The Birdy uses an 18inch tyre, which is not a common size in many parts of the world, although it is claimed that in its home country, Germany, it is a well established size. When the bike was introduced it was rumoured that it had originally been intended to use the 17inch wheel and tyre combination which is fitted to Alex Moulton AM bicycles, but that AM had refused permission for this (only a single tyre is available for this format, and the tooling is owned by AM, although the tyre is manufactured for AM by Wolber/Michelin). Although the rumour is plausible, there is no evidence to support it, and neither AM nor Riese & Muller have ever confirmed the story.
.Whatever the reason for the use of the 18 inch tyre size, it does present problems for owners. When the Birdy was originally introduced it used a low pressure tyre marked as 35psi and with the brand name Cheng Shin. This had relatively high rolling resistance, and compromised the otherwise excellent performance of the bike. A knobbly tyre for off road use did not solve this particular problem, and the release of a higher pressure tyre was eagerly awaited. When it came, it was a serious disappointment. This tyre is marked as being suitable for use at 80psi, and carries the brand name Birdy. However, even at the higher pressure the rolling resistance is disappointing, and life is very poor. Many people have reported under 500 miles from one of these tyres on the back. My own bike has now completed 600 miles with the same tyre on the back, but judging from the wear so far it is not going to last 1000 miles, and this is on a bike which is ridden gently by a light rider (under 125 pounds). The problems with the tyres have led some owners to convert to 16 inch or other wheel sizes. In the UK the Birdy high pressure tyres cost 12.95 pounds each, and although they seem relatively cheaper in the USA and Germany, this still makes running costs high. At least as undesirable is the fact that the tyres are not easy to obtain due to the limited number of dealers.
What we really need is a Primo tyre in this size (the 16 inch and 20 inch Primos have an excellent reputation), but at present there is no sign that this is forthcoming, so the best advice is to expect a relatively short life from the tyres, and to make sure you have spares in stock for when they are needed.
The following information regarding new tyres and some changes in specifications were posted to the Birdy email list on 9 September 1999 by Thorsten of sprl VELODROOM bvba, Brussels (velodroom@hotmail.com).
With a Birdy Green which we received recently there was the new r+m catalogue for the next season. There will be a new tyre with the following characteristics:
So the rumors have been correct. I have no information regarding the price yet.
Some bike specifications have changed:
The rest stays more or less the same.
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