Question

how friction helps and creates problem when we cycle

Answer 1

friction stops the bicycle from sliding.Thats how it helps while riding bicycle.....but the problem of friction while riding bicycle is that more effort is needed by us to oppose the friction while riding...in normal smooth surface much less effort is needed due to low friction

Answer 2

Friction is what helps you propel the bicycle forward - if not for friction between the bicycle's wheels and the pavement, the tires would just spin in place and the energy you put into pedalling would not translate into forward motion. 
friction can be bad if you fall off the bike - in this case the friction between your body and the pavement could scrape off your skin - ouch! 
on the other hand, without that friction, you would continue moving across the ground and not stop

hope this helps.......................