Prosthetic and control mods for one handed riders

[trixter]

In response to people asking me to post this information in a thread that they can freely discuss ideas and other things I have done just that.

First I have one hand. What I did is for me and me alone. You are free to use, adapt or modify what I have done to fit your particular need, desire or other requirement however I am not saying that my way is best for anyone but me and me alone.

Since I am missing my right hand and would like to be able to use both a clutch and front brake I have looked into ways to move the brake to the left side. I had looked into auto clutches and did not like them, particularly the $650 cost (even though some places would give me a disabled rider discount of about 10% that still put the cost quite high). I do not really mind shifting either. I also looked at stuff like the Klever2[1], but $2k for the levers only with no master cylinder that seemed even worse price wise.

This got me to thinking a bit about the problem, in base terms. I need a left handed master cylinder, a shorty lever (for either the clutch or the brake based on what feels better) and enough room on the handlebars to mount both on the left side. I can mount them slightly offset from each other so they dont get in the way of each other.

For a left handed master cylinder I decided a hydraulic clutch would work well, and there are many such clutches in the same size as many brake master cylinders. This means that pressure and other features of the brake should work identically on a wide variety of bikes.

For the throttle the problem is a little more complex. I am missing my right hand, wrist and about 1/3 of my forearm. I could go with a premade prosthesis[2][3][4] but there is a cost factor associated with it, and the only one I would want would be the touch bionics one, which is several times the cost of a traditional prosthetic hand ($50k and up). I am also more adept at not using a prosthesis than using one, in short I cant type well with a prosthetic hand, I cant do many of the other tasks that I do daily with one or it will slow me down dramatically to have it. To that end the money justification for merely riding a bike seemed quite high. I decided to make my own.

Here are my blog entries of the process that I went through, including a few dead ends that I took along the way. For me with my arm I am able to almost do a pull up before the socket comes off, but it does come off eventually. This means that I can hold on and not be thrown back during acceleration. I can also relax my arm and it will slide off with almost no force. If I dump the bike I will separate no matter what, a very good thing as I do not want to be drug down the street by my bike if I fall. The only disadvantage currently is that it can get cold. I plan on fixing that with some "heating tape" which is similar to glove warmers. Basically it is used for keeping water pipes above freezing in cold weather, but its a flexible 'tape' that you wrap around whatever you want to keep warm and plug it in. When current is applied it will generate a small amount of heat. I will need to play with this so that it does not get so warm I end up with a burn or melt my jacket, this will be a voltage based control system which is not terribly difficult to construct.

I also made it with a quick disconnect, part of it will remain on the throttle and be similar to a palm rest. The remainder will come off and I can take that with me (which avoids having to deal with pigeons doing naughty things to it, or careless people doing stupid things and making it unusable for the ride home). This also prevents it from getting super hot just sitting in the sun while I am indoors or whatever, or freezing in the winter.

My blog urls in order are:
http://www.0xdecafbad.com/2010/10/ca...he-prosthesis/
http://www.0xdecafbad.com/2010/10/ma...om-a-negative/
http://www.0xdecafbad.com/2010/10/creating-the-socket/
http://www.0xdecafbad.com/2010/10/ca...-and-painting/
http://www.0xdecafbad.com/2010/11/fi...ew-of-project/


Footnotes:
[1]http://www.klever2.com/Gallery3.html
[2]http://www.oandp.com/products/trs/
[3]http://www.touchbionics.com
[4]http://www.prostheticarm.com/

[Weldangrind]

I'm a little unclear on how the device attaches to the throttle, but I'm sure it will make more sense when you apply it to a bike. Have you considered a spherical rod end instead of a turnbuckle? They're also available as a right angle stud and socket, with the original application being carb linkage in a car. Both options are very affordable, and they might provide more precision. Just my $0.02.

Going back to the auto clutch (which would still allow changing gears), perhaps a clutch assmebly from an eighties Honda ATC could be adapted. That would eliminate one lever entirely.

Consider a Chinese ATV rear brake lever assembly for an economical master cylinder solution. I bet that would work well for a left hand brake with a front wheel caliper. They often have controls on them that could be used for high / low beam, horn and signals. Mine does.

[trixter]

Originally Posted by Weldangrind

I'm a little unclear on how the device attaches to the throttle, but I'm sure it will make more sense when you apply it to a bike. Have you considered a spherical rod end instead of a turnbuckle? They're also available as a right angle stud and socket, with the original application being carb linkage in a car. Both options are very affordable, and they might provide more precision. Just my $0.02.

Do you mean a ball and socket joint? If so those are not suitable to my needs. In order to turn the throttle I cannot have the joint flex in an up/down motion. What I have done gives me rotation (pronation/supination) by allowing the turnbuckle bolt to screw in/out. It also gives me flexing left/right across a horizontal plane (ie thumb/pinky side if your palm is down). For rotating the throttle I rotate my arm at the shoulder which translates to a turning force on the throttle. Imagine having a wrist brace, like the ones commonly used for carpal tunnel syndrome. In order to turn the throttle you have to rotate at the shoulder (and your elbow will move along with your hand).


As for how it attaches, in the final pictures the other half of the CB mount is not present. Refer to the final blog url (images below) and look at the mount itself. The design is in two parts with 4 bolts that hold them together. The design is to allow for it mounting around a mirror post (or other tubular shaped item). Basically I loosen the bolts, then slide it on the throttle and tighten the bolts. Then when pressure is applied to what is now a palm rest the throttle will spin.

Here are some images showing the mount on a mirror for reference, just replace the tubular post to the mirror with a throttle.




A palm rest (aka throttle rocker)

Going back to the auto clutch (which would still allow changing gears), perhaps a clutch assmebly from an eighties Honda ATC could be adapted. That would eliminate one lever entirely.

Yes it would and for many that seems to be acceptable. For me I prefer to have a clutch.

Consider a Chinese ATV rear brake lever assembly for an economical master cylinder solution. I bet that would work well for a left hand brake with a front wheel caliper. They often have controls on them that could be used for high / low beam, horn and signals. Mine does.

The bikes that I have looked at have those controls on the left. The only control I have seen on the right (for the bikes I have looked at) is the starter. The control block will not be moved or altered for my needs.

The only disadvantage is that if the engine stalls I must stop to restart it. I *could* put it in neutral and reach over with my left hand to start while rolling but I would rather avoid doing that. Some may consider this an essential safety procedure since you may not always be able to coast to the edge of the road, however my options are adding a start button to the left side or reaching over and right now I have decided to push that decision off to a later date and just try not to stall out and if I do get off the road with whatever forward motion I have.

The only "trick" for using a clutch master cylinder, which was mentioned on my blog but not here, is to use a banjo bolt with a pressure sensor for the brake light. These are readily available from a variety of sources. The only drawback is that you have to actually apply the brakes to get the light to turn on. With many brake master cylinders you can lightly press the lever to get just the light and no braking force applied. This can be useful for warning people to back off, and that 'feature' will not be present on the modded bike.

[Weldangrind]

It's not a trick with the ATV version. Mine is also equipped with a simple momentary switch that operates the brake light. The application is a GY6 150cc quad that has no brake pedal.

I think I get the throttle control now. You're clamping onto the throttle; correct?

[trixter]

I should clarify that the red part in the final image on my blog would form the palm rest (with its other half wrapping around the throttle itself). In the above post that is the mount by itself (middle pic).

If this is still unclear lemme know and I will try to think of another way to explain how it mounts.

[trixter]

Originally Posted by Weldangrind

It's not a trick with the ATV version. Mine is also equipped with a simple momentary switch that operates the brake light. The application is a GY6 150cc quad that has no brake pedal.

I found some that are $26 delivered, however I cannot find specs on them. The bikes I was looking at (as in plural) were generally 16x18 or 16x19. Do you know what that one is?

For those that dont know master cylinders have a dictated bore size, using one that is different alters the lever travel as well as the braking force applied. While you can use a different bore size the lever may be super sensitive or it may require more travel to provide the same braking force.

Depending on application this may be the desired effect. If you go too far out of spec the slightest lever movement may cause the brakes to be fully applied not giving you a gradual application. In the other direction you can end up pressing it against the handlebars and it is still not fully applied.


[/quote]I think I get the throttle control now. You're clamping onto the throttle; correct?[/quote]

Yes, I am clamping the red part (CB mirror mount) around the throttle.

This also means that it is generic across multiple bikes. I can leave the CB mount on a couple different bikes and when I pick one to ride that day I just attach the clevis pin and off I go.

[Weldangrind]

I don't know the specs of the master, and I only presume that the front and rear calipers on Honda clones are the same; they look to be. Even though Honda clones tend to be on the lower end of the quality scale, parts are plentiful and often interchangeable with genuine Honda stuff, which broadens your search criteria. That said, you might be able to use a complete rear brake setup from an ATV and mount the caliper on the front wheel, thereby providing a matched system. You'd just need a shorter hose.

[FastDoc]

Trixter.

I am impressed by your ingenuity and enjoyed reading your blog(s). I'm glad you have found an ally here in the form of our Chief Engineer, Weldandgrind.

[midlifekrisiz]

a co-worker here has a young son that rides a 110 skidoo and he was born without fingers on his left hand.....the war amps made a special attachement for his skidoo that he slides his fingerless hand into and it alows him to ride....they also made him one that clamps onto his hockey stick so he can play.

[trixter]

Originally Posted by Weldangrind

I don't know the specs of the master, and I only presume that the front and rear calipers on Honda clones are the same; they look to be. Even though Honda clones tend to be on the lower end of the quality scale, parts are plentiful and often interchangeable with genuine Honda stuff, which broadens your search criteria. That said, you might be able to use a complete rear brake setup from an ATV and mount the caliper on the front wheel, thereby providing a matched system. You'd just need a shorter hose.

For the qlink I would not need a new hose because the stock one is plenty long enough and this would take a little slack up. For a ninja I would because its a couple inches too short, and in doing so I would upgrade to stainless steel hoses. I can order custom length hoses for cheap (well reviewed) and they will put whatever end connectors I need on, whether right angle, straight, etc.

I havent looked at any honda clones in large part because of the CARB extortion fee, which many clone makers wont pay. This results in most of the clone bikes not being legal in the state.

[Weldangrind]

Originally Posted by FastDoc

Trixter.

I am impressed by your ingenuity and enjoyed reading your blog(s). I'm glad you have found an ally here in the form of our Chief Engineer, Weldandgrind.

I'm not ready for a handle like that, Doc.

[FastDoc]

You could share the job with Wild Alaskan. Some say he once built a Cessna out of coathangers and toilet paper tubes. :P

[trixter]

I am going to be making a new socket (the part that goes on my arm, blue in the photos on my blog). To that end I decided to push the socket I had a bit. If you watched the youtube video you would have seen a static loading of 2 2 liter bottles (about 8 pounds). I did over 60 pounds with the fiberglass shell before I decided it was enough.

I also took a hammer to the old socket to see how much abuse it could really take. It held up quite well to the impacts, there were a few cracks but it did not fall apart. Granted the way I designed it is to come off if I fall, I may revisit that at some point in the future and see if the disconnect should be at the "wrist" instead so that this bit of armor goes with me. That will not happen in the one I am going to make in the next day or two.

Since that was my first socket of that design (2nd socket ever) I think it came out fairly well and is fairly rugged.

As for remaking the socket were there any photos that should have been taken but werent? Photos that would make something more clear on the construction. If I am going to remake it from scratch I thought I should at least ask if I should reshoot anything.

[trixter]

Originally Posted by FastDoc

You could share the job with Wild Alaskan. Some say he once built a Cessna out of coathangers and toilet paper tubes. :P

Depending on the cessena that might be impressive :P

/flew a 182 in CAP

[Weldangrind]

If you choose to make it out of carbon fiber, I'd be grateful for some photos of that process. I've certainly worked with fiberglass and MEKP, but I'm not sure if the processes are similar.

I'd also like some information about where you buy carbon fiber supplies. I might like to experiment with it.