Let's Talk Tires!

What are the benefits of narrower tires. I want to increase my speed.

 

I don't know much about tires, but wouldn't the "fastest" tire depend on the type of race and conditions. I would think that in something like rain or a course with lots of tight corners (eg. crit) you would go for a bit more grip in order to go through corners faster; thus having to use less energy to get back up to speed. maybe someone could chime in on this as well.

 

Basically, there are two elements to the rolling resistance of a wheel on pavement. One is friction, which is directly proportional to the downward pressure of the tire at the contact patch multiplied by the area of the contact patch. Actually, it's a bit more complicated because pressure is higher at the center of the patch than at the edges, but the point is clear. The more force on the patch and area of the patch, the more resistance. So given that rider and bike weight are constant, you can reduce the contact patch by using a narrower tire and increasing air pressure, which increases pressure over the pavement, or you can reduce pressure over the pavement by increasing the contact patch (using a wider tire) and reducing air pressure.

The other element is deflection by the texture of the road surface. At high pressure deflection pushes against the forward momentum of the wheel. At lower pressure deflection is absorbed and the tire rolls more easily over surface imperfections.

So what does this mean?. First, the tire should be selected based on the rider's weight and the road surface. Heavier riders on rough roads roll better on fatter tires. Second, regardless of surface or rider's weight, a tire with a supple casing should roll faster. Since the tube is part of the package, using tubeless tires or using thin, supple latex tubes helps. Third, the relation between pressure and surface area favors surface area. In general, using a slightly fatter tire to reduce pressure more than compensates for the increase in the area of the contact patch.

There are no specific universal answers. In general, though, supple tires with smooth treads made from fast compounds, probably sized wider than you think you'd need, will probably help you go faster.

 

Define "narrow". Narrow tires have marginally lower aero drag than wider tires. At a given pressure narrow tires have higher rolling resistance than wider tires, assuming all the tires in question have the same construction (i.e. are the same model). Obviously wider tires at the same pressure offer a more comfortable ride. Tires with more puncture protection tend to have higher rolling resistance. Tires with a higher thread count tend to have lower rolling resistance. Race tires tend to have lower rolling resistance as a result of their generally thinner tread (thinner tread leads to lower rolling resistance), their lower level of puncture resistance, and their generally higher thread count. Race tires tend have shorter lives--sometimes by a huge amount--than training tires. Rolling resistance example: a 165lb rider on tires with a rolling resistance of 0.0035, riding at 25mph has to expend 2.93 watts to overcome rolling resistance. If he double his speed, the watts required doubles. If the rider loses 10lbs, i.e. he loses 6.1% of his weight, the watt's required to overcome rolling resistance goes down 6.1%. If he gets a tire whose rolling resistance is 80% of the original, the watts required will be only 80% of that required for the original tire. Pick a tire that best fits your requirements, but understand that will necessarily involve compromises.

 

FWIW. Without seeing how your bike is set up, I think the average rider can improve their speed by simpy lowering their handlebars (if the rider's flexibility allows it, that is) ... ALSO, regardless of the handlebar's relative height to the top of the saddle, riding with your hands in the Drops more-often-than-not will be beneficial to increasing your speed BECAUSE there is probably more wind resistance created by YOUR riding position than by the width of your front tire ...

Also, with consideration to wind resistance, don't wear baggy clothing.

 

Thanks for all the replies. This helped a lot.

 

Keep in mind a wider tire has a lower rate of deformation (tire changing shape, primarily at the road surface, that 3-5 inch patch section) , which results in 1. less likelyhood of getting pinch-flats, 2. corners better as it retains more contact patch on the ground, 3. tend to be more comfortable.

I'm a big proponent (I'm 180 lbs) of using a road 23c tire for the front , and a 25c for the rear (in general, the majority of the time, for training/touring, etc). If your lighter (say under 150 lbs), possibly you can use a 20c front. Watch out, those 18-20c tires tend to be for Jr. / lady riders (up to 145 lbs). Higher thread count (tpi) is nice, but tends to cost more $$ incrementally. I strive to at least get a 60 tpi tire, as I've found that is the minimum tpi that is accpetable, and drastically reduces your chances of getting a puncture from a torn, etc. Possibly running a Kevlar strip in the rear tire can be a good move, but when taking corners it can give the rider a funny feeling on the rear end(no pun intened), and can possibly come into contact with the tube/pinch it.

I was a Wheelman 12 years ago (riding), but in many ways will always be a Wheelman (technically speaking).

 

@Adam-from-SLO

Good information. I am a big guy 5'11" 205 pounds so I will stick with a wider tire.

 

@ Ryan,

Yes, I would do a 23c or 25c up front , and on the rear do a 25c or 28c (check your frame to see if a 28c is too wide/or not, you don't want to necessarily be rubbing chain/seat stays with tires!!).

Thats the problem, many people are "too" concerned with weight, that they will put on too small of a tire diameter, and often times more so then not pinch-flat, etc. They are like major tube consumers, and the last time I checked tubes are 100% rubber = natural resource. Bite the bullet, put one size bigger of a tire on there = saves tubes, saves $$ and TIME changing out tubes/patching tubes in the long run. Sure, your wheel weight goes up 1-2 oz. but big deal. Also, try and stay away from "light" tubes, as they tend to have a thiner skin of rubber = not nearly as durable.

Also, watch out for how manufactures sell/ advertise their product. For example, Vittoria "Zaffrino" tires = $12-15, come in a standard "Zaffrino" tire that only has 24 tpi. A "Pro Zaffrino" = $20ish has 60 or 66 tpi. About 40 tpi difference.... = BIG Difference !