Chainset /cassette combination question

baz69

Can someone tell me best combination of gearing for hills ,mostly long drag hills I struggle on ,my average speed on flat is about 22 mph,my winter bike is 50/34 with 11/32 cassette,new bike has 50/34 with 12 /29 ,if I change chainset to 53/39 with 12/29 cassette what difference will this make ,

Nick Payne

If you're struggling on hills, then changing from 50/34 to 53/39 chainrings will make things worse. To get smaller gears you either need a) a cassette with a bigger large cog (means a new chain and probably new derailleur as well), or b) a smaller small chainring on the cranks (which probably means a new set of cranks). However, if you can comfortably maintain 22mph on flat ground, you shouldn't have a problem on long drags with either 34x29 or 34x32. 34x29 at a cadence of 80 equates to a bit over 7mph, and that should be easily maintainable even on a long 8-9% gradient.

baz69

Thanks for reply,I should have said that haven't got new bike yet but have choice of either 34/50 or 53/39 with the 12/29 cassette ,it's being build at moment with campy eps,winter bike using the 34/50 11/32 gearing fine on flats but want to make sure I have enough gearing to be comfortable on hills and on the short snappy climbs I can spin the legs without grinding,which on current set up works.

Nick Payne

If it was me, I'd put the same gearing on it as your present machine. As I would tell people for a hilly 200km Audax that I used to organise: "Put on a lower gear than you think you'll need. Better to have the low gear there and maybe not use it than to need it and not have it."

mercia_man

Nick is right. A 50/34 chainset with 12-29 cassette is what I use. Going for a 53/39 chainset with the same cassette will make hills much more difficult for you. If you ever do long rides in high mountains like the Alps, even a bottom gear of 34x29 might seem a bit high for comfort compared with your winter bike and its 32 big sprocket.

flasher

Smallest number on the front largest number on the back will give you the easiest gearing, however if you can maintain 22mph on the flat something is very wrong if you struggle on hills with 34/32 as that's just about the easiest standard combination gearing for hills, bigger than that you're into mountain bike range.

svetty

flasher wrote:

....however if you can maintain 22mph on the flat something is very wrong if you struggle on hills with 34/32 as that's just about the easiest standard combination gearing for hills, bigger than that you're into mountain bike range.

Agreed - anyone that can average 22 mph on the flat on his own is a pretty decent cyclist which makes his question a little puzzling. Unless he is an 18 stone powerhouse TT rider........

baz69

Thanks for answers,no iam not 18 st or powerhouse rider,11.5 st,but health probs ,only one lung ,which doesn't affect me on straights,just hills training myself to stabilise breathing but half way up a sharp but not very long hill I start struggling same on long drags ,legs ok just breathing ,am I correct in saying a 50/34 and a 53/39 with a 12/29 cassette will give more or less same ratios at bottom for climbing but the 53/39 means having to make less gear changes throughout to maintain speeds across range ,looked at a table of ratios and that I think seemed to be the conclusion.

mercia_man

No you are wrong. Having a 53/39 will have harder gears for climbing than 50/34 both with the same 12-29 cassette. Bottom gear with the 39 chainring would be virtually the same as second gear with the 34 chainring. So you would lose your bottom gear. This is exactly what you don't want if you need to make hill climbing easier.

baz69

Thanks Mercia man for valuable input,desicion made sticking to compact chainset.

mercia_man

Right decision, I reckon. Spinning smoothly with a low gear will get you up hills more easily and allow you to breathe better than having to grind up straining every muscle in a higher gear. As Nick Payne above said, there are always situations when any rider will wish for a lower gear.