You will get the hang of what you need, bike-wise, by looking around and comparing. Feel some bikes, pick them up, sit on as many as you can, do some test rides, and, if you are lucky, buy one that fits you. Then ride it and get that immediate urge to change a few things. For which my advice is, don’t be rash. If you haven’t had a lot of experience on a lightweight high performance bike before it will feel odd. Flighty. Maybe uncomfortable. Too quick in the steering. Too…uncompromising? Just strange. You may not think so after a few hundred kilometres in the saddle, however.
I won’t attempt to give you bike set-up advice beyond my own experience, so here are some measurements that have worked for me - and probably won't work so well for you.
I’m about 169cm tall, and for riders around that height I’d suggest frame sizes between 53 and 55cm (ie pretty small but not the smallest!). Remember, smaller frames are lighter and stiffer, but if too small will compromise balance and comfort. And you will risk damage to components as well as yourself!
Handlebars, for frames between 51 and 55cm should be about 38 or 39cm wide, but shouldn’t cramp you or spread your arms too widely. Shoulders vary in width, but generally speaking arms should comfortably fall onto the drops without any serious effort. You shouldn’t feel ‘splayed’ when you tuck down into the drops of the handlebars.
Your own dimensions are vital, but I lean towards stem extensions of about 9 or 10cm. You used to be able to buy goosenecks that allowed variation, and some modern examples exist, but are less common. Stem length alters your weight distribution more than you'd imagine - a long stem puts you further forward and you'll get a decided feeling of flopping around when out of the saddle. Be warned, it can feel off-putting!
Cranks are usually about 170cm, however you may prefer the leverage of a longer crank, especially for road racing or timetrialling. Riders taller than myself tend towards longer cranks, and lengths from 172.5 up to 180cm are options; but you will find that you lose the suppleness of your spin and may tend towards grovelling in a big gear. Nothing worse, really.
Shorter cranks are suited to track bikes and criteriums, where touching a pedal on the banking or in a corner is not a good idea. I was once racing on a street circuit where we were sharing the road with the local Sunday morning traffic. I broke away from the bunch up a short, short rise and put a bit of distance into them. So when I arrived at the next left-turn I was alone, without the benefit of a big, highly visible bunch. Ahead of me was a car about to turn right across my path.
Many times have I been in this situation – will that car give way, or won’t it? Well, it did, but not before I was distracted enough to turn into the corner a bit late, sharpening the bend. I was riding my road bike, a Colnago, rather than my regular criterium bike and I completely forgot about the longer cranks and lower bottom bracket.
In an instant, at bottom dead centre of the left-hand crank rotation, my pedal struck the road and levered my rear wheel into the air. The bike went up and sideways in one motion, before settling. I didn’t come off but I lost time getting my balance back and found myself heading for the median strip. Rather than turn harder to the left and try to miss it, I went over it, or tried to, anyway.
When I landed I was flat on my back, the bike was up the road and I had (luckily) somersaulted a post and a small bush, to end up facing from whence I had come. The bike was in one piece, just a few scratches and nothing broken. No damage to the rider, just stunned embarrassment
Labels: angles, bike racing, bikeracing 101, bikes, frames