Camber: Uphill or downhill pull?

Riding Advice
1

I find that my wheel is pulled to the uphill side as I cross a slope or deal with road camber.
So I push/pull the tire/handlebars to the downhill to counteract this force and give me a neutral feeling ride.

My thoughts are that if I’m crossing a slope, the uphill side of the tire has more surface contact than the right therefore causing more drag which pulls the left side of the tire back causing a left turn. (anybody get the canoe comparison?)

Because most people subconsciously counteract this force by turning downhill and now gravity is assisting the turn which amplifies and overcorrects it. That makes it feel like the wheel is being pulled downhill and that’s why most riders feel like the wheel is being pulled downhill when they ride on a slope.

Maybe…?

2

Yes, I have definitely noticed that a unicycle wants to pull in the uphill direction on a cambered road. I don’t have any canoe experience to refer to, but I think of it as being like tilting a wheel to the side on a level surface. For us the wheel is upright and the road is tilted, but the wheel tries to roll along a curve just the same. (See camber thrust for why this happens. Or roll a coin on its edge on a table. The more it leans over, the smaller the circle it rolls in)

I’ve found that banked turns are especially awkward on a unicycle because it wants to turn the wrong way, to go up the banking. My way of handling it is to cock the frame over as much as I can so that it’s more nearly square to the road surface while shifting my upper body the other way. It’s never really fun.

3

The way I envision it is by thinking of the tire surface as part of a giant cone - the center of the tire has a larger diameter than a than the outer edge. Now imagine rolling a cone along a flat surface - it doesn’t go straight, it rolls in an arc towards where the tip of the cone is/should

When we ride on a cambered surface the part of the tire contacting the road becomes conical too - the inside of the tire patch is smaller than the outside. The only way to offset this on a unicycle is to either attempt to ride with the tire perpendicular to the road surface or make tiny corrections using body inertia. Over time, we learn to do this automatically as we pedal.

Sam

4

Yes, totally agree. I didn’t want to go there. You put it into words a lot better than I would have. :smiley:

5

I always get pulled downhill, to the side of the road. Apparently that’s not a universal experience?

6

I was thinking hard about it, but then I stumbled across an eddyline and UPD’d …

7

I’ve learned to qualify my posts here with disclaimers like “in my experience” and “it seems to me.” If someone says you should learn on a 20" unicycle, the next reply might say that a 36" is the way to go. If I recommend raising the saddle or lowering tire pressure, another poster will swear that a higher saddle or lower tire pressure is where it’s at. :slight_smile:

I was thinking about riding a road unicycle on cambered pavement, where the reaction force from tire tread is most important. Riding muni on dirt on a sidehill, I can see it going the other way with gravity mattering more.

Have you had an experience where a banked corner worked in your favor, MrImpossible? I can’t recall ever feeling that. Maybe I don’t go fast enough.

8

MrImpossible, Can you say what kind of tire you have?

It has been reported many times on this forum that the type of tire has a large impact on how it responds to camber and how it makes smaller turns. The more square a tire profile is the more camber effects it where it tends to turn up hill on the camber. Also the more square the tire, the smoother it will turn small circles just by leaning into the turn. The more round the tire profile is the less effect camber will have and smaller turns will require air swimming jerky movements.

I suppose that the surface being ridden on makes a big impact also. The camber thrust effect requires smooth hard surfaces with good friction. When riding on soft loose lower friction surfaces this tire effect disappears.

Here are two extremes of tire profile.

Round Profile of Coker Non-Skid:

800×640 103 KB

A moire square profiled Nimbus Nightrider Tire:

748×589 47.2 KB

Jim

9

The camber thrust explanation makes good sense to me. However I don’t believe the rolling coil analogy is the same effect. I think the rolling coin effect is purely a gyroscopic effect. In unicycling, especially with larger wheels and faster speeds, both the camber thrust tire effect and gyroscopic effect will have an impact how it handles.

Jim

10

I just took a couple of wheels out for a quick test ride on my street to make sure I wasn’t misremembering-

  • 24" wheel with a 2.35" Schwalbe Crazy Bob tire - basically smooth with a grid of small grooves, round profile, higher pressure - headed downhill to the curb.

  • 26" wheel with a 2.8" WTB Ranger tire - small knobs, lots of empty space, lower pressure, not so round - headed downhill with a vengeance. This is probably the worst tire I’ve ever ridden as far as camber goes.

Offroad I don’t notice nearly so much, it’s just one more technical issue among many. But I still head downhill.

11

As Eddie would say, it’s different to all of us, but in my case, it’s the same: the camber drags me to the downside. Laws of gravity is what is at work, or so I think (thought?).

I read the tip on twisting the bars and thought “got to try that”, but by the time I got on the uni several hours later, I had forgotten which way I should twist. So I tried both ways, and the one that worked for me was the one that made my shoulders/torso face the upper side of the camber. And I remember thinking “this makes sense, it counteracts the gravity that wants to pull me to the downside”.

When I got back home from my ride, all excited by this new discovery, I read this thread again and thought “oh no, I did it all wrong, what happened!!!”. Thank you MrImpossible for your input!
The twist-the-handlebar is still the best tip I’ve read in a while, but it’s a starting point, not a one-fits-all solution. All tires and all riders react differently to camber (I guess part is the apprehension of what is going to happen, I find myself tensing up when I get to a seriously angled camber). Which is probably an explanation to why there’s not a definite solution to the camber problem - this thread is not the first on the subject, and not the last for sure.

12

I think both kinds of “pull” are real. Canoehead (the OP) describes riding across a slope and being steered up. It’s a steeper, shorter-term situation than riding along the edge of a road. I go up a steep little side slope on our weekly Road rides, and I have to remember to lean into it the right way, to come out on the narrow, downhill sidewalk that follows.

If you actually try to ride a straight line along a slope, like one of those ramp-like curbs, you will definitely have to work to keep the uni mid-slope. How hard you have to work is probably affected by your tire’s profile, as well as how much it’s inflated.

On the road (or bike path; any good bike path is sloped to one side or the other, for drainage), it’s usually a pretty low angle, but you can feel the effect. For me it wants to push me downhill and I have to work to keep a straight line.

In Ride The Lobster (a big unicycle stage race in 2008) I was most comfortable, and able to ride fastest, right on the centerline. Race officials didn’t like that. But mostly we were in the middle of nowhere, with very light traffic, and I wore a mirror. Don’t tell anyone.

On America’s Most Beautiful Bike Ride, a big recreational ride around Lake Tahoe, we ride on mostly 2-lane roads, much of which has pretty pronounced camber. That wore me out on my first time; I remember having to push harder with my right leg to keep angling the wheel back up the hill. I asked more experienced riders, like Nathan and Beau Hoover, and they basically said you get used to it after a while. Apparently a much longer while than the 72 miles around the lake!

Turning your handlebars, which really is meant to go along with turning your seat and handlebars, is intended to help you sit at a slight angle, and make it easier to do that slightly uneven pedaling to “balance you” against the camber. I’ve done that once or twice on long Road rides, and I felt that it worked for me. Originally I figured out that method for getting around 200 meter athletics tracks when we did indoor unicycle racing. Those ovals are almost all turn, and it’s hard to maintain the tighter turn at high speed. turning the seat made it a little easier.

In the end, I think a lot of it is also about how the rider approaches the idea of doing the ride. I watch Ed Pratt in his YouTube videos of riding all over the world, and see that whatever the road puts in front of him, he’s going to deal with. He might have to go a little slower, but he’s going to get there no matter what.

13

I paid close attention to my ride today and found that I could put slight twist on the bars on a lightly cambered trail and dial it up and twist harder to match steeper sections as I rode through them.

Like a gigantic anti-camber dial.

It’s also not a twisting of the shoulders for me.
Just a slight touch on the handlebars.

6" of new snow for today’s ride.
It was like I had dropped down one skill level and one year of conditioning.
Very humbling.

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