This report is edited from material contained in issues 46 to 48 of Folding Society News. You can read the original reports by visiting our back numbers page.
PLEASE NOTE THAT THIS MATERIAL IS NOW QUITE DATED - the range and quality of tyres available to suit folders has increased substantially since 2000. Personally I find the recent Schwalbe Marathon Racer suits most of my requirements rather well, and it is available in most, though not all, of the sizes of interest to folder owners (notably I don't believe that there is a version which will fit a Brompton). The Schwalbe Stelvio is also available in most sizes. It is a high pressure high performance road tyre, but I find it rather fragile for normal use. 'Steve'. [05/01/2007}
Cycling should be a pleasure, even if it involves commuting or shopping. There are a lot of factors that can contribute to how enjoyable the experience is, and it is worth taking a bit of trouble to get things right. Tyres can play a major part in the performance of the bike, but as with most things, there are many factors involved, and some conflicting requirements have to be met. Light, narrow, high pressure tyres often result in low rolling resistance - which means less effort has to be expended by the rider - but against that they not last as long, may be more inclined to puncture, and may not perform as well on rough surfaces as wider, softer and heavier tyres.
Nearly all folders and separables use small wheels, primarily because it means that the bicycle can be smaller when folded. Unfortunately this means that our choice of tyres is very limited compared with the standard mountain bike (26in) and road (700C) sizes. Recently a number of new tyres to suit folders have been announced, or have already become available, so this seems a good time to review the situation.
First of all we should make some general comments about tyres and choosing the right one. Most obviously, the tyre to suit your bike must be the right size for the wheel, and this is best expressed by the bead diameter of the wheel tyre, where the tyre mounts. Usually the wheels/tyres are described by a nominal rolling diameter, eg 16 inches, but in some cases there is more than one bead diameter associated with the nominal size, and you can only fit the tyres with the right bead diameter. The second size factor is the width, usually given in inches (eg 1 3/8) or millimeters (eg 28). Generally narrow tyres run at higher pressures and have lower rolling resistance than wider (generally lower pressure) ones, but the wider ones give better grip (particularly off road) and also a more comfortable ride (partly at least due to the lower pressures). Views differ on the desirability of greater width - some claim that everything else being equal, wider tyres roll better, but as everything else is not usually equal, and most wide tyres run at lower pressures, I do not propose to get drawn into this debate either now or later. Usually narrower tyres have a smoother tread pattern than wider ones. For off-road riding wider tyres with a more pronounced tread pattern are generally better, though reasonable canal towpaths and bridleways can be negotiated with almost anything. It has to be said that for serious rough off-road riding larger diameter wheels and tyres are an advantage. When selecting tyre width, remember that on some bikes the brakes and mudguards may limit the largest tyres that can be fitted (wider tyres typically are slightly larger diameter than their narrower equivalents). Wider tyres with heavy tread patterns may also be more puncture resistance, though this is not inevitable. Many riders prefer the higher pressure narrower tyres for general use despite their disadvantages, due to the improved rolling resistance and more responsive ride and handling.
Suspension is more necessary with smaller wheels, to give a more acceptable quality of ride. Once fitted, it usually results in a better ride than a larger wheeled bike without suspension. It also means that using high pressures in the tyres to minimize rolling resistance does not have as much effect on ride quality as might otherwise be the case.
It is often suggested that most tyres are capable of being run at higher pressures than the rating on the side wall suggests. If you do this, then you do it at your own risk. Raleigh Records and AM Moulton Wolber tyres are both widely used at pressures of 50% or more above their rating, apparently without ill effect, but, on the other hand, some riders report the latest Birdy tyre blowing off its rim at the rated pressure, and are running them at below the maximum rating. A tyre blowing off the rim, or failing in some other way, could be fatal when riding, and indeed an explosion occurring during inflation could cause serious injury, so for obvious reasons we cannot suggest that you do it, or even experiment.
The scope for changing wheel and hence tyre size is limited on most folders and other bikes. 349 (16 inch) wheels have been successfully fitted to AM Moultons and to Birdys which normally use rather larger tyres, and this has been relatively simple (do not attempt this without a full understanding of the implications though). AM Moulton wheels and tyres have also been successfully fitted to a Birdy. Fitting larger wheels and tyres is, though, usually much more difficult, as it involves extending the fork dropouts, brake changes etc, and is complex, quite costly, and only to be undertaken by those who are brave and have both the knowledge and equipment required to carry out the modifications properly and safely.
For most owners, the choice of tyre will be determined by the original wheel size, but that still leaves many folder owners with some choice of tyre. The rolling resistance and ride quality of the tyre makes such a difference to the performance and feel of the bike that it is well worth taking into account when choosing a folder - some prospective owners might also wish to take into account how readily replacement tyres can be obtained, and for high mileage riders the tyre life and cost may also be considerations.
Now let's look at the different sizes and what is available.
For a number of years the only tyre available was the Raleigh Record, quite a respectable tyre with reasonable life and puncture resistance. However, the construction and low pressure mean that it does not roll very freely. The appearance of the Primo greatly improved the situation for users of this tyre size, as it is a high pressure 6 bar (85psi) tyre, with a fairly narrow cross section (1 3/8"), a light herringbone tread pattern and very supple construction. The Primo has a low rolling resistance and good handling characteristics. It is not an ideal off-road tyre, although reasonable towpaths and bridleways can be negotiated without difficulty, and it is probably more puncture prone than the Record, though not excessively so for a tyre of this type. Some riders have experienced sidewall failure after extended mileages, this preceding the tyre tread becoming worn out, and the tyre is certainly susceptible to cutting from glass. Those who have fitted Primos in place of Records have almost all been very pleased with the result – indeed, it is usually regarded as the biggest single improvement that can be made to a Brompton.
A new Schwalbe Marathon is now available in this size, and has pronounced tread, runs at a high pressure (up to 100psi) and has a Kevlar belt to protect against punctures. Those who have tried it have generally been impressed - good rolling resistance and good grip, and quite robust looking. It looks a good choice for those wanting better performance than the Raleigh Record, but also wanting something more robust than the Primo.
Two new tyres bearing the Brompton logo were launched March 2000. Both are rated at 6.8 bar (100psi), and the one has a Kevlar belt for increased puncture resistance, while the other is particularly reasonably priced at £9 each. At this time (April 2000) we have no long term test data available, but initial reports suggest that these tyres have good rolling resistance (comparable perhaps with the production version of the Schwalbe?) and perform well in other respects as well.
Overall, the position is very good for users of this tyre size, with plenty of choice of good tyres with some variety in characteristics - good rolling resistance, good puncture resistance and good life.
This size is exclusive to the AM Moultons (and a few belt-drive New Series Moultons). There is a very expensive (£50) racing slick, but this is hardly relevant to most owners, and the only other tyre is the standard AM-Wolber, which is rated at 5 bar (80psi) and has a width of 1¼ inches. This is quite an old tyre design, and by today’s standards it has quite a pronounced tread pattern, running around the tyre. Some owners complain that the life is not particularly good, and that they get punctures, but the majority of users find it is no worse in either respect than any other smaller tyres, and indeed it is better than most. In 15 years of Moulton AM use I have found the life is well over 1000 miles on the back, and much longer on the front, and punctures have been if anything less frequent than on my other small wheeled bikes. The rolling resistance of the tyre is good – surpassed, in my experience, only to the Continental Grand Prix 406 (20 inch), IRC 451 (20 inch x 1¼ ), and perhaps the 349 (16 inch) Primo. Off road performance, with the fairly substantial tread, is quite acceptable on better towpaths and bridleways, but not surprisingly it is not very happy on rougher and muddier surfaces. Although there is effectively only the one tyre in this size, I rate it as one of the best small wheel tyres – complaints by some owners are largely a feature of the fact that Moultoneers are inclined to whinge (at least some are). The one obvious problem with this unique size is availability of replacement tyres, though price is on a par with other high quality, high performance tyres.
This size is currently only used by the Riese & Muller Birdy. However, it is a moderately standard size for children’s bicycles, but the tyres intended for that market are of poor riding quality – they are generally rather wide, low pressure and with very poor rolling resistance and indifferent life. Therefore, except in emergencies, the range of tyres likely to be considered for use on the Birdy is more limited. The original tyre ran at low pressure, and had a high rolling resistance, and was the source of much criticism. Later a higher pressure tyre was introduced, with a fairly pronounced tread pattern not unlike that of the 349 (16 inch) Raleigh Record. Although rolling resistance was improved, it was still considered inferior to that of tyres like the Primo, AM-Wolber, and most of the good road tyres in the 20 inch size. Significant numbers of people reported very poor life as well, though my own experience has been quite good – over 1200 miles on the back, with a fair amount of tread still left, and over 1500 miles on the front and many hundreds of miles still to go. Puncture resistance seems reasonable. In addition to these tyres there is a low pressure wide, knobbly tyre for off road use, though its rolling resistance is poor on road. As the standard tyres perform reasonably well off road except in more extreme conditions, the knobbly is probably only worth considering if most of your riding is off road, and you look for muddy and/or very rough tracks. A new high pressure tyre has recently become available for the Birdy, running at 6 bar (90psi), and with a Kevlar strip to improve puncture resistance. I have been disappointed in the performance of this tyre - it is heavier than its predecessor, the rolling resistance seems higher, and one blew off the rim soon after fitting and inflating to no more than the recommended pressure. Another tyre which has recently become available in the UK is the Vredestein San Marino. Although this is rated at quite a low pressure, it actually rolls as well or rather better than any of the Birdy tyres, and it has a substantial tread and claims good puncture resistance.
The rather poor quality of Birdy tyres in the past has prompted a number of owners to fit different sized wheels, so that they have access to other tyres. The most common choice has been 349 (16 inch) wheels, with Primo tyres. This is a relatively simple change to make, although new wheels and tyres, particularly if new hubs, gears etc are required, is not a cheap solution. One person has fitted 17 inch AM Moulton wheels and tyres, and another managed to fit 20 inch 406 wheels and tyres, although this required drastic modifications. One of the main Birdy outlets in the UK, Avon Valley Cyclery, offers the option of a 16 inch wheel set when buying the Birdy, and can also make this available to existing owners. Given the wide range of good quality 349 tyres now available, this option is certainly worth considering.
The 406 bead diameter is by far the more common version of the tyres referred to as 20 inch, and is used by the Moulton APB and New Series (NS), most Bike Fridays (not the Rockets and other sporting versions though), and several other manufacturers. The greatest advantage of this size is that there are many tyres available, as this is the standard BMX size. Although many of the tyres are wide, knobbly low pressure tyres which are not good for road use, at least something can usually be obtained in an emergency, and there are also some excellent road tyres in this size. Note that some of the tyres are so large that there may be insufficient space to fit them on some folders and separables.
The highest performance road tyre in this size is the Continental Grand Prix, which is rated at 120psi, is 1 1/8 inches wide and has only the lightest of treads. This is the only tyre which can (officially) be fitted on the New Series Moultons due to clearance limitations. For very fast road riding it may be a good choice, but most users of this size tyre rate it as a bit too specialised and perhaps fragile for their purposes. After testing this tyre on some limited off road riding (varying quality cycle paths) I have to admit to being pleasantly surprised by its performance under these conditions.
Very close behind it in terms of performance are the Schwalbe City Jet and the 20 inch version of the Primo Comet. Both have achieved a very high reputation with users, and offer very good rolling resistance, satisfactory puncture resistance, good life, and responsive handling. Both have rather limited tread, and in the case of the Schwalbe the cross section is rather triangular, with a rapid roll off from the centre section. Neither is very suitable for serious rough road riding involving heavy mud and very rough surfaces, but they perform perfectly adequately on canal towpaths and reasonable bridleways. The City Jet was reputedly being withdrawn, but there seems to be sufficient demand to have ensured that they remain available, at least through some outlets. An interesting point for New Series Moulton owners is that the City Jet has been successfully fitted to one of these bikes, although the mudguard mountings required modification, and clearance between the mudguard and rear wheel is very small.
The later Schwalbe City Marathon is also rated as a god performer, though rolling resistance seems significantly higher than on the City Jet. Those seeking a rather more substantial road tyre for touring and gentle off road use would probably do best to consider the Continental Top Touring 2000, although there are some good (and not good) alternatives. The choice of wider, more knobbly tyres, is wider still, and I will not attempt to make any recommendations in this category.
As an aside, my personal view is that most bikes fitted with wheels of this size handle much more like conventional large-wheeled bikes than those with the smaller sizes, which have noticeably more sensitive handling.
This size is currently mainly used on the more sporting Bike Fridays, which currently include ‘451’ in the model name. It is significantly larger than the 406 size, at least in the case of road going tyres. The size has also been used in the past for some utility bikes. The current choice of tyre in this size is much more limited than the 406 size, although not bad by the standards of other small wheel sizes. The best performing road tyre for general use is undoubtedly the IRC Roadlite, which runs exceptionally freely and gives very responsive, but not over-sensitive, handling. It also seems to have good puncture resistance, and good life. This is not a tyre for serious off road use, though it will cope adequately with good towpaths and bridleways - rather like the 406-size Continental Grand Prix. I would rate this the best road performer of all the tyres that I have used myself. The other main options in this size are Primos, and I believe there may be one or two tyres more intended for off-road use. However, the Pocket Rocket and other sporting Bike Fridays are intended as fast road bikes, and clearances are somewhat limited, so the IRC is probably the best choice, with the Primo worth considering if you need something a bit wider and providing a softer ride – the unsuspended Pocket Rocket with high pressure IRCs does give a rather harsh ride. Recently Bike Friday listed a tyre under their own brand name in this size, though the description sounded remarkably like the normal IRC tyre.
For many years tyres were a problem for the owners of small wheeled folders - the choice was limited, and availability was a problem. Our choice is now much improved, and in the 406 (20 inch) size all tastes should be catered for. In the 349 (16 inch) size there has been a huge improvement in choice and quality of tyre, and for general road use owners should be able to find something to satisfy their needs. The other three sizes are also reasonably well served - a limited choice in the 451 (20 inch size) includes some excellent tyres, and though Moulton AM owners are effectively limited to the single AM Wolber tyre, this is a good performer. Birdy owners may still feel slightly neglected - quite a number of different tyres are available, but many of them have similar performance characteristics, and in particular none of them roll as freely as the best in the other sizes.
I have done a number of comparative road tests on several of the tyres mentioned. The tests were carried out simply by determining how far the bike would roll down a gentle incline followed by a flat stretch of road. Most of the tests were all carried out at the same time; there was very little wind, but on one slightly exposed part of the downhill part there did seem to be a slight wind blowing against the direction of travel. In most cases, each bike had only one run. A more rigorous test system would really have been preferable, involving several runs by each bike, and experiments with tyre pressures, but my enthusiasm on a rather cold day was not up to this. A few tests were carried out on different occasions, but in these cases one or more of the previous machines/tyres was included so that comparisons could be made without being influenced by changed weather conditions or other factors. The results were as follows, listing the bike which ran furthest first:
Bike Friday Pocket Rocket, 451 wheels, IRC tyres
Thorn Audax, 700C wheels, Panaracer Pasella tyres
Brompton SP, 349 wheels, Primo Comet tyres
Moulton APB, 406 wheels, Schwalbe City Jet tyres
Brilliant Micro, 349 wheels, Primo Comet tyres
Brompton T5, 349 wheels, Schwalbe Marathon tyres
Moulton AM7, 369 wheels, Wolber-AM tyres
Birdy Red, 355 wheels, Birdy 80psi tyres
Cross Micro, 349 wheels, Raleigh Record tyres
The Pocket Rocket outran the other bikes by a margin of several metres, but the next group of four finished almost exactly nose to tail. The T5 and AM finished just about equal, about 3 metres behind, and then there was a gap of about 5 metres to the Birdy and the old Cross Micro, which were more or less equal.
The nature of the test and experimental errors means that differences of one or two bike lengths should not be considered significant, so I would not try to read much into the differences within the 3 groups above. However, the Rocket on IRCs was clearly the best performer, and the Birdy, on the older 80 psi tyres, and the elderly Cross on the Raleigh Records, were clearly inferior to the others. The Birdy had reverted to the older tyres after my disappointment with the latest Birdy tyre, and tests immediately before and after changing back to the older tyres confirmed that the older tyre is worth about 4 metres on this test - which suggests that the new tyre would have given the worst performance if it had been included in the main test above. Unfortunately the New Series Moulton on Continental Grand Prix (406) tyres was not available for these tests - we hope to have some comparative figures for it soon.
These results are broadly in line with what I was expecting, although it was surprising just how big the margin in favour of the Pocket Rocket and IRC tyres was, and I expected the Brompton on Schwable Marathons and the AM to be right behind the main group, rather than separated from it by a few metres. Since the tyres were all fitted to different bikes, the bike itself could contribute significantly to the results, so it's worth commenting on this. The bikes with dropped bars were all ridden 'on the brake levers', with a minimum crouch position, while the others were all ridden with a very slightly hunched riding position - enough I think to minimise wind resistance differences. The Thorn, and more particularly the Brilliant Micro, are relatively new, and the bearings may not yet be running as freely as some of the others, while on the other hand the Brompton T5 is doing winter duty, and might benefit from an overhaul of the bearings. I made no effort to compensate for the different weights of the bikes - on this downhill rolling test, the heavier machines were at an advantage, so the performance of the lightest, the Brilliant Micro, was particularly commendable, while the heaviest, the APB, received help in this respect. One other factor which might contribute to the outstanding performance of the Pocket Rocket is that this is equipped with Campagnolo gears (not a Sachs 3 x 7), and it was the only bike with Campagnolo hubs.