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 Post subject: Dual throttles: Insane?
PostPosted: Mon May 27, 2013 14:12 pm 
Apprentice
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Joined: Wed Sep 30, 2009 18:07 pm
Posts: 24
Location: Birmingham, UK
For various reasons, the work on my bike has been painfully slow. I'll ride eventually. But for now I have a question about dual throttles.

Because both of my hands are variably bad, I want two throttles so that I have a choice. I have rheumatoid arthritis, so it's not just my hands that are problematic. I'm planning the following changes to the bike (BMW F650GS 2004):

automatic clutch (no clutch lever)
linked brakes: one control at right foot, one control at left hand in place of clutch lever
kliktronic shifter, buttons at left thumb.
heel-toe gear lever for when my left foot it up to the job

Also:
one twist throttle on right and one twist throttle on left.

My initial thought was that that was insane but then I worked through it and decided it should be ok as long as I don't choose to ride like an idiot.

I decided that the two throttles should be directly linked, with a pulley suspended across the cable somewhere down the bike. Pulling either throttle (or both) will lift the pulley, in turn pulling the carb cable. I considered other options where it was only possible to use one throttle at a time, essentially locking or disabling the opposite throttle. But then I asked myself this question: What if I need to accelerate out of trouble in a hurry and forget which throttle is live at that moment? Only dual live throttles get me out of that situation safely.

I'd like to ride safely and not get myself splatted. I would not abuse the dual throttle system; it is for my safety that I want the two riding options.

Do any of you have any experience with this sort of set up? Or suggestions that I may not have considered? I thought of a thumb throttle but my thumbs aren't up to that. I'm still pondering having the second throttle at the right foot, but it would need to work alongside the brake pedal.

Not everyone has thought my dual throttle idea was nuts, but enough of them to make me question my choice.

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BMW F650GS 2004.


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PostPosted: Mon May 27, 2013 16:57 pm 
Apprentice
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Joined: Wed Sep 30, 2009 18:07 pm
Posts: 24
Location: Birmingham, UK
Does anyone have any experience of having accelerator and front brake at the right foot? I can't quite see how that would be set up.

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PostPosted: Mon May 27, 2013 19:56 pm 
Hurricane

Joined: Sun Feb 20, 2005 17:29 pm
Posts: 293
Location: Pimperne, Blandford, Dorset.
In theory making a working throttle that operates off both left and right bars is possible.
I don't think it would be practical to have 2 throttle units with 2 sets of cables but you could make something on a revolving bar with a fitting for a standard cable (or cables on a two cable throttle).
I use 7/8ths alloy bar with a 1/2 inch hole to make custom bars and use 1/2inch stainless bar to make rods that run in the bar for gear changers on scooters.
The easiest way would be to make a straight bar set-up, but you may be able to use small universal joints to give you a set similar to pullback drag bars.
I use risers that have a 2 bolt fitting so they can be clamped to a yoke and don't need a normal set of handlebars I make 2 short bars like clip-on tubes and leave a gap in the middle.
Image
That's my vespa, you can see the left hand side is the gear change.


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PostPosted: Mon May 27, 2013 20:08 pm 
Hurricane

Joined: Sun Feb 20, 2005 17:29 pm
Posts: 293
Location: Pimperne, Blandford, Dorset.
The pulley that works my gear cables could be connected to to throttle cables, either one or push/pull cables.
Imagine the bars being set straight then the stainless rod running right through to a turning section on each end of the bars.
Or with 2 shorter stainless rods with a UJ in the centre allowing for a slight pullback for comfort for your wrists & hands.
My local Agricultural store sels different sized UJs so you should be able to find one small enough, then it's just a case of making it fit and work smoothly.
Personally I'd just get used to dead straight bars and have one less thing to engineer into making it work.


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PostPosted: Mon May 27, 2013 20:13 pm 
Hurricane

Joined: Sun Feb 20, 2005 17:29 pm
Posts: 293
Location: Pimperne, Blandford, Dorset.
For your application you'd only need a turning section the length of the grips each end of the bars with the centre sections that get clamped in the risers can be adjusted to what ever width you want the bars to be overall. I make my bars 26 to 28 inch wide for my own bikes but have made them upto to 36inches for a mate who is nearly 7 foot tall and almost as wide!


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PostPosted: Mon May 27, 2013 20:18 pm 
Hurricane

Joined: Sun Feb 20, 2005 17:29 pm
Posts: 293
Location: Pimperne, Blandford, Dorset.
Thumb throttles aren't bad, you soon build your thumb up and get used to them.
It depends on how strong the return springs on your carbs are, there are no springs in the thumb throttles I use.


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PostPosted: Thu May 30, 2013 13:25 pm 
Apprentice
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Joined: Wed Sep 30, 2009 18:07 pm
Posts: 24
Location: Birmingham, UK
That's a very different approach to what I had in mind! Interesting. And clever. Thank you. We do need to change the bars so I'll mention this as a possibility. Being such a different approach, it may just be easier for us to continue with the two throttle bodies. The second throttle does take up a little space on the bar, but the pulley connection I have in mind is simple.

Has anyone heard of throttle and front brake both at the right foot? I'd love ideas on how that might be set up.

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