There is an interesting Q&A on independent.co.uk (though it dates from 1995) talking about bananas and tennis...
Q. Witnessing players at Wimbledon
chomping their way through pounds of
bananas between games prompts the
question: who began this sporting food
fad and are there sound nutritional
reasons for the players' preference
for bananas to other fruit or food. In
what other sports (leaving aside lunch
and tea breaks in cricket) do the
participants eat during the course of
play?
A. The sporting fad for bananas was
started by sports nutritionists such
as myself. The banana is rich in
carbohydrate - an important source of
energy for athletes and has
significantly higher levels than any
other fruit. Also, unlike most other
forms of high-carbohydrate foods, it
contains very little fat but is also
high in fibre. The combination of
fibre with the banana's three natural
sugars - fructose, sucrose and glucose
- means it provides a sustained boost to flagging energy levels, thus so
many players at Wimbledon were seen
eating bananas.
Bananas are also an excellent recovery
food for replacing potassium lost in
sweating, something most players must
have been suffering from at this
year's tournament. - Jane Griffin,
Consultant Nutritionist to the British
Olympic Association, London SW17
Sounds like it would be good for long bike rides as well.