Sunday, March 27, 2011

The man who went up a hill and came down a mountain

Yesterday was the first real test of the P3 and my building skills. I went with some friends to Holmbury hill for a short ride. Well that was the aim, but they met someone who offered to show them some of the less popular trails. The result a rather longer day on the hill and a test of me and the bike.

I would love to say I spent the time flowing with the terrain and catching big air, but actually I spent frantic moments of concentration learning new routes and learning the ways of a new bike. Bits fell off, the result of not be quite tight enough, I didn't although my foot slipped from the pedals.  I also spent a lot of time letting my legs recover from the climbs.

First off it seems a torque wrench might be a worthwhile investment if you are building a bike that is going to be shaken by the ground. The handlebars slipped on a short downhill section, which was alarming. I also lost one of the front brake arms. It is possible that the brake boss problems are the cause or it may be the mechanic who put it together.

I also realise now that I need a few changes to improve the rideability of the bike. A 42 tooth front ring is not an ideal climbing ring for the average unfit weekend rider. It was hard work, perhaps made harder by trying to follow the lead riders up the hill in their granny rings when I needed to be going faster. I also can't push the crank round up in 9 for long enough. Perhaps one day I will be fit and trail wise enough to do this I don't think so either. The other problem was that other the hardening trails as the back kick out over stones and roots I would lose my connection with the big flat (cheap) pedals . A few shin bites resulted. I am now looking for a nice pair of clip in pedals with a wide foot bed.

Am I disappointed to have the bike now? No, it is fantastic to be riding something that I have worked on. The tinkering with all the little details is,  I guess, all part of the fun.

Sunday, March 20, 2011

Well it beats washing the car

Hooray - I have finally ridden the bike properly! I say properly because I have actually been on the bike round the park, but since that was as a means of keeping up with the kids while they cycled, I don;t really count it as a ride. Today was the first proper ride. Out along some local roads to a the nearest patch of dirt, mud and grass. Significantly it also has a small hillock on which you can pick up some reasonable speed over rough ground. Here at last then I can test some of the rideability of the bike and determine if there are any flaws in the build.

First impressions on riding out was that the bike was really comfortable. I had forgotten how much off the peg bikes are not designed round your length. So the distinct advantage of building from scratch was that I have been able to select component parts (mostly the headstem length) that factored in my body length. This also means my legs aren't cramping up under my arms, despite having a frame that is at the bottom of the size range for my height. There were two immediate issues that need some attention. The rear wheel isn't quite true, simple to fix. The gears have a habit of slipping, which isn't too serious and just needs some minor adjustment. Well at least I hope, but the worst case scenario is the shifter is more shot than it feels.

It felt odd to ride out with only 9 speed at your disposal, I kept reaching to change front rings and finding nothing on the handlebar. However, it really didn't dent my general speed over a rough, flat course. Very smooth would be my assessment of the overall ride, but I suspect it will glue itself to the ground on longer slopes. The front end did wash out in gravel on a twisty descent, but not seriously and no more than expected for a hardtail. I didn't push it downhill as there wasn't much and I had to be wary of other park users.

There is a pure joy in being able to do something and then look back and say I built that. I remember my uncle talking fondly in similar terms about a car and a motorbike he built from scratch. Its not the same sense of achievement of looking at a finished project and seeing others use it. Instead, because it is you using it there is a certain - connectedness.

Saturday, March 19, 2011

Evolution, revolution and mechanical assembly

When I started this blog I rather ambitiously likened myself as a bike builder to the blind watchmaker of Dawkin's fame. As if I can compete either with evolutionary forces or God, depending on what you believe! But then there are some serious points that can be considered from the whole process of building a bike and the creative process.

Initially, I think you need to decide if the process of life is creative or mechanical assembly. The bike building that I have just completed is essentially a mechanical assembly. You could argue that there was some creativity in determining the paint, and dealing with some of the potential problems. In reality though most of the choices were predetermined by the shape of the machine. However, in my mind whilst working there were creative processes working. I am thinking about frame geometry and sizes, wheel bases, tyres and the like. Now I am not a natural engineer and so this creative thinking is unlikely to result in a bike, but creative it is.

Think about all those bike designers who think about and have developed the geometry of the bicycle from the simple wooden horse, through the Penny farthing, and on to the modern bicycle forms we see today. Two hundred years of development and evolution. I find it all quite amazing that anyone would think of these changes to make a better machine. Then again perhaps necessity was the mother of invention. I can of course conceive that an individual would perhaps add a round "wheel" or find the addition of a pneumatic tyre beneficial. But you are left wondering how long things would take if it was left to a random stop/start process. The timescales are immense and the processes required to meet each stage complex. Understandable that we should seek a concept that describes what happens according to our own social understanding. The scientific method (often forgotten) is to formulate a hypothesis based on available evidence and to test hypothesis to destruction. So in reality all scientists are actually uncertain if any of the theories by which we build stuff and do things really works.

What about building a bike you say. Well I hardly did the work in a vacuum of knowledge. I have had a bike since I was 7 years old. So although perhaps not the most engineering of brains has managed to absorb one or two things in the intervening years. Then there are books, manufacturer's booklets and the Internet as a sources of information. Which, despite my best efforts I couldn't totally ignore. A good thing too, or I would still be trying to build the damn thing right now. My bank balance would be a lot emptier than it is now, and my shed would be full of components that did not fit. An excess of brake bosses is enough thank you very much. How long then for a blind bike builder to produce a modern bike from nothing?

Saturday, March 12, 2011

Time for reflection

I promised, sometime ago, that I would pause and reflect on my experiences of constructing a bike from scratch. I think I am going to split this into sections, mechanical, philosophy and riding.

On the mechanical side of things I am surprised. OK so this wasn't a design and build a bike from bits of steel, but I did start with nothing in mind. So it was a surprise that the mechanics of assembling a bike were quite simple. True I did have to buy some extra tools that were not in my basic bike tool box. This added to the overall cost of the build so perhaps not a good idea if you don't plan to build another, but I suggest that having built one you will build another.

What you do have to be careful of is mixing and matching components. Some gear shifters don't work with some mechs. Some bottom brackets don't fit some frames and also need different tools. Wheel hubs will only accept certain sizes of cassettes. Even the frames have different capacities that affect headsets and wheel/tyre choice. All in all the idea of just picking things up in a random fashion is not a good idea. From a mechanical stand point, I'd suggest a list of choices, and a little research. Being a blind bike builder can be a slow and expensive process.

Start off with an idea of what you are going to use the bike for and develop that. There are no rules that say what you initially put on the road/trail is the finished article, so don't hold out for the ultimate kit if you can get hold of an alternative that will get you out riding sooner. Parts will always need replacing, and I missed being able to ride when I had taken both bikes off the trail.

As you develop the idea of what you need the bike for, a certain frame type and gear/wheel combinations  follow on. Be guided by the price of components. Put the higher priced ones as the guide for getting the rest that are dependent on that.

Mechanical assembly is pretty straight forward. A bike is after all a bit of pre-fabricated engineering. Most bikes are developed to be relatively simple to assemble and parts in general fit a logical scheme. Whilst a generic understanding of how a bike fits together is important, either through analysis of an existing bike as a template or through experience, most of the build is suggested by location. Bolt front wheel to front axle, rear derailleur to rear stays on the right is not exactly rocket science.

Getting the tools for job is important, but a reasonable £30 bike mechanic kit will do all but fitting a headset and servicing the forks on a bike. As you can see from the blog the former needs some pretty specific tools, or which there are pro, amateur, and DIY versions. Depending on your choice of drive train you may also need a different tool for the bottom bracket. But if you stick to the taper type, you can save an awful lot of money if you are not requiring a high standard of performance.

Finally, what you don't know you can find out. I tried to do most of this build without to much reference to the internet and books, relying instead on my abilities to analyse a system and understand how it works. Having said that "Zinn and the art of mountain bike maintaince" was invaluable for checking my logic. If you get stuck and you need a practical demonstration then the Bicycle Tutor has excellent "how to " videos. Other riders were also helpful sources for ideas, although not always correct. You can find all sorts of conflicting advice on bike forums, based on conjecture and one off experience, they will give you an idea but don't take them as gospel. Instead, go to Sheldon Brown who has compiled lists of technical information in a much more rigourous manner.