So I’m starting to get some hits on this blog now, about 10 a day which is a bit of a surprise. WordPress is pretty good in that you can see the search terms that people use to find the posts. The most frequent hits are for the Tubulars vs Clinchers post so I thought I’d go and have another look and this time dive into the world of clinchers.
So one of the most frequent questions posed on various forums and one I get asked (just this week) is ‘What is the best tyre?’ So a warning first, I’m an engineer by training so I love this kind of question and can wax lyrical about it. If you don’t like data then please skip to the conclusion. Although most of it is about clinchers much of the post can also be applied to tubular choice as well. I don’t have direct experience of tubular though so won’t be recomending any.
So before we get going then lets make something clear. There is no single best tyre! Any choice you make is a compromise and really it’s up to you to weigh up the factors and make a decision based on you’re own needs and the type of event that you are undertaking. That being said I’ve made my choice and I’ll discuss why later.
Lets start by having another look at what a clincher tyre is or if you have time have a quick read of my post on Tubulars vs Clinchers which explains most things.
Clincher Tyre (from Sheldon Brown):
Conventional tyres used on 99% of all bicycles are “clincher” type, also known as “wire-on.” They consist of an outer tyre (the “casing”) with a U-shaped cross-section, and a separate inner tube. The edges of the tyre hook over the edges of the rim, and air pressure holds everything in place. And here is a picture of a cross-section through a clincher.
You can see the yellow “bead” that hooks onto the rim. In this case this is a folding tyre and the bead is made from Kevlar.
Wrapped around that and forming the structure of the tyre is the casing. That’s the black fabric with pale edges in the U-Shape. Next you can see a strip of red material between the casing and the tread, that’s some puncture protection. On the top of that is the green and black tread. This is the bit of the tyre that actually contacts the ground.
A tyre design is a compromise between four main factors. Of course each one affects the others
1) Speed or rolling resistance
2) Puncture Protection
3) Length of service
Let’s spend some time going over each of these factors
Speed or Rolling Resistance
The speed of a tyre is governed mainly by three things. How supple the casing is, how thick the tread is and what it’s made from. A supple casing allows the tyre to easily deform to imperfections in the road surface. The thicker the tread is the more energy it absorbs as it rolls along. Some materials roll more easily than others.
Most tyres now have some form of additional puncture protection in the form of an armoured belt that wraps around the tyre. As you can imagine this isn’t as flexible or supple as some of the other materials that the tyre is made from so absorbs some energy. The more puncture protection then the slower the tyre is.
Length of Service
Governed by two things, thickness of the tread and the material. Thicker treads absorb more energy as they roll and hard-wearing materials are less supple and also take more energy to move them along.
Tyre can range in price from a few pounds to over a hundred. With more money comes better materials and more advanced features. Due to this more expensive tyres are also typically lighter than their cheaper cousins.
So why all this information you ask, well it allows us to have an informed discussion about the choices that you will have to make. Do you want a ‘shit or bust’ extremely fast racing tyre? A ‘impregnable’ training tyre or something in between. It’s a continuum between the two extremes and like most things in life we have to decide where we fall.
Why Should You Care?
Well quite simply tyre choice is one of the easiest places to save time in your racing, good racing tyres can save you minutes in a time trial or triathlon or make the difference between your breakaway making it or not. If you are a completer rather than a competitor then good tyres are simply more fun to ride and provide better handing and also puncture protection if that is important to you. People spend thousands on wheels and bikes and then handicap themselves with poor advice and bad rubber. How about an example? For info on Crr (rolling resistance) and Watts absorbed please see my previous post Tubulars vs Clinchers
Going from a basic tyre to a good racing tyre, we’ll use the data from a rouesartisales study and pick two common tyres (data given is for a pair front/rear).
Continental GP3000 – Crr = 0.0058, Watts absorbed = 46.6
Vittoria Open Corsa CX – Crr = 0.0039, Watts absorbed = 27.1
Data shown is for a steel drum, testing has shown that for a real rough road surface you can multiply by 1.3. So…
Continental GP3000 – Watts Absorbed = 46.6 x 1.3 = 60.58
Vittoria Open Corsa CX – Watts absorbed = 27.1 x 1.3 = 35.23
Using the rule of thumb that 10 watts will save you 40 seconds over the course of a 40km (25mile) time trial, or a standard distance triathlon bike leg for a rider traveling at 40km/hour shows us that
(60.58 – 35.23)/10 x 40 = 101 seconds just from changing tyres and pedalling just as hard.
This is all theoretical and you may find that you may save less or more in the real world but I hope I’ve shown what a difference it can make. For an Ironman which is 4.5 time longer the savings are even more significant!
101 x 4.5 = 454.5 seconds, getting on for 7 and half minutes!
So enough of the maths! What should I choose?
Right here’s what I would do, I would go and download the Bike Tech Review data. Pick a tyre from as far up the list (ones at the top are faster) tyres with an x in the tubular column are tubulars. Have a look at the manufactures info to find out how much puncture protection they have and make your choice. Race with latex inner tubes and train with butyl ones.
For training wider tyres are simply more comfortable so potentially go for 25mm if possible. For racing and aerodynamics sake then you should probably match the tyre width to the rim width. Modern rims such as those used by ZIPP and HED are designed around 21-23mm tyres. Check with your manfacturer to see if they have any recomendations. For example on my HED Trispokes I use a 20mm tyre up front and a 23mm on the rear where it’s less important.
In conclusion OR ‘But that’s not why I came here, so what tyres should I choose?’
For racing I would choose a Vittoria Open Corsa CX II, get the black ones, the compound they put into coloured ones slows them down. This is a thin, lightweight racing tyre with a fast tread material and has some puncture protection. It is a fast tyre and rolls very well when combined with a latex inner tube. They don’t last very long however and pick up small cuts in the tread. I also like them as they are very easy to get on and off the rim when needed.
For training and if you don’t have separate racing wheels and/or don’t want to change tyres on a regular basis before a race I would choose a Continental Grand Prix 4000s. This is a more robust but still reasonably fast tyre with good puncture protection. The tread is thicker, lasts longer and is more robust. Continental also do an Continental Attack/Force combo that has picked up good reviews. I haven’t tried them but am looking to get a set for my training wheels next. Will report in after a few thousand Km and see how they are doing. Continentals can tend to be a bit tighter on the rim than Vittorias though. When you buy a Continental Tyre get one with their Black Chilli rubber compound.
I have tried dedicated training tyres such as the Continental Gatorskin and didn’t like them, it felt as if I was rolling on hose pipe, however this is a very good tyre if you trying to avoid punctures. It has a thick tread that lasts a long time. It has multiple puncture belts and edge to edge slash protection.The ones I had were very hard to get on and off the rim though.
So there you go, three choices based on how fast you want your tyre to be and how much you are trying to avoid punctures.