To be a flat tire or not to be a flat tire....

[SportySam]

So that is the question! I am not sure if I have a flat. The tires are holding air and are filled with air right before each ride, but as I am riding-I notice the tires are on the flatter side and when turning-it feels strange-like I caught an edge of the wheel and it sometimes feels like I am going to skid out....What is wrong with my bike and....how can I fix it?

[Tuckervill]

You're probably not putting enough air in them. You can't really go by the pinch test. If your pump has a gauge go by that. If not, use a tire a pressure gauge. If they are feeling squishy on corners they are just too low.

Even when I pump my road bike tires up to 100 psi (the max on these) they still flatten out a little when I get on (cuz i'm fat). I can't pinch them at all. But they don't feel squishy. That's the difference between yours and mine.

Karen

[OakLeaf]

Do you have a tire gauge? Have you had pinch flats when you've hit bumps?

What kind of tires do you have? What surfaces are you riding on, and how hard are you cornering? Knobby tires can feel very unsteady on pavement when you're turning with an extreme lean angle, so that you're beyond the tread on the sides of the tire.

Tires are part of the suspension system on any vehicle (the only suspension, on a road bike or hardtail, other than your own body), so they will compress somewhat under your weight. But they shouldn't seem flat. How does the tread wear look?

[SadieKate]

Even when I pump my road bike tires up to 100 psi (the max on these) they still flatten out a little when I get on (cuz i'm fat). I can't pinch them at all. But they don't feel squishy.

Noooooo . . . . that would be because you have them properly inflated to deflect and form to the road surface. Ever look at your car tires? If they don't squish a little, they're over-inflated. Too squishy and bike tires roll off the rim.

Why do people think that bike tires should be inflated to the consistency of concrete? If you do, go back to using iron and wood wheels.

[OakLeaf]

Why do people think that bike tires should be inflated to the consistency of concrete? If you do, go back to using iron and wood wheels.

Too much rotating weight from the iron, and I was getting splinters from the wood.


Srsly, tires are part of the suspension system, and once you remember to think of them that way, it all comes clear.

You want a stiff enough "spring" and enough "preload" that they don't bottom out (i.e. pinch flats or rim damage). You want enough damping that every little bump isn't soaking up your forward progress, but not so much that you're getting beaten to death, or that every little bump is launching you in the air. Just as you would dial down the compression damping on adjustable forks and shocks on very rough surfaces, you'd do the same to your tire pressure. Just as you'd use a stiffer spring and/or greater preload if you're carrying a lot of weight, a heavier rider will generally want higher pressure.

[SadieKate]

Yeah, getting them up to speed in a sprint sucks.

[Geonz]

The question is whether the tires change as you ride. If they're squishier at the end, there's a problem

If my tires are squishy at all to my fingers, they're too low (by the tire gauge and how hard I have to work). That's prob'ly my fingers, though... but I know lots of other people who do seem to want the biek wheel to feel like a car wheel and they should be stiffer than that.

[PscyclePath]

Why do people think that bike tires should be inflated to the consistency of concrete? If you do, go back to using iron and wood wheels.

Higher pressure tires = less rolling resistance = faster, easier to pedal.

But then again in mountain biking, less pressure lets the tires grip the ground surface better, and so you get more traction in the gnarly places. But there's a tradeoff... in this past weekend's Leadville 100 MTB rance, Lance Armstrong was running 26" tubeless tires at ~25 psi, but by the end of the race the back tire was pert near all the way flat. Same thing happened to last year's winner, Dave Wiens, with a similar setup in last year's race. There is such a thing as "too much squish."

Tom

[SadieKate]

Higher pressure tires = less rolling resistance = faster, easier to pedal.

Not necessarily a good thing. Too high and the tires bounce up and down and don't roll forward. They also grip the road surface less in corners. All tires can go faster when you're airborne. There is an optimum middle ground between "too much" and "too little."

And no one states tires should have no give at all.

http://mikesbikes.com/page.cfm?pageid=22&tipid=22

[SportySam]

You're probably not putting enough air in them. You can't really go by the pinch test. If your pump has a gauge go by that. If not, use a tire a pressure gauge. If they are feeling squishy on corners they are just too low.

Even when I pump my road bike tires up to 100 psi (the max on these) they still flatten out a little when I get on (cuz i'm fat). I can't pinch them at all. But they don't feel squishy. That's the difference between yours and mine.

Karen

I was wondering if I was too fat for my tires...hehe!

[SportySam]

I do have a pressure gauge. My Lbs told me to pump the tires up to 120.

But in relation to the other comments...what exactly in a pinch flat?

[smilingcat]

pinch flat aka snake bites.

this is when the pressure in the tire is low enough and your tire tries to go over a rock or hit a curb and the tire goes squish and flattens all the way so that the tire the innertube are pinched between the ground and the rim of your wheel. If there is enough pressure on the tire and the innertube where it flattened completely, the rim will literally cut two sometimes one small holes in the innertube and will cause a flat. The rim of your wheel act as a knife. Not a good thing.

It's also referred as a snake bite because it generally leaves two puncture holes next to each other like it was bitten by a poisonous snake.

If you are losing pressure while riding, then you have a slow leak. Get it fixed.

smilingcat

[OakLeaf]

If you inflate your tires to 120 and then ride for a while, what's the pressure at the end of the ride? I think it wouldn't be unusual for a high-pressure tire to lose 5# or even 10# over a 6-8 hour ride. I've never put a gauge on mine at the end of a ride, but they lose 20-25# from one day to the next.

If they're losing more than that, it's most likely a slow leak or possibly a bad valve, but it would be unusual to have the same thing happening with both tires at the same time.