The Moultoneer Issue 63, December 2001 – some additional thoughts and information Updates

Updates

  • The web site is now located at http://www.moultoneers.net. Please makes sure you use this address in future, as the old site at Demon will become unavailable after Christmas.
  • Graham McDermott (« In the Press ») has now moved to 32 Avon Close, Bradford on Avon, Wiltshire BA15 1JJ. email: graham.mcdermott@btinternet.com

Continental 17 inch tyres

I’ve covered some more distance on the Continentals since the report printed in The Moultoneer appeared. I’m still using the same pre-production tyres which Shaun Moulton kindly gave me to try just over a year ago. Obviously the recall of the first production batch was both disturbing and inconvenient for many people, but it was to the credit of both Moulton and Continental that they did formally recall them, rather than just wait for individual owners to complain and return any which were faulty. I remain very pleased with the set I have, and despite this upset they will remain my tyre of choice for the 17 inch wheeled models.

Other tyres

A Schwalbe for the New Series?

The news contained on page 4 that a new Schwalbe ‘Stevlio’ may become available in 28-406 size, which will fit the New Series models, is very welcome. We had heard some rumours of an un-named Schwalbe ourselves, and reported this on the web pages. In view of the limited clearances on the NS, it is inevitable that this would not be a very heavy duty tyre, but the description of it as a slick is rather disappointing – I think that what most NS owners were hoping for was a slightly more substantial tyre than the Continental, even if the clearances meant that the difference would not be very great. Nevertheless, more news on this tyre is eagerly awaited, and as soon as we get any information we will report it on the web pages.

16 inch (349) tyres

Owners of the older F-frame Moultons with 16 inch wheels are now spoilt for choice  of tyres! The old Raleigh Record was for many years the only tyre available, and it proved quite a suitable tyre for general use. However, the several newer tyres in this size which have become available in the last 3 or 4 years do offer significant improvements in performance, especially rolling resistance, as referred to by Michael Woolf on page 22. The Primo Comet almost certainly is the most free running of these tyres, but it is a bit prone to becoming cut by glass, and the rather thin side walls (which of course contribute to its good running characteristics) can wear, even when maintained at the correct pressure. The minimal tread does also make it necessary to be careful in some conditions. The Brompton tyre is available in two forms – with and without a Kevlar lining to increase puncture resistance. Tests by A to B suggest the non-lined version runs more freely, and it is a lot cheaper. Kevlar linings do not by any means eliminate punctures, so the unlined version may be better unless you are convinced of the benefits of Kevlar. Where I would like to take issue with Michael is on the subject of the Schwalbe tyres. I’ve been running these on a Brompton for a couple of years, and I find they offer very good grip, long life and reasonable puncture resistance. They do not roll as freely as the Primo, but they are very good nevertheless, and their more robust construction with a substantial tread makes them more suitable to my mind for the sort of urban and towpath riding which I use that bike for. There have certainly been reports of some of these tyres failing in the way that Michael describes, but I and others have had no problems, and I understand that the problem has been overcome. I think that just because of an example of a failure I would not rule them out – on that basis, the new Continental 17inch would be ruled out as well. Even more significantly, given the failures of forks on the earliest Moultons, we wouldn’t ride those either! There are precious few manufacturers (in any industry) who have not had a problem with a product at some time, and the ones which haven’t had one yet, and say they never will, are either exceptionally clever or exceptionally brave to make such a claim. As for Bridgestone, after their experience in the USA with (motor) tyres supplied by Ford …. Michael was of course put off the Schwalbe by rolling resistance as well as the split. I reported on some tyre test in Folding Society News issue 46 and issue 47. In the tests I carried out the Schwalbes performed pretty well – in fact they out-ran the old Wolbers on the AM, although the Primo did quite a bit better. Although I have had a set of Brompton (Kevlar) tyres for some while, I have not done a direct test against the Schwalbes or anything else – I planned to fit them to my SP, but lack of clearance at the back means that this has still not been done. For urban use, towpaths etc, personally I’d still be inclined to go for the Schwalbe because of the more substantial tread, good grip in the wet, and the very good life which I am getting from them. The Bropton would be my second choice for this sort of riding, with the Primo being the winner where its lighter construction is not an issue.

Chain Throw

Chain throw has been a problem for many owners of AM7 Moultons since they were introduced in 1983, and Arthur Smith’s article on page 25 provides useful advice on setting up the system to minimise the problems. I’ve owned an AM7 since early in 1984, and have spent much time in the past trying to ensure the correct chain line and altering chain length as described by Arthur, and I have to say that I never managed to eliminate the problem. When the bike was converted to AM8 specification by the factory, I hoped that the problem would disappear; well, it was certainly better after the conversion, but it still threw the chain off sometimes – usually when changing into top gear, but sometimes even in an intermediate gear.

It’s important to put this in perspective – it’s not just a Moulton problem, as I’ve experienced the same thing with other bikes with a single chainring and 7 or more sprockets on the back.

When the New Series was introduced it followed Dr Moulton’s preference of having a single chainring, like the AM7, AM8 etc, and there were reports of chain throwing again. We’ll come to the solution in a moment…

So why is the chain thrown on these machines and not others, and what is the solution? Well, the key thing about a single ring system is that there is no changer mechanism at the front – if you have a front changer mechanism, then the side plates restrain the sideways movement of the chain during (rear) gear changes. It’s no accident that most bikes fitted with the Sachs/SRAM 3 x 7 or 3 x 8 gear system, with only a single chain ring, have a plate on the outside of the ring – it not only stops the rider’s leg getting oily, but more significantly provides some restraint for the chain at least in one direction. Birdys have two plates, one either side of the chain ring – probably mainly to keep the chain in place during folding, but they also serve to restrain the chain during gear changes. Of course the AM 7  had a simple plastic plate of this kind,  but it was a bit flimsy, and if removed to work on the bike, it was difficult to refit it, so it was often omitted.

lThe best solution to the problem of chain throw can be found by recognising the value of the front changer as a chain restrainer during rear gear changes, and that is the solution that Moulton themselves have applied now. Apart from early machines, singe chain ring New Series bikes have been fitted with a ‘chain keeper’. This is a simple pronged device which can be clamped onto the uprights of the rear fork, and restrains sideways movement of the chain. A version is also available for the AMs, and I fitted one to the AM7 (in 8-speed form) and it completely eliminated all the past problems I had experienced with chain throw. Quite a lot of work is involved in the manufacture of the Moulton keeper, and it is stainless, so it is not particularly cheap, but most owners could probably achieve a similar result with a couple of strips of bent metal and a bolt.

One of the most interesting things I have found since fitting the keeper is that you can quite frequently hear the chain bounce against the keeper during gear changes. This shows both that there is often quite a lot of thrashing of the chain sideways during a gear change – usually it is difficult to watch the chain while riding, and anyway the sideways movement is very fast – and that the keeper is doing its job. Given that part of the problem is not just the actual alignment of the gears, but also the amount of thrashing, I think that fitting a keeper is the best solution to chain throwing on a bike with a single ring – though of course correct alignment and chain tension are still important.

If you suffer from chain throwing on a Moulton AM7, or other derailleur geared machine with a singe chain ring, I’d suggest fitting a chain keeper. The one produced by Alex Moulton Bicycles fits extremely easily (just a bolt and a large knurled knob), but most owners could probably put something equivalent together for themselves. On a non-Moulton, without two rear triangle tubes to mount on, an equivalent device may not be quite as easy to devise, but should still not be too difficult to achieve.