Alex Singer Bottom Bracket

The French 'Constructeur' Alex Singer was known for many custom parts. Some were standard items found in similar shape on many bicycles, like his fillet-brazed stems and rod-actuated front derailleurs. Others were rather unique, like his cam-actuated brakes. His bottom brackets were a major improvement on the then-standard items, and his approach showed his independent thinking - so independent in fact, that he sought and was awarded a patent for his design Cut Brkt

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Despite the invention of caged roller bearings around the late 1890's, and numerous patented ideas to utilise them to "improve" bottom brackets since, they had virtually evolved to a standstill. Almost all bicycles remained fitted with the traditional cup & cone type running on loose ball-bearings. By far the biggest improvement that was taken beyond the design stage to production came about, however, when London based cycle maker and engineer Maurice Selbach, replaced some traditional loose bearing assemblies, with enclosed bearing sets manufactured by the British Timken Co. The benefits were of reduced wear and maintenance as without the vagaries of setting up and keeping 'proper' adjustment, these bearing sets produce a free and easy running axle for long periods with little attention.

Many innovative designs to utilise plain and taper roller or ball bearings appeared in various guises in the years before 1949. The downside of these, however, was that almost all required a unique bracket shell to be made and used in combination with a specially made axle. In addition they could not be fitted retrospectively to the millions of bicycles already produced, and could not be adapted from those bottom brackets already commercially available from the established firms. Whether any of the larger cycle manufacturers ever gave much thought to the idea is not known. Though there were some clever designs patented or involving two of the leading bearing manufacturers, Timken and Skefco (SKF), it is clear that they did not become common fitment. Whilst the principles and benefits were universally accepted, few manufacturers adopted them, leaving that to some of the smaller names in the business.

When in 1949, Alex Singer applied for his brevet d'invention (patent), not only did he propose the use of annular bearings ² but he chose to do this through a process of conversion. This enabled it to be used on both new and old machines - in fact specific reference is made in the patent application, to its ability to be used with a bracket axle having worn cones. It could be applied equally to any of the bottom brackets already on the market. By conversion of the standard bracket shell, and purchase of an axle only, rather than a whole bracket set, it was a low cost improvement utilising commercially available annular bearing sets.

The patent application translates into an almost complete guide on carrying out the conversion, rather than the more usual 'framework' document.³ With the addition of accurate dimensions it was certainly not beyond the ability of most small machine shops or even home "constructeurs" to carry out this work.

The bottom bracket was first stripped down, and the original bearings and the cups discarded. The bracket axle was then machined to remove the fixed cones and reduced in diameter to provide a journal on both sides, for the annular bearing inner race.

The diameter of the middle section of the axle between the cones, also appears to have been reduced, to ensure that the inner spacer sat both against and partially under the bearing race. Two spacers were required, the first to match the thickness and diameter of the annular bearing outer race. The second and inner race spacer was, stepped down at the ends, split lengthways and sized marginally bigger to ensure that when installed it gripped the sides of the race. Spacer

Both spacers were of a length to ensure that the annular bearing sets were kept the correct distance apart, ran parallel to each other, and were properly located over the journals.

To accommodate the annular bearings in a true and correctly sized housing, the bracket shell was reamed out to fit the diameter of the outer race. Although this removed the existing threads, the shell was partially rethreaded on both sides for a short distance only, to accommodate the dust covers. These covers not only provided protection for the bearings but also positive location that, in combination with the two Dustcap

spacers, ensured, that the axle and bearings remained in proper alignment to each other and to the frame.

Reassembly was simply a matter of pressing one annular bearing set onto the axle, then installing the inner spacer by pressing it against and under the bearing inner race. The axle was then fitted to the bracket shell, followed by the outer spacer and the second annular bearing set. The bracket was completed by the fitment of the two dust-caps, effectively trapping the whole assembly. Modified Brkt

Aside from the obvious functional benefits of this conversion, in perhaps typical French style, there is something quite aesthetically appealing about the appearance of the flush disc covers on the converted bottom bracket. Most certainly better looking than the agricultural style bottom brackets that went before.

Almost two years after application, the patent was granted on 16 May 1951, and finally published on 4 September of the same year⁴.

¹. Drawing taken from CTC Gazette, did not credit this particular sketch to Daniel Rebour however other sketches used in the article were, and this is clearly his work.

². Annular bearing sets have a variety of names nowadays, the most common being 'single row deep groove bearings', where the balls run in grooved tracks between an inner and outer race assembled as a unit. This type of bearing is especially suitable for both radial (i.e. down & round) and axial (side to side) thrust loads. When provided with a suitable means of bearing retention, in this case from the dust covers, these bearing units provide a positive location of the bracket axle in relation to the bracket shell.

³. Most patent applications give only a "framework" of the invention designed to protect an idea. Generally the larger companies didn't want to give too much away to their competitors and in the case of small inventors, these were more often than not just "pipe dreams".

(a) French Ministry of Industry & Trade, Patent Application No. 989.098 Published September 4, 1951 (see below)

(b) The CTC Gazette Vol. 71 No.11 dated November 1952 Pages 825 & 829 : Report into the Paris Cycle Show of that year.

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