new bike purchase

sidedoor

i,m looking to purchase a giant defy advanced sl, now this bike will weigh 3kg less than my current dawes but it runs an 28 cassette, i use and need my 32' which my dawes runs so am concerned. how much will the weight diff compensate the extra wattage needed to turn the 28 up my fav hills. the real question is how much extra wattage does the 28 v 32 require?? both have the 34' crank i will add.also i will say i am 57yrs old 73 kgs fit as i can get at the moment. do roughly 150kms per week,so frightened by the saying you just gotta man up

dj58

I don't know the answer to the watts question, however if you think you need a 32T, can't you ask the bike shop to swop out the cassette and RD and you pay the difference in component costs? I've done this in the past, sometimes not being charged anything as the O.E. components are new and unused so can be sold as such by the bike shop.

Bobbinogs

You can play around with this site to your heart's content:

http://bikecalculator.com/

Ultimately though, only you will be able to tell what is acceptable and what isn't with gearing...after all, don't forget that you can put out the same power with a much smaller cog at the back...you just pedal slower! Climbing steep climbs is as much about being able to handle a slow bike at a low cadence as it is about pure grunt. Why not give the new bike a go, most would say that at only 73kg you should be able to get up most climbs on an unladen bike with 34/28. If you are struggling then swapping is a relatively easy option.