I don't think you'd have to train much to get to 42k in 2 hours -- at least on a road bike. 20 kph is a pretty leisurely pace and even if you only train 3 days a week for a couple of months, I'm pretty sure you could do it.
100m in 9.6 seconds from a standing start, though... That would be pretty tough. You'd need a fixed gear bike, I think, and crazy grippy tyres :-) I've never ridden track and I often wonder what kind of acceleration those guys can get.
I agree the sprint will be pretty tough. Just a data point, the world record from Francois Pervis from a standing start for the 1k in cycling is 56.303 seconds, and his 250m split was 17.671 seconds during that record.
Assuming he reached his max speed at 100m and than held on to that speed until the finish, his 100m split was 10.0 seconds.
Obviously there are some questionable assumptions in there, but this is a world record holder on an event that is very close to an all out sprint, and these calculations suggest that he was slower than Bolt over the initial 100m.
I think a world class track cyclist could do it with a lower ratio on their gear than normal could do it, but a regular Joe most definitely couldn't.
The record for 100 m on foot and 200 m on bike (on track) are roughly the same, just under 10 seconds. The latter is with flying start though.
As for the 10s from standing still, it shouldn't be that hard. I think I could do it, and while I do use my bikes somewhat often, I'm by no means an "athlete". Anyway, having a fixed gear wouldn't play any role in it, nor would have the grippiness of tyres (they are all grippy enough).
Just to note, I wasn't even thinking about the standing start part! (I appreciate people's calculations on that point.) Even ignoring the standing start, the fastest speed I seem to be able to reach on my bike on level ground is about 35-40 kph, which is about as fast as Usain Bolt runs in sprint events.
But the acceleration issue is clearly also very significant and I hadn't put much thought into it.
It's still faster than current my long-distance pace. What people tell me I'm missing is that I've never adopted clipless pedals (pedal cleats) and am still riding flat pedals even over 100 km and 100 mi distances. So I'm not getting power on the upstroke as 95% of the other event participants probably are.
That's quite surprising. For 100 mi (160 km), that means you are in the saddle for more than 8 hours! That's pretty impressive in itself. I helped my wife train up from nothing (not having ridden a bike in 20 years) to a 90 km ride in 4 hours. Admittedly we were riding 5 days a week, but it only took 3 months. One thing you might try (if you are keen) is riding shorter distances at higher intensity (say 25 km in 1 hour).
As for clipless pedals, I'll agree with the other poster who says that they have limited value for power. Their main use (IMHO) is safety. Never again have your foot slip off the pedals when it is raining. Never again have to concentrate on your feet when you are riding over uneven surfaces. I've spent a fair amount on my bike and nothing has come close to the value of clipless pedals in terms of increasing the enjoyment of my ride.
100m in 9.6 seconds from a standing start, though... That would be pretty tough. You'd need a fixed gear bike, I think, and crazy grippy tyres :-) I've never ridden track and I often wonder what kind of acceleration those guys can get.