Please help gearing advice

[vicmartinshowman]

Hi

I could do with some help.

I have a 9 speed cannondale double ( pride and Joy)

Can i do a straight swap of my 39t inner chainring and replace it with a 34t without any detrimental effect to my gearing. This would give me more help in the hills. this in effect give me a customised compact set.

Regards

[gary]

Hi Hope thid info helps
1) The cage of the front mech is too short, so that when it's as low as it will go whilst clearing the big chainring, when in small/small the chain drags across the bottom end of the cage.
Try fitting a smaller large chainring so you can drop the front mech a little lower on the seat tube, or just avoid using the small half of the cassette with the small chainring. If this doesn't appeal or or doesn't work, then a look at a new mech.

2) The curve of the outer plate of the front mech is sized for a 53 chainring. If the large chainring is too much smaller than this, the bottom end of the cage will be well away from the chainring. The result is that you get poorer shifting between the middle and small chainrings and back up onto the large chainring, especially under power. Generally 48 is OK, smaller is where the problems start.