Tyre Buying Guide
As with tyres on cars, tyres on bicycles are crucial for safety, reliability and comfort. And as with car tyres, different tread patterns are needed for different applications. The trend for increasingly wider tyres meaning that the choices are becoming bewildering. However, there are a few basic things you need to know that will help you easily navigate the complex world of cycle rubber.
Size is important
As with frame sizing, wheels on road bikes are measured in cm and on mountain bikes they are measured in inches. Just to add to the challenge, Hybrids have frame sizes usually measured in inches but they have tyres and wheels measured in cm. It is therefore crucially important to know how to check your wheel and tyre size. Don’t forget though that your frame will also dictate how large a tyre you can have. If you have a hybrid bike or a road bike fitted with cantilever brakes and mudguards, chances are you going to be restricted in what you can fit with respect to your tyres. Always check the specification of your particular bike before upgrading your tyre size.
Check the sidewall of your tyre. You will find the size of the tyre clearly printed. If it says 700 x 25c then you have a 700mm wheel with a tyre that is 25mm wide. Note, even the 700mm is slightly approximate due to some tyre manufacturers having slightly taller or shorter sidewalls. Note also that on a mountain bike, you are going to have a wheel measured in inches. This will either be 26”, 27.5” (also known as 650b) and 29” (29er).
Road Tyre Size
Not so long ago, pretty much every road tyre was 700c x 23c and that made life fairly simple. Not so any more. Now, 25c, 28c and even 32c are increasingly common. Why is this? The tyre manufactures say a wider tyre reduces rolling resistance and therefore saves energy plus they are more comfortable. It seems the frame manufacturers agree because frames are becoming ever more generous in their clearances to accept these bigger tyres. Not everyone agrees because there are some potential aerodynamic and weight disadvantages of wider tyres to be taken into account. But the trend is clear – the pros are using wider tyres and that inevitably means the bike manufacturers will follow suit.
Mountain Bike Tyre Size
Mountain bike tyres also come in a variety of widths including Fat Bike tyres and Plus Bike tyres. Tread patterns also play a significant role with mountain bike tyres. The type of terrain you will be predominantly riding over will to a large extent dictate the tread pattern best suited to your needs. If your focus is Cross Country, then a lower profile tyre will probably suit best. These are good on hard pack surfaces with a lower rolling resistance. However, the smaller knobs on the tread pattern will get overwhelmed more quickly in deeper mud than a tyre with a larger, deeper tread knob pattern. If your focus is Downhill, then the larger tread knobs on both the centre tread and the side tread areas will ensure the tyre bites in really well with excellent braking performance and excellent grip in turns.
The really critical things though when choosing mountain bike tyres are:
- Correct Wheel Diameter
- Width (there needs to be sufficient room to get your tyre between the forks / brakes / stays)
Fat Bikes initially became popular for riding on snow and really loose material, providing plenty of grip even in the most extreme conditions. However, the fashion for Fat Bikes has really taken off with Fat Bikes an increasingly common sight at trail centres around the country. Pedalling from a standing start and getting up to speed can require a bit more effort than a more traditional trail bike and the feedback is slightly less with the big fat, lower pressure tyres absorbing much of the undulations in the trail. But get a fat bike up to speed downhill and it’s 100% maximum fun. You’ll flow through those berms like never before with a smile nearly as wide as the tread on the tyre.
The most recent addition to the mountain bike tyre glossary is the Plus Bike. In principle they offer the ability to run wider tyres (e.g. 3.0 inch) over standard (2.3 inch) on a wider rim (typically 40mm wide compared to 25mm). Thus a 27.5+ tyre ought to give similar benefits to a 29er in terms of rolling radius with greater tyre contact patch and therefore grip. The wider and deeper tyre also can run lower tyre pressures thereby giving a more confident and compliant ride. Customer feedback has been overwhelmingly positive.
Beads – Folding or Rigid
The bead of the tyre is the stiff edge of the tyre, usually made of steel or composite, that hooks onto the rim to keep the tyre firmly seated on the rim of the wheel. Two options are available:
They are less flexible meaning they can be a pain to carry around or store. They do however tend to be a bit cheaper.
The advantages of being light and easy to store however does come with a price penalty compared to rigid beads.
Valves – Presta or Schrader
The valve of the tyre is where you attach your pump to get into the tyre to inflate it. Valves come in one of two types:
These valves are tougher and more reliable. Schrader valves are similar in design to those you will find on your car. Amongst their advantages are that they are extremely resilient and are really difficult to break plus you can remove the inner core if something does go wrong and replace it. The downside of them is that partly because of this inner core, they are wider and therefore require a larger hole through the rim of the wheel. That’s not very good because holes in the rim are one of the principle causes of weakness of the wheel. Tyres can also be slightly harder to inflate when they have Schrader valves because of the need to activate the spring on the inner core of the valve.
Presta valves on the other hand are narrower and easier to inflate, not least because you do not have to deal with any spring on the inner pat of the valve. However, because they are narrower, they are more delicate and if you damage the valve, you can’t always replace it – you may have to throw away not only the valve but the inner tube as well.
The whole question of whether to go Schrader v Presta is something of a moot point however. If you have a road bike then you will almost certainly have Presta valves but if you have a Mountain Bike, you will have a choice of either. However, it will be rim specific. In an emergency, you can always get a presta valve through a rim hole designed for Schrader valves but not the other way round.
The most important thing? Buy a track pump that has a valve attachment that will work with both thereby rendering it pretty irrelevant whether you have a mixture of the two valves. Do note however, that if you have a wheel rim that has a deep dish (perhaps a carbon dish such as a Bontrager Aura wheel) you will need to buy an inner tube that has a long valve otherwise it may not be long enough to sit inside the carbon dish and still protrude far enough for you to be able to attach a pump and inflate the tyre.
Pressure is measured in good old fashioned imperial psi (pounds per square inch) on bikes. Each tyre will have its own minimum and maximum recommended tyre pressures and it is important to ensure you stay within these parameters when inflating your tyres.
In terms of which Tyre pressure also dramatically affects grip and comfort as well as puncture prevention and rolling resistance. For example, if a road tyre has a minimum of 80 psi and a maximum of 120psi, if a rider of 90kg riding on rough tarmac inflates the tyre to the minimum 80psi then the rolling resistance and risk of pinch puncturing will be materially higher. However, if the same rider on the same road inflates the tyre to the maximum 120 psi then the tyre will feel significantly easier to reach and maintain a higher speed. But the vibrations felt through the bike also be significantly higher.
In summary, tyre pressure is a constantly evolving process based on a balance of your weight, comfort requirements and performance. We recommend starting with the mid point between the minimum and maximum pressures of your tyre and increase or decrease the pressure by 5 psi increments / decrements until your own ‘sweet spot’ of comfort / grip is achieved,