The Whizzer engine became so popular that several manufacturers produced a bike intended for mounting the Whizzer engine kit. The 1947 Schwinn WZ507 bike (later designated S4) was a variation of the Schwinn cantilever frame patented in 1937.( The term "CANTILEVER" indicates that the frame has two lower top tubes, which run all the way from the head tube, cross the seat mast, and continue down to the rear drop-out.)The welds were heavier, and spokes were .105 inch diameter as opposed to the .080 inch standard gauge. The earliest ones (WZ) have the inside of the rear seat stays and chain stays pressed flat for belt clearance. On the later ones, the stays are dimpled, and there is a welded on brake arm anchor point, which is then connected to the brake arm by a strut. Seems the coaster brake sometimes tore through the standard bicycle type strap, and in some cases bent or cracked the frame, so a welded on anchor point was provided. Schwinn’s "knee action" spring fork was used. A Schwinn front brake was provided to assist the standard coaster brake. The coaster brakes are Bendix, New Departure, and Morrow.(I can personally attest that stopping the rear wheel with the coaster brake does not necessarily stop the bike, so all my bikes have front brakes.)

While a lot of collectors call 'em all "WZ", there are actually at least two different versions of the cantilever frame. Only the earliest were "WZ". The designation "WZ" and "S4" does not necessarily correspond to the change in design, but was done by Schwinn in the process of streamlining their numbering system.

(Thanks to Leon Dixon for straightening out the S4/WZ thing)

From 1947, Schwinn also had available a version of their DX frame intended for motorizing which was similarly modified.

Beginning in 1950, Whizzer produced a complete motor bike mounted on the Schwinn DX chassis(non- cantilever frame), see "Whizzer Special".

  In August of 1948 a smaller cantilever version, the 24 inch Schwinn S10 was offered. Both the S4 and S10 used the Schwinn S2 tubular rims. The S10 Schwinn with an "H" engine kit.

     Roadmaster also produced a Whizzer- purpose bike, the Roadmaster 226WH. It featured heavy spokes (.105 ga.) and a New Departure front brake. Whizzers association with Cleveland Welding actually pre- dates the association with Schwinn. The earliest "H" manuals illustrate Roadmaster bicycles, as does the earliest advertising.

    Huffman produced a bike which was intended for motorizing. Designated the Model 90SF, it featured .120 ga. spokes, a Morrow rear brake, and a New Departure front brake.

    All of the various manufacturers offered their products finished in Maroon and Cream. (Of Course!)

The Martin Company produced the "Roadrunner" chassis in several versions. Suitable for mounting the Whizzer or any of several other engines, it had no bicycle pedals, and so was started by pushing, or by means of a kick or pull starter. There are several small manual motorcycle transmissions of that era which have a kick- starter built in.

     In the Cantilever Frame, the two lower top tubes run all the way from the top of the down tube, pass the seat mast, and become the rear seat stays, which are welded to the drop out.

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