Rotational weight and traction- Mtbr.com

# Thread: Rotational weight and traction

1. ## Rotational weight and traction

This is just a random though that popped into my head:

Say you're pinning it, off the brakes and railing a corner, would your tire's knobs dig into the ground better due to the added rotational momentum of a heavier wheel vs a lighter one?

I realize that even if a heavier tire had this advantage, the advantage of lighter one would still out weigh it. Not trying to prove that a heavier wheel is better. Just throwing a random thought out there

2. heavier tire, heavier wheel, heavier bike, all have the same effect of increasing traction.

3. Doesnt the direction change while turning mean that with bigger mass you have to fight a bigger force and therefore actualy have less traction as the force in the direction you were previously going would be higher?

4. Believe it or not weight doesn't play as big of a roll in traction as you would think. The extra weight pushing the knobs DOWN is also push the rest of the bike STRAIGHT instead of turning. Its hard to explain when you cant draw a picture Basically your getting the down force but its outweighed by the side force.

5. Boy, this thread is not going to go to any good places

So here's my contribution: off the brakes, the tire is in static contact with the ground at any moment, so there is no force that is slowing or accelerating the wheel (except friction, I suppose) so wheel momentum is really unimportant in that case. Most of the forces will be caused by the far greater force of momentum of a 160 or so lb rider and their 30 lb bike. Wheel momentum is important when considering braking or acceleration.

6. The tire is a circle, any change in centripetal acceleration due to added weight (that out ward pushing force) is held in place by the structure of the tire, the rim and the tension in the spokes, since this force is evenly distributed (and evenly canceled) radially out from the axle nothing happens to increase traction.

If this wasn't the case and there was an in balance that would allow this kind of extra traction your wheel would be falling apart.

7. The benefits of heavy wheels/tires are...
• Durability
• The ability to run lower pressures without damage (which can definitely improve traction)
• Larger more aggressive tires (which can definitely improve traction depending on conditions)
• Lower likelihood of being deflected adversely by random objects you may hit

The negatives are...
• Takes more effort to accelerate or change direction quickly
• Lots more rolling resistance
• Not as fun to jump with unless you are going to land short or just want to fly straight

Flat tires and bent rims suck as you watch your friends ride off down the trail

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