handcycle owner riding off-road

one-off handcycle offroad sports cycleTHE SUITABILITY OF HANDCYCLE MODELS

There are a few other brands of handcycles that claim to be suitable for off-road riding. We often get asked about these. The following are One-Off's biased opinions. This is in no way an objective evaluation.

Before talking about any of the other brands specifically, there are a few things to discuss first.

HIGH SPEED STABILITY
We take high speed stability very seriously. It makes sense. If you sell a vehicle with our traction, super low gearing and the resulting ability to climb big hills, then you are responsible for the ride back down the mountain as well. Where is the fun in climbing a huge mountain if you have to creep back down riding the brakes the whole way? In mountain biking, we grind up hill, sometimes at a slow walking pace, but we get the reward of flying back down at speed. Our favorite test track is a a bit of barely used mountain dirt road. It starts out straight, steep and bumpy, then turns left, right, and left, without getting any less steep or bumpy. The rider gets bounced about. You need to shift your weight from side to side if you want to carry the most speed through the turns. Coming up on the first turn, there is some serious braking required.

RIDING POSITION
There is a long history of leg powered vehicles that allow us to compare the recumbent and the prone riding position. Two of the "ten reasons" on our web site are about this. The short version is that if you want to use your arms to absorb bumps in the road, you need to lean forward onto them. All things being equal, with human powered vehicles, arm or leg powered, the prone riding position beats the recumbent riding position over rough terrain at high speed.

HANDLEBARS
First, does the bike have handlebars? Most handcycles don't.
Where does the rider hang on, to steer and control the vehicle on high speed downhills. Without handlebars, the bike is controlled from the crank handles. These are mounted on bearings. They swivel, which does not help the steering precision. Add in bumps, and the rider bouncing up and down over rough terrain, and the swivel gets worse. If the vehicle doesn't have handlebars, it can't be very good at high speed descending in off-road conditions.

Those that do have handlebars, generally fall into two categories. One type has bicycle handlebars and a bicycle stem. The downhillers do it this way, as does the Explorer. This looks good. It seems cool to have mountain bike bars and stem, but we disagree with the function at high speed.

disabled athelete on off road bikeThe other kind of handlebars are a separate left and right side, mounted more or less directly onto the respective kingpins. This is the way One-Off does it. We got the idea from lots of high speed testing and from John Castellano and his Cobra. The Explorer II also uses this style, and many leg powered trikes, but not, by our reckoning, correctly.

We have done extensive testing on adjustable prototypes in an attempt to learn about high speed stability. We have compared many different combinations of caster angle, axle offset, and handlebar configuration at speed over rough dirt. After years of testing, it turns out, the answer is all about handgrip location. Place the handgrips on the kingpin center line but just ahead of it. The handgrips on the Cobra are the length of a suspension stem ahead of the kingpin center, ours are about 1 1/2 inch ahead. Further ahead, tends towards more stability. Our choice, (always a compromise) has less offset, to keep the handlebars from being too far away.

ride one handed
sport hand cycle
The difference in performance between the bicycle style handlebars and the separate right and left hand style can be described in a few ways. Imagine riding the vehicle 25 mph downhill with one hand. So you are leaning forward but only one hand is there to hold you up. It is pretty easy to imagine the sudden turn that would result from doing that with the types that use bicycle handlebars. Similarly, imagine riding the separate right and left side types with one hand, if the grip is anywhere other than on the king pin center line, or ahead of it. With the One-Off, even a rider with a very high level of disability can take one hand off the bars and the vehicle will tend to go straight.

bumps
Another problem with the bicycle style handlebars shows up when the terrain gets bumpy. The rider is only "connected" to the bike in a few places. The seat, the knees and lower legs, and the handlebars are the only points of contact. If you are bouncing around because of the rough terrain then all of these points of contact become critical. Any vehicle will be subject to unwanted steering over rough terrain due to the rider hanging onto the handlebars while being tossed around. Bumps throwing the rider side to side and up and down, will inevitably get to the handlebars, which may move, like it or not. Remember, at 25 mph, even the slightest movement of the bars will cause sudden steering. The actual amount of bar movement at this speed is measured in millimeters. This has to be felt to be fully appreciated. The bicycle handlebars are about 20 inches wide. This gives way too much leverage. This is fine at 2 mph, but at 25, over bumps it is terrifying and dangerous.

"rider trail"
The other important thing to picture is what John Castellano calls "rider trail". Everyone knows that the steering geometry of a properly designed vehicle has some "trail". Car designers talk about it differently from the motorcycle people, who use different words than the bicycle builders, but the idea is the same. The proper combination of steering pivot angle and axle offset provides straight line stability. Your vehicle should go straight by itself. When you let go of the steering wheel/handlebars, you go straight. The new thing here is that we are now talking about human powered vehicles. These weigh less than the rider. The rider's weight is now a factor. In a car, the weight of the driver means practically nothing. But with human powered vehicles, the weight of the rider becomes a very important ingredient.

Imagine a sheet of plywood covered with grip tape. Put the vehicle with rider onto the plywood. Stand to the side and tip the plywood up as if you were going to dump the bike and rider off onto their side. This duplicates the forces experienced riding on a side hill and/or high speed cornering. Any properly designed vehicle will automatically turn downhill using the plywood test. There are some that don't. The "lean steer" Freedom Ryder and the Lightning handcycles are suicide on wheels and proof of the validity of this test.

But, the more important test, that applies to us human powered types, is, instead of pushing to the side on the vehicle, push on the rider's shoulder. The cornering/side hill forces are then going through the rider's body to the seat, leg supports, and handlebars. During this test, the bicycle handlebars style will turn up hill. In spite of the properly done steering geometry, the rider weighs so much more than the bike that the 150lbs of rider overpowers the centering effects of the caster angle. The rider is hanging on to the handlebars and resisting being thrown to the outside of the turn. With our style of handlebars the "push on the shoulder test" causes the bike to turn downhill. This is "rider trail".

• grip travel and radius

As a kid, I can remember a neighbor of mine who had a bicycle with a steering wheel. Instead of handlebars, it had an actual steering wheel from a car. But that is the only exception to what is normally quite standardized. Two wheeled vehicles have handlebars, cars have a round steering wheel. There is no controversy, no debate. Handcycles are in a different category. They are human powered (ie. lightweight), more than two wheels (ie. don't lean into the turns). Those of us who work on "human powered vehicles with more than two wheels"(hpvmttw?) talk about handlebars all the time. There is no consensus, lots of debate, and an astonishing variety of types.

Two wheeled vehicles are inherently stable at high speed. Even a cheap bicycle will "ghost ride" until it slows down and falls over. Given our current level of understanding of steering geometry, two wheeled vehicles are just plain safe. Cars are also safe at high speed. Take your hands off the steering wheel and it will go straight. Cars also have the added advantage of having effectively two systems of steering. One, at high speed is the tiny motions used to keep the car in lane at 65 mph. Look at your hands the next time on the highway. Even a lane change at 65 requires just an inch or so of motion at the hands. The second "system" in car steering is the three or more rotations of the wheel used when parking. High speed: tiny motions keep you in your lane. Low speed: Many rotations. Human powered vehicles with more than two wheels have a much harder time. A steering wheel with three turns lock to lock would work, but no one wants that. To get them to turn easily from lock to lock while stopped, and be stable at 30mph is almost impossible.

To compare some of the many kinds, let's look at the rider's hands on the hand grips and plot out the actual path that they take when swinging the handlebars from full left to full right. Imagine a dot of light on the back of each glove. Turn the shop lights out, grip the handlebars and quickly swing the bars back and forth to see the path traced by the light. Since handlebars always move about a pivot point, we will be seeing a left and a right arc. These arcs will be in different locations relative to the rider. They will be of different lengths and of different radii. We can see the lock to lock grip travel distance.

Greenspeed: bars about 18 inches wide, pivot in center of bars, grips at either side of rider's hips. grip travel about 8 in. radius 9 in.

Wind Cheetah: bars are on a "joy stick" mounted on a universal joint. about 6 inches wide. operate with a twisting motion. grip travel 3 in. radius 3 in.

Four cross: bicycle bars on a bicycle stem, pivot at steerer on stem. grip travel and radius similar to greenspeed with a stem added.

Cat trike: separate left and right style. stems extend straight back, motion side to side near rider's hips. grip travel 6 in. radius 6in.

One-Off: separate left and right style. stems extend straight forward. motion is mostly a twist of the wrist. grip travel1.5 in. radius 1.5in.

Bill Darby: separate left and right style. pivots down low, bars extend straight up. forward and back motion. long travel and radius

Maybe it is misleading to lump leg powered and arm-powered vehicles together but I just want to show the amazing range of ideas out there.

Another thing to factor in, is the amount of force required at the grips. I've read recumbent trike reviews that talk about how the steering was "light" or "quite responsive". But with a hpvmttv, at 30 mph, "light" is the last thing you want. At 2 mph, "light" is fine. If you are maneuvering around in a parking lot, no high speed stability is required. This is a trade-off or a compromise. Wide bars traveling through a long arc gives more leverage whether you want it or not. The One-Off is hard to turn while stopped. We have very limited leverage at the handgrips. We have the best stability of all the styles, at high speed. We have a natural centering motion to the grips. Relax and you go straight. It takes effort to move away from straight ahead.

FINALLY, THE OTHER BRANDS

I don't pretend to know about every brand in the world, just most of them. We are talking about off-road capability. I like to design to a "contest" of some sort. For example, the off-road handcycle race course in Crested Butte CO. I'm not saying that some of these vehicles aren't great, some of them are. But since this is my web site, I get to pick the "contest".

We can eliminate any that don't have a good method of self propulsion: can't climb any better than an everyday chair.

downhiller handcycle -- Downhillers

sport wheelchair isn't an off-road cycle -- What Most Other All Terrain Wheelchairs Look Like

We can eliminate any that are front wheel drive. No grip on the climbs; don't even think about braking hard while cornering.

off road handcycle -- Lasher

upright off road handcycle -- Varna

We can eliminate any that have a recumbent riding position even if they are rear wheel drive. no good on the high speed downhills. neither of these have handlebars. The Hase beats us on sheer climbing traction. It is up to them to design their own race course where they win. Until then we have Crested Butte CO. That course is hard, but even in the rain, we can grip on the climbs.

recumbant bike for off-road riding -- Greenspeed Recumbant Bikes

high speed hand cycle for paraplegics -- Hase Bike Handbikes

knobby tread tires for rough terrain -- Reactive Adaptations - They are licensed by us. We have some differences but it is basically a copy. They place the rider higher in the air. This is a trade-off between ground clearance and trying for the lowest center of gravity. They seem to be willing to put up with some steering cable slack at extreme steering angles, we have no steering cable slack. They use 1 1/8 headsets. Given that even the one inch headsets that we use are completely overkill, we have no explanation for using the heavier, larger size.

That leaves Jaroslaw Rola from Poland. This is also a direct copy of the One-Off, that's good, but what silly design errors!
Look closely at their videos and photos to confirm the following:

Kingpin inclination.
No kingpin inclination (See video explanation below - Greenspeed calls it center point steering) Your riding mower has this, as do antique farm carriages, and your car. They are right.

Chest steering direction.
Unbelievably, and I'm not making this up, they have it backwards. Lean your chest to the right, turn left!

Gearing.
Without any Schlumpf Mountain Drives, it is nearly impossible to match our low gears. We have two Schlumpfs. They are very expensive. We don't regret one cent of the cost.

Handlebars.
See the above description of bicycle vs. separate right and left bars.

Suspension.
Double A arms cause front track length to vary which makes the rider "tyred". Suspension is a wonderful thing but you have to be careful if you also want to go uphill. There are lots of leg powered trikes with various kinds of suspension. This is great fun, but problems with scrub and pedal induced actuation are still unresolved.

Wheel size.
The first 100 or so One-Offs had three 20 inch wheels. We have gone to a 24 in the back because we like the way it rolls over bumps, but this is not without plenty of compromises. The frame now has to be longer which means it is heavier and slightly more flexy. The wheel itself is also heavier, and not as strong nor as stiff. 24 inch wheels on the front would offer some advantages at high speed and rolling over bumps but look at the trade-offs. To match the turning radius of the 20 inch wheels is very hard. The back of the front tire intrudes on the rotation of the cranks ie. the back of the rider's hand gets close to touching a front the tire on full lock turns. This makes the frame wider which means heavier, less stiff, and less able to fit between trees. Do you squeeze between trees where you ride?
Smaller wheels are lighterstrongerstiffereasiertoaccelerate.

And a leg powered one
In 1996 we bought a leg powered recumbent trike. We wanted to be able to use it to get a feel for many different design elements before building our first serious prototype. We could now ride a trike to feel the frame stiffness as determined by the main tubing diameters, lengths and wall thicknesses. We could feel the steering geometry and the handlebars. Gearing, braking, bump absorption and many other things made it quite a good investment to ride this for a few months. We live in Western Massachusetts in the Berkshires. It is not very high elevation but the roads are as steep as anywhere. It seems that one of the main things we learned from owning this trike is that it's builders seem to live where it is flat. Everyone was happy with it down in Northampton, where it is flat. Out here, in the "hilltowns" it was a complete flop. As slow as a recumbent on the uphills and terrifying on the downhills. The handlebars are about 20 inches wide and move through about 8 inches of travel from lock to lock. This is great at 5 mph in a flat parking lot, but here in front of our house on a 9 % grade, going 25 mph, it is scary. We learned to try to relax on the handlebars. It was much better if you could relax into the seat so that you could almost let go of the handgrips. We even got pretty good at this, but it was a strong lesson. The steering geometry can be right, but "rider trail" is more important.


 

 

 
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