Rim & tyre dimensions.

What tyre size do you want?  Bikes used for racing need thin tyres. Hard-core downhill MTB folks want fat tyres. But most of us fall in between. For long distance tourers, rim and tyre dimensions end up being a big issue. On a recent test ride in India there were four VWRs plus one flat-bar road bike fitted with light 28C tyres. This last bike got all the punctures. Five in 1,400km. Also it had to go much more slowly on the few days of bad roads.

Added to the issue of width (cross section) is that of diameter. Many people accept the proposition that 700C rolls better than 26” simply on the basis that 700C is a larger circle and therefore road bumps must seem “smaller” to it. Bumps can be “rolled over” more easily.

In the mountain bike scene, wheels were 26" but in recent years there has been a move to increase this and there are now 650B and  29ér sizes. 29'ers are actually 700C with another name. The idea behind the recent upsizing of MTB wheels is the idea that bigger wheels roll better.  However, research does not absolutely bear this out (see Bicycle Quarterly, Vol.9 No.4 Summer 2011 “Do Larger Wheels Roll Faster?”). If we are measuring energy input for a given tyre width, the small difference in diameter between 26" and 700C is less significant than tyre pressure differences. But there are other issues too.

Width issue.

Narrow tyres may be (and need to be) inflated harder than wider tyres and harder tyres roll more easily. They are normally lighter requiring less rotational force to accelerate and they have less air resistance. Whilst a bike commuter and tourer does not want heavy tyres, they also do not want hard/rough tyres. And most of us will put up with slightly slower tyres as a trade-off against punctures.

Narrower tyres wear out fast and on a tour this may require you to carry spares, offsetting some of the benefits.

Also, narrower tyres must be kept hard as it is a smaller volume of air keeping you up. Pumping tyres up frequently is a chore. They generally puncture more easily. If you ride for several hours a day the hardness of the tyres is key factor in whether or not you get a sore behind.

Tyre choice is about trade-offs and you don't want to err on the "too light/narrow" side.

Some people imagine that bike touring occurs on rough or sandy tracks requiring fat, rugged tyres. But in reality, most cyclists actively avoid soft, sandy surfaces and absolutely avoid mud. Those conditions are simply too exhausting plus they can easily result in harm to the drivetrain. The chain, rear derailleur and cassette, are rapidly worn  when sand or mud are on them.  Full chain covers and internal hub gears can cope with some mud and are better for those environments.

Bike tourers don't seek out bad roads for the heck of it.  It is more a case of there being occasional bad bits of road which you need to survive without damaging a rim. You may want to get “away from it all” but you dont't want to suffer. And you don't want to break something on your bike.  Damaging a rim on a tour presents a serious problem, especially in remote places. Lightweight rims are not recommended for loaded bikes anyway.

Summary so far... Diameters could be 26" or 700C. The tyre model needs to be in the tougher/heavier end of the spectrum. Keeping the tyre pressure up (eg above 60psi) make for less work. For touring mostly on roads, cross sections in the 32C-35C zone are good. On bad roads tyres need to be a bit wider (38-40C).

The best quality roads are generally in areas with more people and traffic. But they are busy. We seek out quieter places and these are where roads are sometimes neglected. Here are a few examples in NW Tamil Nadu (India). Whilst sections like this slow you down, they are fine if your bike is designed to handle them. There is a lot of slowing down and then the need to pick up speed.  Over a longer stretch you’d get sore on high pressure tyres. Added to the higher probability of punctures, high pressure tyres on really rough roads are not a good idea.  Using a bigger bag tyre allows you to run lower air pressure.

Meanwhile, there are many great touring routes where you can tour on 80psi tyres. You move faster and use less energy. So 32C or even 28C for may be ok if you happen to know the route and road surface in enough detail in advance.  Below on the left is a shot in Iran. Iranian roads are amongst the best in the world. To the right is a shot on the Pampas in Argentina. However these are just good sections and it is not all like that! You can carry spare tyres and swap them to suit roads but it means more luggage.

Many roads that are not sealed but still don’t require fat tyres. The shots below are taken within a few k’s of each other in Costa Rica. Fat tyres would be no particular advantage here. Sometimes you need to get off the bike regardless of what tyres you have so as to ensure that you don't get mud on your chain.

Diameter.

On the diameter issue there are more tyre and rim choices offered in 700C (bead seat diameter of 622). In the 32-35-38 widths the available range is big. It is far bigger than the 26" range in those widths. In recent years the range has grown even more due to growth in specifice E-bike rim options and the so called 29'ers in the MTB world. Except for short riders needing frames where 26 (bead seat 559) in1.4"can be used, 700C"suits our body sizes quite well.

It is sometimes said that there is better availability of 26" spares in for example South America. Certainly there are plenty of places where 700C is hard or impossible to find. However we do not generally design modern long distance touring bikes on the basis of availability of spares in certain parts of the world. If we did we would not have disc brakes, 9 speed derailleur gears or clipless pedals.

Tourers choose tyres and spares for a particular trip. There are some remarkably durable ones. Rear tyres wear a bit faster and the pair can be rotated. This adds up to the tyres on a new VWR with Schwalbe Marathons having a range of 12,000. In Australasia, East Asia, Europe and North America there is no need to carry a spare due to wide availability. On trips of less than 10,000km there is no need to carry a spare.  A good spare in the situations where it is wise to carry one, is the foldable Vittoria Randonneur Pro in 700x32 which weighs only 420 gms.  

From sheldonbrown.com.

Most owners of VWRs play around with their tyre sizes a bit. But our choice for production is 700x35C. Schwalbe Marathons are close to puncture proof. They are very long wearing and can be inflated to 80psi. On good roads, at these pressures, they will roll well. But, subject to loading and speed, the rims are still safe if these tyres are run as low as 45psi.  Hence we base all of our bikes, except for the extra small frame size, around 700x35C tyres. Although VWR bikes are made to ride primarily on roads (as distinct from mountain bike trails),  they are expected to be ridden on some dirt.

This shot was taken from a 700x35C World Randonneur on a ride with 26x1.75 mountain bikes on mostly rocky trails in mountains in Iran. 700x35 is not the choice if this is all you ride on but if you are on a tour and just want to do a section like this you will be fine. 

Touring in the city - what tyres?

Our design brief has always been to make long distance touring bikes that are also ideal for everyday work in cities. There is a close correlation between the situations. Carrying luggage as you travel by bike or doing your grocery shopping on the way home. Needing to be ready for all conditions ...possible rain, some riding at night, and sometimes needing low gears.

What are the issues for bike tyres on commuting bikes? That depends on your route which could be free of traffic, well swept and well drained. But in most of the inner city areas we see, there are not enough separated bike paths to allow you to always avoid riding on the roads.

After rain the edge of the streets, where we mostly ride, can be hazardous. Fine bits of glass, tiny bits of wire and other rubbish. Wet slippery leaves, wet metal grate covers and wet white line markings. Pools of water that you don't know the depth of. You should have rugged tyres on your bike.

If you are fit enough to keep up with the traffic you can ride in the middle of the lane but most of us are not willing or able to do that all the time and weasometimes are in the zone near where the gutter meets the tarmac. From above, where we are looking from, it is hard to tell if there is a smooth transition or a 1-2cm difference in heights. You would not go there on a thin-tyred road bike but a touring bike can handle the edge of the city roads.

Reliability of their transport is an issue for all city commuters. You don't want to be late just because you commute by bike. Infact, as with walking, cycling allows you to predict your arrival time within a few minutes.

We use a heavier rim on the rear (left drawing). It is 580gms whereas the front is 510gms. The rear wheel has more weight on it. The front wheel (right) has a disc brake so does not need to stay as true and gets no rim wear from the brakes. In an emergency the rims are are interchangable. Both are 36 hole.

Saving a damaged tyre.

If you are on bad roads carry a tyre boot or sleeve (a patch for the inside of the tyre). If you see a tyre starting to burst out, the boot, made from something the weight of a motorbike tube, can safe the tyre. The paces you might want to do this are those, such as Sth America, West and Sth Asia and Africa, where 700C is uncommon.

The tyre wall on the left started to fail due to high pressure combined with a very rocky track on the western ghat in India. At the first town the motorbike shop guy cut up a scooter inner tube and wrapped it completely around the bike tube. It took him a minute and completely solved the problem.

Because we are on the ground travelling slowly we can easily forget that things can be sent to us by air courier. Watch out for customs problems in some places. The major couriers and and the big on-line stores are able to get the customs documentation right.  

Rim wear.

Of interest to long distance tourers are the remarkable lengths gone to by some rim makers to prevent rim wear. Rigida in Europe makes a rim which is blasted with tungsten carbide in a way that fuses it to the rim and presents a very long wearing surface (providing you only use a particular brake block). We have been road testing them and they are good, but very expensive and also heavy. Rigida Andra CSS rims weigh 735gms each. Adding a gram to the outer part of a wheel, due to the need to accelerate it, effectively adds 3 grams to your bike weight. For a very long trip such as 50,000+km, this is an upgrade worth considering.

On our set-up you should find your front rims will last indefinitely and rear rims 15-25,000k depending on the amount of braking (which is more in city riding) and your all-up mass. To get the best life out of the rear rim, keep the brake shoes free of grit. Grit that collects in the shoes will abrade the rim. Occasionally you should lightly file or sand the rear brake pads to remove any abrasive material.

Rim failure and notes on heavier rims.

If you are 95kg+ and carrying weight on the rear rack there is increased risk of damage to the rear rim. This is unrelated to the sidewall-wear problem arising from rim brakes. A heavy pothole impact can momentarily push a section of rim inwards. As it springs back the high spoke tension on the right side nipples can result in a section of right-side eyelet surrounds cracking away from the rest of the rim. If that happens you might get another 500k out of it but that rim needs to be replaced.

The solution is to avoid it happening by not hitting things hard if you are heavy (in combination with the load).

There are some places where the roads are so bad (Bolivia is an oft-mentioned example) that it is hard to protect rear wheels on heavier setups. Carry some luggage on the front. Use 40C tyres and keep them up at about 70psi. This allows some absorption in the tyre.

A heavier rear rim will help but we already fit a 580gms rim to the rear. There are not many that are much heavier. Sun used to have a Rhyno at about 800gms but discontinued it years ago. Now they have a Rhyno-Lite at 590gms. There is the Rigida Andra CSS at  735gms.