xroadcharlie

We had a bunch of new MUP's installed in my neighborhood. There fresh asphalt smooth as glass. Many of the roads I ride on are asphalt too and in very good shape, Just not new. I was surprised how much difference it makes in rolling resistance with my cheap 26 x 1.9" (48mm) city tires on my comfort bike. I can shift up 1 cog (about 10%) and maintain the same cadence with about the same effort.

I wonder if a good quality 700 x 32mm tire on a road bike would show the same results on these two surfaces. Maybe with cheap wide tires there is simply more room for improvement.

PeteHski

I think you will see much the same difference. Our local roads are of mixed quality and going from say rough chip seal to smooth tarmac makes a big difference to the speed.

tempocyclist

Huge differences in RR between surfaces.

The country roads around here are "dead" feeling and very rough, like coarse sandpaper or worse. If I head to a big city and hit smooth new roads, I'm instantly 2-3 km/hr or more faster for the same effort.

zandoval 

Ridding the line can get ya some speed too...

vegfemnat

International Roughness Index is the standard that is most commonly used worldwide formeasuring pavement roughness. Pavement roughness has a direct correlation with not only comfort and speed but also fuel efficiency of vehicles.

Roughness profiler instruments are very pricey.But nowadays our smartphones have sensors that can relatively accurately measure pavement roughnes.

You can find such an app on Android or IOS store. I personally use Roadbounce which uses the International Roughness Index standard. Just mount your smartphone vertically on the dashboard of your car or a phone holder on your bike and create roughness profile maps of your city roads. Then share them withfellow cyclists.

Your will get color coded roughness patches on the map and also a measure of the surface roughness value on specific routes. Share with fellow cyclists or publish an objective data driven ranking of the best routes to cycle on in your city or country.

A ranking system may also incorporate other data driven properties pf routes such as volume of traffic and so on. Data that is easily collectible and relatively objective and statistic.

I have created such a ranking system for my city in India. It was a fun exercise.

GhostRider62

When one of my training routes have new albeit not the greatest pavement laid down, I measured Crr of 0.0042. Now five winters of salt later, it is visibly very rough and I measured approx. 0.006 (maybe a touch higher). This is enough to take me from 15 mph down to 14 mph or about one tooth on the rear. I had the pleasure of riding on brand new and perfectly level pavement about a week ago. I did about 10 miles on it. It was also very warm day (low air density) but it all made me feel 18 year old again, 22 mph was effortless.

vegfemnat

How do you measure the rolling resistance coefficient?

indyfabz

Yeah, and I hate it. There is a route I do a couple of times/year for long weekend tours. There are a couple of multi-mile stretches where the pavement becomes rougher. Even though it’s not particularly rough, I can still notice the difference in required effort.

The route for the 2002 Cycle Oregon had a lot of chip seal. The tiny vibrations caused lots of butt irritation after a couple of days. Chamois cream became like crack. People were desperate for it after the mechanical support ran out of stuff to sell. During one evening meeting it was announced that a new, small supply had come in. After the meeting people hustled over to the sales table to snatch it up.

staehpj1

Running a little lower pressure can help on the rougher chip seal surface.

t2p

agree ... wider tires with reduced pressure appear to be a good combo for the rough surfaces

Peruano

If you've never ridden on marble floors you have missed a treat. I can't tell you what large government building I used to have access to real early in the morning. Polished stone is noticeably faster and more comfortable than almost any other surface (I'm ignoring ice). Come to think about it, we all notice how riding on the white line is easier than the adjacent paved surface.

RChung

There are several ways, but a relatively easy way is with an accurate speed sensor and power meter. Coefficient of rolling resistance scales exactly like slope, so Crr = .001 has as much effect on work or power as riding up a 0.1% slope. I've done a small amount of comparisons between IRI and Crr in the sense of "this roughness costs about as much energy as going up a hill that is X% steeper." With a speed sensor and power meter, you can also estimate the losses to riding on loose surfaces, like sand or gravel, and how losses vary with tire characteristics like width or inflation.

GamblerGORD53

Cement is fastest. I notice instantly after going on a sidewalk.

pdlamb

First, I have to agree about new pavement. Although it's usually only a quarter to a half a mile, I've started to shift my commute route to the newest pavement streets on a parallel grid just for the pleasant (and fast!) ride. Country rides, not so much, because there's not so much of a grid out in the county, so traffic and scenery are higher priority.

Second, sidewalk riding, really? Most of the sidewalks I could ride are old, cracked, and bumpy, as well as interrupted by driveways way too frequently. On weekends I'll ride a busy street instead of the parallel MUP that was apparently built by a tech high school class -- rough and bumpy expansion joints are worse than the old pavement on the road.

Third, IME there's a pretty narrow range of tire pressure on wider tires where the ride is smoother but the rolling resistance and speed are not significantly impacted. Also IME that pressure is higher than most people say it is for my roads and streets. I'm circling back to a default 32-35 tire width for most pavement as the best compromise between ride and speed. (Of course, lots of unpaved or really, really poorly paved roads benefit from wider tires.)

RChung

Most outdoor velodromes use concrete (though some use asphalt and others use a tropical hardwood--but that's not common). Most indoor velodromes use pine or spruce. The surfaces for indoor velodromes are generally faster than outdoor velodromes.

SkinGriz

Interesting. I used to zoom an RC Car up and down the hall of army barracks. It did seem faster than on the street out front.

SkinGriz

Not to mention how many sidewalks have a Magnolia/Jackoranda/Maple etc making the side walk resemble a MX track?

xroadcharlie

As a recreational cyclist changing tire pressure on my rides isn't practical with the different surface conditions I encounter, But perhaps for long rides on the same surface or touring it mighty be worth trying.

Even driving my GMG Terrain in northern Ontario on a rural road that was under construction I was shocked at how the car reacted when I hit some recent crushed stone that had been packed. Dam near lost control even at just 50 mph. The effects on a bicycle must be significant there too.

Around here, some of the sidewalks are in worse condition then the road, but when the street is too narrow, or too busy for both, I ride them anyway. But pedestrians always come first.

KerryIrons

What you are seeing is called suspension losses. Most people think of rolling resistance as a function of tire flex losses, but an equally important cause is the energy your body absorbs from road surface roughness transmitted from the tires through the frame. When you lower pressure, the tire becomes more compliant and so less roughness is transmitted. This is why the "fast feeling" of high pressures actually slows you down (Bicycle Quarterly has documented this extensively). The perfect tire would have zero flex losses (hysteresis) and be so compliant that no energy would be transmitted through the frame. With a highly compliant casing, wider tires with lower pressures can be just as fast as narrower tires with higher pressures.

jon c. 

I ride on generally pretty good roads. When they repaved the main road through town, it certainly felt a lot faster when the pavement was fresh. But after six months it didn't feel much different than the rest of the roads.

rsbob 

Using Varia radar on this areas rough and abused roads, often with chip-seal, I can pick where I want to ride to avoid the worst of the worst, traffic permitting. That is usually the center-most part of the lane where motorcycles often ride. There is a discernible difference in speed and comfort between running in the tire ruts and the center. Thanks Garmin.

GhostRider62

Google RChung method and do some reading. Too much to write and it has already been written