What makes a bike fast/good?

[aprilw]

Bare with me because I know next to nothing about bikes!

I have an MBK Super Sport road bike at Uni. I bought it randomly second hand because it was only £40, and it turns out its quite a good bike (correct me if I'm wrong - I really like riding it any way!)

Since its not practical to transport it back and forth between uni and my mum's house each christmas, easter and summer, I thought I'd buy another second hand bike to leave at home.

So again I purchased a random second hand bike for £40. I wasn't quite so lucky this time though... I guess I'm a bit spoiled, because this bike just feels rubbish in comparison with my lovely Mbk! Its much slower, both in terms of it's top speed and, most notably, the speed it accelerates at. When my MBK is in top gear I really feel the resistance when I'm setting off pedaling, and consequently I can really build up a good speed quite quickly, whereas this old raleigh seems to have hardly any resistance in top gear.

SO my question I suppose, is what makes a good bike, and most specifically, what makes a fast bike? Is it the make of the bike, the frame... gears, wheels... a combination??

Should I sell this Raleigh Esprit and just buy a better bike, or can I update and improve it?

If I am buying a new one, what key features should I keep my eye out for so I know if its any good?

If anyone can give me any advice, or tell me where I can get the answers to my questions, it'd be much appreciated.

Thankyou

[xerxes]

I'm not entirely sure what either of the bikes you mention look like, have you got any pictures? They need not necessarily be of your own bikes, but it would give us something to go on.

There are lots of factors that effect how a bike feels, tyres have quite a large effect, heavier, fatter, softer tyres with a more pronounced tread pattern will make a bike feel more sluggish than lighter, harder tyres with little or no tread. Frame geometry and stiffness, a more flexible frame with "lazier" angles won't feel as sharp as something stiffer with quicker steering. Then there's the overall weight of the bicycle, while a couple of pounds either way might not make a huge difference to performance, unless your racing, it can effect the way a bike feels, particularly when climbing or accelerating.

[nfmisso]

For me; stiffness and frame geometry are the top two characteristics.

Bike frame rigidity is stiffness. Does the frame deflect a noticeable amount when you are pedaling hard? It should not. Raleigh bikes generally have more than adequately stiff frames.

Frame geometry is how well does the bike fit you. Are the saddle, handle bars and crank properly located for the length of your arms and legs; and do the provide a comfortable riding position. Is the seat to crank distance large enough to get good leg extension. Most humans develop peak leg power when their legs are almost straight. Generally for maximum performance, you want roughly one third of your weight on the pedals, one third supported by your arms, and one third on the seat.

After frame stiffness and geometry; come tire pressure. The higher the tire pressure, the more lively and fast a bike will be. The difference between 60 psi and 90 psi can be two or more gears. That is, you will be able to comfortable maintain the same pedaling rate in two gears higher with tires inflated 90 psi versus tires inflated to 60 psi. Make sure not to exceed the pressure marked on the side wall of the tires.

whereas this old raleigh seems to have hardly any resistance in top gear
This is an indication that top gear on the Raleigh is too low for your riding conditions. I have a Raleigh Venture that I am in process of changing the largest chain ring from 44 teeth (44T) to 48T. This will increase the top gear ratio by almost 10%. In addition, I am changing the freewheel from one that has 14T in the smallest cog and 28T in the largest, to a 13-30T. 13 vs 14T is another 7½%. The 30T largest cog is so that my bottom gear changes very little (1.6 vs 1.57). The 13/48 gives me 3.69, where as the 14/44 is 3.38.

Both freewheels (or cassettes - there is a difference) and chain rings are relatively inexpensive, and easy to change.

[Joe_W]

Oh, and you should get your cadence up (RPMs when pedaling), much better for your knees...