September 2, 2014
FLO Cycling - Tire Pressure
We get a lot of questions about the optimal tire pressure to use with FLO wheels. There are a couple of common misconceptions with regards to tire pressure.
- 120psi is the optimal pressure.
- Higher tire pressures equate to lower rolling resistance and make you faster.
Let's talk briefly about those misconceptions.
I believe the 120psi misconception has trickled down over the years. I think it was a combination of narrower wheels, the pressure recommendation on the side of a tire, and word of mouth. Over the years the width of rims have changed and tires have changed as well.
Higher Pressures Make you Faster
Taken to extremes, this seems to make sense. If you ride down the road with a tire that has really low pressure, it's easy to see that this is much slower. Naturally, if low pressure is slow, then high pressure is fast, right? Actually, it is right, but only up to a certain point. If a tire has too much pressure, it actually, starts to bounce around on the small imperfections in the pavement. All of this bouncing wastes energy and makes you slower.
So what Should You Do?
There's a place somewhere in the middle where the correct amount of tire pressure limits the "slowness" created by too little pressure, and limits the bouncing you experience when you have too much pressure. Tom Anhalt, author of the blog Blather 'bout Bikes, has studied tire pressures and rolling resistance at length. When I have a question about rolling resistance and tire pressure he's my go-to guy. We've even shared wind tunnel data with Tom in the past to find the tire that has the optimal balance of rolling resistance and aerodynamics.
When I asked Tom about the optimal tire pressures for FLO wheels, he gave me the following dataset.
Note: Never exceed the maximum pressure recommended by your tire manufacturer AND never inflate to a pressure less than the minimum pressure recommended by your tire manufacturer. Riders over 180 lbs or 81kg are advised to inflate their tires to the maximum pressure recommended by their tire manufacturer without exceeding 150psi or 10bar. Riders less than 110 lbs or 50kg are advised to inflate their tires to the minimum pressure recommended by their tire manufacturer. The above data set is a modification of the data found here. The data was modified to adjust for the width of FLO rims.
So how do you use this table? Let give a couple of examples us the standard table.
Rider Weight: 150lbs
Tire Size: 700 x 23c
Knowing you have a 700 x 23c tire, you will start by using the green line. Now find your weight - 150 lbs - on the Y axis and then move over to the right until you hit the green line. Next, draw a line straight down to the X axis. The value on the X axis in this case is about 100 psi. This is your recommended tire pressure.
Rider Weight: 170lbs
Tire Size: 700 x 25c
Knowing you have a 700 x 25c tire, you will start by using the red line. Now find your weight - 170 lbs - on the Y axis and then move over to the right until you hit the red line. Next, draw a line straight down to the X axis. The value on the X axis in this case is about 95 psi. This is your recommended tire pressure.
I hope this article has been helpful. If you have any questions at all, please leave them in the comments section below.