15 mph is a good bike speed

Speed ​​and comfort of a racing bike?

Guy Martin is obviously a decent cyclist, but you should note that his record-breaking ride took place in very special conditions. For starters, he built his own frame (or rather Jason Rourke built it for him). Next, he chose exactly where the run would take place - on sandy surfaces. And last but not least, it was towed to get up to top speed, which drastically reduced air resistance.

All of these things make his driving compare to the way you would drive, like comparing apples and oranges.

To get an idea of ​​the speed, you would probably get more of it by looking at professional road racers. These guys usually drive at speeds in excess of 25 miles per hour. Put them on special time trial bikes and they will reach a top speed of 50 km / h. And those are average speeds - you can imagine that gradient, wind and the ability to slipstream are factors plus or minus. Certainly the 70 km / h you mention isn't too much for her on the descent - I drove at more than that speed myself and lived to tell the story (I'm far from being a fast driver ).

But there are a few things you need to be aware of. First, these people are professional athletes, which immediately sets them apart from the rest of us. Their body is a little south of 5% fat, and you can see that the muscles they developed for cycling are disproportionately large. Second, the motorcycles the pros ride, an estimate of the cost of the ballpark would be maybe \$ 15,000 - which brings you a lot of ease. The typical weight of one of these motorcycles is probably no more than 6 or 7 kilograms.

Apply all of this to you. How good will the roads you drive be? Basically, the smoother the road, the faster you drive. If you had a racing bike how easy would it be? And there you are - how fast would your legs take you? These are all factors that will affect how fast you can go.

In response to your specific points, as I said, 60-70 km / h is not much in certain circumstances. I would imagine that most racing bikes could achieve this. The answer to where you would get them is pretty much everywhere. How often you could reach these speeds is up to you.

Your second point is stability. I would argue that stability is as much a factor of the bike as speed. For example, one of the big differences you would notice between a \$ 1,000 racing bike and a \$ 15,000 bike would be stability. A bike on the lower end should be fairly stable, but it has performance limitations. A high-end bike will perform better, but it will also require more skill in handling. I have observed that this is true regardless of speed - high-end motorcycles respond faster and are therefore "more nervous" (I am thinking of stability here as it is so easy to steer the bike). It's a bit like riding a donkey and riding a thoroughbred.