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I have a dutch city bike (similar to the one shown below) with broad tires that I use for commuting short distances. When traveling on roads with a slight tilt (left to right, perpendicular to the road), I often find myself feeling unbalanced, as if tilt of the road is exerting a force on my tires, pushing me against the tilt.

What am I doing wrong? Can something be wrong with the bike/tires or is it just "me"?

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I am just a casual bike rider so I am not sure if this question is appropriate for this site. If not, my apologies. –  Mis Jun 10 at 20:20
    
I couldn't remember the technical word for it, but yes, left to right, not sloping upwards/downwards. –  Mis Jun 10 at 20:29
    
is your front wheel aligned properly with your handlebars? In other words, when you have your handlebars dead straight, is the bike actually moving straight forward? A small misalignment can make a difference. (Of course if it was this, you'd always veer in the same direction) –  PeteH Jun 10 at 20:32
    
Yes, I believe it is. –  Mis Jun 10 at 20:34
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camber or cant is the technical word for this - en.wikipedia.org/wiki/Cant_(road/rail) –  Tom77 Jun 10 at 20:36

3 Answers 3

If you feel no "tilt" on a flat road then there is probably nothing wrong. A bike's steering geometry is designed as a compromise, using terms such as "rake", "head angle", and "trail". A bike designed for agility will generally have a geometry that makes it turn downhill on a slope (if you let go of the handlebar), but a bike designed for stability (such as yours) will tend to turn uphill. This tendency is amplified by the wider, lower pressure tires.

I doubt that there is anything wrong with the bike, unless this effect is very pronounced.

If you find the effect unsettling you might be able to reduce it by increasing your front tire pressure 20-30%.

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Thanks, it is unsettling! I'll try increasing the front pressure and report back. –  Mis Jun 11 at 16:19

The tilt of the road is exerting a sideways force on your tyres: Camber thrust.

On a flat surface, this force is part of what makes a bike turn when you lean, but having the road tilted when the bike is upright will have the same effect (and so try to turn the bike). But on normal roads, it's a relatively small effect.

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This is not a full answer
It is too much for a comment
Please don't vote this down
But don't vote this up either

As for tire size that is not the problem.
My theory is you need to correct but I cannot demonstrate how much.
A larger tire is good as you will get the same amount of traction for less force.

Bike geometry is designed to hold a line on a flat cant.

If you hold a bike by the seat and balance it on flat ground the front wheel will be straight.
If you tilt the seat to one side or the other the front wheel will turn.
This is how you can ride with no hands.

So if you change the slope under the bike it is going to affect the natural line also.

I ran a test where I tilted board under the bike compared to tilting the bike on the board.
What I found was the wheel consistently pointed down hill - which made sense.

I think this needs a free state diagram that mechanical engineers do and I don't know how to do those.

Hopefully a frame designer will get on.

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