Tire Pressure 101


Tire Pressure 101

Posted by trish in Blog

You don’t have to be a seasoned roadie to appreciate how tire pressure can influence your bike’s performance. Because modern bicycle tires are pneumatic (filled with air), tire pressure plays a huge role in how your bike rides and handles. Properly inflated tires not only give you lightweight suspension; but they also let your bike roll quickly, ride smoothly and fend off flats.

So what’s the proper tire pressure for your road bike? Unfortunately, there is no single or simple answer because there are so many variables. Rider weight, riding style, road surface, type of tires, and even the weather can all effect ride quality. The best way to find your proper tire pressure is a little trial and error!

Ready? Great. Let’s Go!

First, let’s start by looking at your tire’s pressure range on the manufacturer’s label, which you’ll find printed on the tire sidewall (it’s often on a small, colored label; but it might be molded into the casing, too, so look closely). The tire’s maximum pressure is NOT the tire’s recommended pressure. So unless you’re over 225 lbs., there’s really no reason to ever fill a tire to its max pressure. Oh, and never fill a tire higher than its recommended max pressure. That’s a big no-no!

A High Pressure Situation

Riding at too high a pressure may make your bike feel fast but may actually slow you down. Huh? Yes, it’s true. Roads in the real world aren’t basketball-court smooth. So if your tires are too hard, they have a tendency to vibrate, skip, and bounce over bumpy pavement, robbing energy and making for an uncomfortable ride. Ultimately, we want to use a tire’s inherent suspension to filter out road shock and vibration.

How Low Can You Go?

Okay, sounds like low pressure is better. No, not necessarily. If your tires are too soft, you increase rolling resistance (softer tires tend to deform more under rider weight and pedaling forces, producing a larger contact area against the pavement). Too-soft tires also greatly increase your chances of pinch flats.

 Say what? You read right. Pinch flats are most often caused when a tire that is under inflated hits road debris, a bump, or a pothole. Without enough air to fully support the tire, the impact can “pinch” or squeeze the inner tube all the way down against the metal rim of the wheel, and “pop,” you’ve got a flat. If it’s bad enough, you can also damage your wheel.

A Happy Medium

But properly inflated tires will roll over bumpy pavement smoother and faster and get you home without pinch flatting and jarring your bones along the way. Okay, so not too hard and not too soft. Let’s get more specific…

Conventional wisdom suggests that smaller road riders on standard 700×23 road tires who weigh120lbs and less should ride somewhere between 85-100psi; mid-weight riders who weigh between 120-170lbs should ride somewhere between 90-110psi; and larger riders who weigh more than 170lbs should ride between 105-130psi (unless the tire’s max psi is lower).

Of course, these ranges are only starting points. You should experiment within these ranges to get an idea for how your bike handles, reacts, and feels at different pressures. Honestly, it all comes down to personal preference! But don’t get too comfortable; here are some times you’ll want to make adjustments…

For Your Consideration

If you’re riding on wet roads, drop the pressure 5-10psi. If you’re riding on exceptionally smooth roads, maybe for a time trial, increase your preferred pressure 5-10psi. Additionally, you should run your front tire around 5psi less than your rear. Why? Because if your bike is fit properly, you’ll have more weight over your rear end than your front.

Pump and Circumstance

Now that you’ve figured out how much pressure you should be running in your tires, let’s turn to how often you should be pumping them up. You should get in the habit of pumping up your tires before every ride. While this might seem excessive, you’re less likely to pinch flat, which is certainly a good thing.

Remember, bike tires are not car tires. Those tiny air molecules will eventually migrate through the microscopic holes of the thin rubber inner tubes given enough time. As a guideline, a typical road bike tire can lose about half of its pressure within a week or so. So let’s say you don’t pump up for a whole week. You will be riding on half the pressure you normally ride and have clearly increased your chances of pinch flatting. Two weeks, even more so. And so on.

Bottom Line

Invest in a good pump with a clear pressure gauge, use it before every ride, and experiment with the amount of tire pressure you run until you find what pressure works best for you!

05 Mar 2014 No Comments

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