Due to the oddities of actual versus nominal wheel sizes, the overall diameter of what is referred to as a 16 inch wheel and tyre is only slightly smaller than that of the Birdy wheel and tyre, which is referred to as an 18 inch - the difference is fractions of an inch, not the 2 inches that the names suggest. The 16 inch size is fairly standard, and although the range of tyres available in this size is not very great, it includes the superb 16 x 1 3/8 inch Primo, which offers very low rolling resistance, a good ride and reasonable life. The tread on this tyre is very light, so although it can cope with canal tow paths and bridle ways, it isn't suited to serious off-road work. The more utilitarian Raleigh Record is another popular tyre in this size, although it has less to offer over the Birdy tyre, apart from better life.
A to B Magazine (1) has mentioned briefly that they converted a Birdy Green to 16 inch wheels with the Primo tyres, and I have also seen other Birdys converted in this way. One of these, the Red belonging to Paul Stobbs, showed an alarming front wheel shimmy, although this probably had more to do with the poor build of the wheel than any inherent problem of the different wheel/tyre. Avon Valley Cyclery (2) were at one time offering a conversion set consisting of the parts necessary to make the change to the 16 inch wheel.
An attraction of this conversion - apart from the better availability of tyres and the better ride offered by some of these - is that it is apparently quite simple (no more than replacement of the wheels and tyres) and not too expensive. On the down side, you could but a lot of Birdy tyres for the cost of the conversion (though you would of course still have poor rolling resistance) and the range of tyres is still limited, even if it does include the superb Primo and the reasonably rugged Raleigh Record.
1. "The Trial: 3x7", A to B magazine, Issue 3, December 1997, pp 23-27
2. Avon Valley Cyclery Ltd, Bath Spa Railway Station, Bath, BA1 1SX,
England
Tel: 44 (0)1225 442442/461880
Fax: 446267
Web: http://www.foldingbikes.co.uk
From Dr Simon Batterbury, Simon.Batterbury@Brunel.ac.uk
1. Phoenix Cycles (59a Battersea Bridge Rd, London SW11, 0171 738 2766) converted my Birdy to 16" wheels in September 1998 as follows.
a) supply 2 new Brompton rims and Primos (supply rims £30.00, tyres
£30.00)
b) supply a 28 hole front hub , which makes life easier (£20.00)
c) additional spokes (£5.25)
d) wheel rebuild (£45.00) including making my 36 hole rear hub work
with the Brompton rim by drilling extra holes in the rim.
This has resulted in a a rock solid rear wheel. The old inner tubes were retained. One problem is that my early model has side pull brakes. These did not reach to the slightly smaller rim size. An old set of 730 Weinmanns off a racer were fitted instead (10.00 s/h) but there are probably better options available. Not a problem on newer Birdys. Rolling resistance is dramatically improved, and braking is better. The bike sits minimally lower to the ground and gearing is minimally lower.
2. If the pins fall out of your handlebar hinge, go to a car shop and get the nice strong pins that are used to join the push-pull gearstick of a Citoren 2CV to its gearbox. They are stronger, have a proper circlip, and work with the addition of a couple of washers.
3. A Birdy can be 'wheeled' in transit - just open out the front wheel, grasp the partially folded bike by the saddle, and wheel it along with the front wheel trailing. Useful underground on Tube connections, for example.
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Last updated: 13 February 2000