Classic Lightweights UK
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Constrictor Conloy rims

Author: Hilary Stone
Constrictor HS 1
These days we rather take for granted the light and strong rims we use on our bikes. Surprisingly, a small factory in East London, the Constrictor Tyre Company was responsible for the first truly modern light aluminium rims which were introduced seventy years ago. As the name implies Constrictor started off as a company specialising in tyres back just after the turn of the 20th century. A little while later they were bought by Leon Meredith – and those who have read the Design Classics may remember him as the importer of the then revolutionary Bastide bicycles. In 1912 they began offering a steel wired-on rim with a hollow box
Consrictor HS 2section (Image left) which apart from the material is still very modern looking in appearance – crescent, almost aero shaped. These rims were popular with the top riders for they were strong and relatively light and featured a proper braking surface unlike the commonly used Westwood rims. They were available in several finishes including a painted ‘wood’ finish - apeing the wood sprint rims of the period which were similar in shape. Combined with a narrow Constrictor tyre these looked much like a full-on sprint rim with tubular tyre and were not much slower.
The story of the Conloy rims starts a little later – in the late 1920s several companies started to experiment again with aluminium cycle components. Rims, pedals and even frames had been made before but had not been popular with serious hard riders. Constrictor were one of the more adventurous and in 1927 launched a whole series of bicycle components – cranks, chainwheels, hubs, pedals, toeclips and rims under the Conloy brand name and were awarded the CTC Plaque for the greatest improvement to cycling with their Conloy products. The cranks and pedals were only listed for a couple of years or so but the solid section rims with a very similar crescent aero shape to the steel ones they already made were a great success. Constrictor imported most of these aluminium components from France but in 1933 import duty was radically increased and Constrictor looked to source components in England. Pedals and hubs were now made by BSA for Constrictor. And by 1934 the rims began to be manufactured in-house. They were now of a hollow section, still with the crescent-aero shape made from an extruded tube reshaped and rolled into a spiral to be cut to the correct length before being joined with a steel plate. Constrictor were now able to offer rims in any diameter and drilling but the vast majority were 26 x 1¼in which was pretty much the standard wired-on size for lightweight bikes in the 1920s and 30s.
Constrictor HS 3
Sometime during 1935 Constrictor introduced a new version of the hollow rim which was just a little narrower and a little lighter. This was the classic Asp rim (image right).
Now all Constrictor crescent shaped rims are often known as Asps but the name was reserved for the narrower section rims. At about the same time Dunlop introduced a new wheel size, the 27 x 1¼in (630mm bead seat diameter) which was not related to any other size. Constrictor soon offered the Asp in Dunlop’s new size as well as the two common 26s and what Constrictor called continental 27s – what we know as 700C.
Constrictor HS 6

Constrictor Asp rims continued through the 1930s, 40s and 1950s and were rated as the best available. As cycling declined after petrol came off ration in 1953 a plethora of models was introduced in an effort to stem the decline in sales. But Constrictor had rather lost its way with many new products which were just not innovative enough. And many new good rims were beginning to come in from the continent. Constrictor finally closed its doors in the late 1960s.


1912 Introduction of hollow section crescent shape steel rims
1927 Conloy 26 x 1¼ and 26 x 1 3/8in rims
1930 Light Conloy version introduced alongside what was now called the Medium Conloy
1933/4 Hollow section Conloy rim introduced
Late 1935 New Narrower (7/8in wide) Asp rim
1936 Asp available in new 27in Dunlop size
1938 Steel hollow section crescent shape rim introduced
1948 Boaloy solid section aluminium rim with flatter shape weighs 24oz (650g)
Asp available in two weights 14oz (380g) and 17oz (475g)
1951 Mamba solid section rectangular shape aluminium rim introduced; weighs 18oz (490g)
1954 Cobra hollow section, half round shape and less deep well than Asp; weighs 16oz (430g)
1955 Supalatti solid section slightly rounded shape with flat braking surfaces; 19oz (510g) with metal badge
1958 Viper solid section slightly rounded shape with flat braking surfaces with notched joint; 19oz (510g)
1962 Brillani hollow section rim, slightly wider than Asp, half round shape;17oz (475g)

Use Westwood rim washers under the spoke heads when building wheels with the hollow section rims.
Originally an extra thick cotton rim tape was available for the Crescent and half round rims; these days use two or three cotton rim tapes to fill the well. Tyres are very easy to fit and remove but need care to be centred correctly.

Constrictor HS 5