Almost everyone can ride a bicycle, yet apparently no one knows how they do it. I believe that the apparent simplicity and ease of the trick conceals much unrecognized subtlety, and I have spent some time and effort trying to discover the reasons for the bicycle's stability. Published theory on the topic is sketchy and presented mainly without experimental verification. In my investigations I hoped to identify the stabilizing features of normal bicycles by constructing abnormal ones lacking selected features (see figure 1). The failure of early unridable bicycles led me to a careful consideration of steering geometry, from which-with the aid of computer calculations-I designed and constructed an inherently unstable bicycle.

Ring-scission reactions of 1 -nitroso-Z-and 2-nitroso-1 -naphthol have been re-examined to obtain satisfactory routes to the o-cyanocinnamonitriles. New observations are made concerning these reactions and the different geometric stabilities of the various o-substituted cinnamic products. A coplanar anti-conformation for the o-substituted cis-cinnamonitriles is indicated by proton magnetic resonance results. In related experiments, ringopening of phthalidyl-acetic acid and -acetonitrile is effected with base under mild conditions to give, respectively, o-carboxy-trans-cinnamic acid and a mixture of o-carboxy-cis-and -trans-cinnamonitriles, from which the cisproduct is readily separated. The reason for these findings is discussed.

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Hydroxylamine adds under mild conditions to both nitrile groups of the o-cyanocinnamonitriles to give amidoximes whereas piperidine and ammonia add to the side-chain double bond to give p-amino-nitriles. Hydrazine adds at the P-position, and this is followed by cyclisation onto the o-substituent and substitution of reactive functional groups to yield 2-amino-3-cyanornethylisoindolin-1 -one hydrazone. A similar reaction is observed with o-carbamoyl-trans-cinnamamide in addition to the base-catalysed cyclisation to a 2-unsubstituted isoindolinone. Under more vigorous conditions o-cyano-cis-cinnamamide gives a phthalazine, evidently through dehydrogenation of the intermediate p-adduct.Light absorptions and l H n.m.r. results provide structural evidence. Amidoxime-l and -11 bands in the i.r. are recognised.