thumb throttle?

Post by MrDude_1 » Jan 03, 2018 3:35 pm

Buk___ wrote:
Jan 03, 2018 3:33 pm
fechter wrote:
Jan 03, 2018 3:25 pm
It's a little complicated to explain and not all throttles do it the same way.

hall_effect_sensor_electric_scooter_cart_bicycle_how_it_works.png

Basically, one end of the magnet is south and the other end is north. Right in the middle, the flux will be zero to the hall sensor.
If you cut the magnet in half, it will still be south on one end and north on the other end and zero in the middle, just over a shorter distance.
Interesting. It shouldn't be too hard to test that.

And if it doesn't work out well, putting the two halves of the magnet back end to end would be back to status quo. (I think?)
I would either have a second throttle ready (they're usually pretty cheap) or go into this as a one way thing. I wouldnt count on being able to put it back to the original throw. the magnet is very brittle and hard to re-connect once broken.
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Re: Short throw thumb throttle?

Post by Buk___ » Jan 03, 2018 3:40 pm

MrDude_1 wrote:
Jan 03, 2018 3:35 pm
the magnet is very brittle and hard to re-connect once broken.
Wouldn't the two half just stick together? North pole to south.

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Re: Short throw thumb throttle?

Post by MrDude_1 » Jan 03, 2018 3:55 pm

Buk___ wrote:
Jan 03, 2018 3:40 pm
MrDude_1 wrote:
Jan 03, 2018 3:35 pm
the magnet is very brittle and hard to re-connect once broken.
Wouldn't the two half just stick together? North pole to south.
its not strong enough to stay together that way inside your throttle. this isnt a very strong magnet.
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Re: Short throw thumb throttle?

Post by Buk___ » Jan 03, 2018 4:16 pm

MrDude_1 wrote:
Jan 03, 2018 3:55 pm
Buk___ wrote:
Jan 03, 2018 3:40 pm
MrDude_1 wrote:
Jan 03, 2018 3:35 pm
the magnet is very brittle and hard to re-connect once broken.
Wouldn't the two half just stick together? North pole to south.
its not strong enough to stay together that way inside your throttle. this isnt a very strong magnet.
Understood, but it is supported on 3 sides by the plastic housing; and I could add some superglue.

But your point about having another throttle to hand is well taken. I've ordered a 130X.

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Re: Short throw thumb throttle?

Post by fechter » Jan 03, 2018 8:23 pm

If the magnet is magnetized like my diagram, then yes, the magnet pieces would tend to stick to each other if you put them back together. Some kind of glue is good. There are other ways the magnet could be magnetized which would make cutting it in half not work, but you should still be able to restore it to normal by putting the piece back. On yours, I think it will work.

Before you start cutting up the magnet, it might be a good idea to map the output voltage to see the stock output range. Then, after making a change, do the same measurement to see where the maximum happens, then make a stop so it doesn't go past there.

You can somehow disable the motor (brake switch, motor wires, etc.) and power up the throttle to measure the voltages.
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