Kebabs!!

Sorry, I always think of kebabs when I think about skewers. It is a perennial habit, that come summer and the BBQ season then most of our food will be cooked outdoors on a skewer. Late night drinkies, usually, result in a trip for a Shishkebab and chilli sauces. All of which is a diversion from the main topic of the post of fixing your wheels to your bike.

As I have mentioned previously, the wheels I picked up on ebay are missing a few bits. Mostly something to fit the wheel to the frame. Now I have a couple of quick release skewers knocking around in the shed from cheap wheels that have bent or broken rims. However, these are all front wheels. So thinking that a skewer, is a skewer is a skewer, I attempted to use one on the rear wheel which is missing any visible means of fixing. The skewer came up short. To check I took the one off the "new" front wheel and the same problem. The skewer does not go all the way through the axle. Reasoning this  through I worked out that it can't be a bolt on axle because that would be solid. So logic suggests that there must be such a thing as a rear axle QR skewer. A quick check and yes there is, but a huge array of different sizes. Time to do some research, I'm not rich so I can't afford to go buying different sizes and then selecting the one that fits.

Well this has lead me to think about Dollo's Law of Irreversibility - evolution tends to run in one direction. Having a bike hub with a quick release skewer means that it can never be held by a nut and of course vice versa. The designs are mutually exclusive. It is possible to "revert" to the more traditional nut based axle but in doing so I would need to make several changes to the hub that are not required for the axle but are for the process of conversion and allowing the wheel to work correctly. These changes are not impossible to complete, in this case bearings would need repacking, but things may never work as efficiently as they should.

Philosophically speaking then, why does evolution run like this. With bicycles as with much of engineering and design technology, it is about proprietory design, changes in materials, and cost effectiveness. I guess the surprising thing is that a similar set of imperitives exist in the evolutionary system. That is to say having something none of the others have, using a new resource and the energy cost required to effect the change. Does this mean that we can say both processes are effectively shaped by an underlying design principle?