How2 design ergo handle and stress on the arm/elbow

General
1

Present wrist and arm problems have caused me to think about designing an ergo handle for MUni/ trials.

Pardon the following long-winded presentation, I did the best I could to make my point clear. I am looking for riders to answer with either technical expertise, and/or knowledge of how the muscles of the forearm and hand work in concert.

I did a search on handles and found only the stuff on Coker stuff, which doesn’t help me here.

Has anyone tried to build a handle that feels more relaxed to the hand? I ride most of the time left hand linked to the handle, but at times, I do use my right hand, but it isn’t my strong side.

If I sit on my MUni and relax my left arm and let it meet the handle (Miyata style), my left wrist is rotated slightly to the left. If I was holding a metal post in my hand, I guess, that it would be pointing to 2:00 o’clock and slightly upward. Grabbing the Miyata handle, forces the wrist to rotate to the right and then you have to move the top of the nuckles almost level(parallel) with the top of the seat handle. This seems like an unnatural position for the wrist and hand. Why not design a handle that matches the more natural wrist/hand position – that which I refer to as the two o’clock position.?

I think the Reeder handle sort of does, this, but from looking at the images on unicycle.com, it doesn’t point upward, but more or less horizontal.

Then there is the GB4 handle for Cokering or 29ing. But from looking at the pictures at unicycle.com, this handle points away from the rider. I was looking more for something that might be sort of a Reeder handle style, but pointed more upward to a more natural position.

So, has anyone built a handle as I have mentioned - that ‘s assuming you can visualize the configuration from my description?

Now, for the next part, I wonder what stresses would be placed on the elbow and shoulder when doing MUni or trials compared with using existing (Miyata style)handle designs. IMHO, while the current Miyata style handle design places my hand/wrist in an unnatural position, it does seem to however, create a solid muscle platform from which to direct the movement of the uni when hopping or gapping. But it does IMHO present problems for the muscles on the top of the fore arm and hand.

1 )If a newer more ergo design was used, would the muscle platform be the same, stronger or weaker and would more stress be placed on the elbow and maybe even the shoulder with the newer ergo design?

In summary, I am looking for answers to the above question #1 and number 2 (below).

  1. Does anyone have a handle like this, knows anyone who can make it, and can share any experience with it?

I won’t even consider mounting a brake handle on this new style of ergo handle at this point. Let’s keep that out of the discussion for now.

Thanks,

2

Have you seen the handle made by Scot Wallis:
http://www.wallisdesign.com/HANDLEpics.html

It has a nice comfortable shape and a different angle than other handles. It seems to position the hand in a natural and comfortable position.

3

Rod,

I’ve had a few good rides on the GB4 handle, one or two brief rides on a Reeder, and thousands of kms on a std KH handle. Quite a few kms on the miyata too (but forget the Miyata- it’s almost the worst handle I’ve ridden)

My thoughts:
-The KH handle is a solid platform but not a large one to rest your hands on. I don’t think it places your hand in an unnatural position, but it does hurt after yanking on the handle for a while (but so will anything). It has a lot of pulling power though.
-The Reeder handle allows your palms to close over the bar (a palmar grip) and is angled to give a lot of pulling power. I think it is more comfy than the KH for distances but I don’t think it has any more pulling power than the KH. The Reeder handle actually sits quite high (ie points upwards) when mounted to a KH seatbase, because of the curve of the base). I don’t think you’d want it pointing much further up or it will have no power at all when pulling on it- your elbow would be at too flexed an angle.

-The GB4 handle is a great setup for distances, and lets you cruise at high speed for long periods because of the position your hands rest in (kind of like a time trial bar on a bike). You can also put both hands on the handle, and that takes a bit of pressure off your saddle area. However, because of the way it is angled (11 and 1 o’clock positions), it has very little power/leverage. It freaks me out everytime I descend a steep hill- I ended up on my bottom for the first time ever today when the unicycle went out from under me. That would not have happened with a KH handle. The GB4 also has less leverage for off-the saddle power climbs, but is great for just cruising up a hill. I have modified it slightly by putting a cut down bar-end on one of the prongs of my GB4 handle- that’s helped a bit, giving more hand positions for high leverage situations.

I don’t quite understand the first part of your question- but as far as I can make out- in terms of hand stresses, the KH/Miyata style handles uses a hook grip (kind of like holding a suitcase), whereas the GB4 and Reeder handles utilise a palmar grip (holding a bar). Both of them utilise the same powerful extrinsic muscles of the forearm. I don’t think the stresses on your hand are any different.

In terms of your forearms, the GB4 handle sit your forearms in a relatively neutral position, whereas the Reeder/KH/Miyata in a slightly supinated position (turned anticlockwise- radius and ulnar). I think for long periods the neutral position is going to be more comfortable, since you’re not using muscles to actively hold the forearm supinated.

The stresses on the shoulder and elbow would depend on how flexed they are, which is dependent on how low/high the handle is mounted. I don’t think there’s too much you can alter with these particular handles because they attach to the seat (although you can adjust seat angles and also where you drill the holes in your seatbase for the handles). The GB4 handle seems to sit quite high though.

Anyway, I’d get the Reeder handle if you want to do MUni; or the GB4 if you want comfort for long distances, and not too fussed about leverage.

Hope that’s useful,

Ken

4

It’s a long time since I worked as a sports trainer, so I’ll leave that all alone, but as a sculptor, I will share my thoughts from a technical angle.

One way to make a grip that will perfectly fit your hand would be to use a synthetic polymer*over a ‘keyed’ metal armature (skeleton).

For example, make an armature in steel/aluminium which projects forward from the front handle bracket bolts, or the seat post (like a brake lever). Have grooves/ lumps (like on rebar) for the gloop to bond/key to.

With gloves on, mix up a batch of muck and form a ball in the palm of your hand. Squeeze it over the armature and keep still until it sets up enough for you to let go.

Generally the longer something takes to dry, the stronger it will be.

When it’s dry file off the sharp bits and sand it all smoooth.

  • Gloop ideas:

    auto-body-filler
fibre reinforced epoxy
PC-7
JB Weld
expanding polyurethane foaming resin

-Polyester resin might be a bit brittle

If you wanted to, you could do the maquette in wax/plaster/plasticine etc and cast multiples for others to use, in gloop as above.

I’m imagining that such an item might have lots of little overhangs etc which would preclude a rigid mold - you might think about a product from Corning called “Silastic 3487” for a flexible mold making material. It’s not cheap, but if you were planning on making lots, it would be economical.

If you’re interested, i could sketch out a rough plan for you, and attach it as an image file.

David

5

Thanks for the mention, JC.

Rod,

When I started designing my handles, it was because I felt I would be able to lift the muni more forcefully with less hand and arm pain if I had a handle that actually fit my hand and had a way to wrap my thumb around it. Also I wanted a handle that did not flex so that if I needed a quick small lift to clear an obstacle I would not have to compensate for loss of response from the handle flex. After a year of testing my molded handles I can say that I can pull much harder on climbs and hops, and I do not have any problems with hand pain. I do get muscle soreness in my forearm when I do a lot of hard climbing, but it is because I am able to pull harder without finger pain stopping me, so that’s a good thing.

My “DeathGrip” handles that I will be releasing soon were designed by going through the hand positioning exercise you describe. First, I designed and CNC machined a mounting base for the handle, then attached and shaped modeling clay to make a rough shape while sitting/standing in the riding position on the unicycle. I then made a rubber mold from that shape, cast some urethane resin copies, and modified those by filling and grinding them until I had a shape I liked. I then used that as a pattern for a more refined mold to make prototypes for testing. I am on the 3rd revision now and the shape seems to suit almost everyone who has tried it. Any shape is a compromise because of the wide range of hand sizes and shapes, and people’s individual biomechanics.

My DG handles slope down to the thumb side, not up as you describe. The angle you describe does not seem natural or comfortable for me or other people I have used for input, but that doesn’t mean it wouldn’t be good for you. You could easily cut and re-weld a Reeder handle to do that. You might try mounting a stock Reeder with washers under it to test the angle before actually modifying it.

If you want to sculpt your own shape, the method Tall_Dave outlined will work. Finding a material that can take being slammed on the rocks repeatedly is the challenge.

Scott

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6

I am familiar with the Wallis DEATH GRIP handle. I saw it at CMW 2004. I did place my hand on the handle, but for a short time, and forgot to really try it out on the trail while it was mounted on Scott’s MUni. I do remember it being VERY comfortable. Unfortunately, as I was considering this thread, I couldn’t remember how it was angled, so I figured that someone would clarify this. Fortunately Scott did this in addition to a concise background of the development of the hand position.

I wanted to see if there was anything that someone else had made. You never know what you will find popping up in a thread. The muscle information was very important to me.

To more clarify the hand position I was referring to, I was looking for a position that would be created if one formed a fist and then put a slight bend at the elbow, with knuckles parallel to the body.

I currently run a Bridgeman handle on my MUni that I really have enjoyed. It is mounted to a CF Miyata base, but it still puts my hand at an odd angle. Since no one has, at least in the last few years had problems with tendonitis in the arms, probably tells me that current handles on the market work well for nearly everyone and that my issues may be centered on poor technique.

Ken’s muscle info is extremely useful. Scott’s idea about placing washers under a reader handle may work as an inexpensive and simple alternative to finding what I think would work for me. For Tall – Dave, I wasn’t planning on making a run of these. If it came to some sort of design, it would be a one-off.

Anyone reading this really should grab (no pun intended) one of Scott’s DEATH GRIP handles when they become available. It’s light and strong and doesn’t flex.

7

totaly! when i offered mine up for sale a couple weeks ago i couldnt belive it sat there for three days before anyone bought it whats up with that?

its was even # 007, lucky obie.

8

Hey Scott, i sent you a PM.

-Tom