I have a road bike which has a Shimano 9-speed 12-25T cassette and a 105 rear deraillier and a road triple chain ring set. For touring this set-up is a little high strung on hills with gear in my panniers.

Could I change the cassette to a 9-speed Shimano Xt M760 cassette with 11-32T without chaninging anything but possibly chain length?

Any problems with doing this? I suspect the road 105 may not have a long enough arm.

I might instead just change my granny gear to something even smaller. I have a Truvativ Isoflow Road crank with 30:42:52. Is there a 25T for this crank?

Any suggestions? It's just for hill climbing with a load, as unloaded I don't use the granny 30 much at all.

Thanks.

Right, so-called "road" rear derailers generally won't go bigger than 30...but derailers are cheap! Suitable models start in the $20 range.

Yes, but odd sizes are very scarce, you'll pay a premium for them. For your crank they go down to 24.

See: https://harriscyclery.com/74 for information on this

Sheldon "Granny" Brown

Would a 26T be enough then? I do an occasional overnights and mostly club rides. Would a loss of 4 teeth be noticable?

Thanks for your help.

Going from a 30 tooth to a 26 tooth chainring would lower your gear by 13%. It would be the same as changing your largest cassette sprocket from a 25 to a 29, according to my trusty slide rule.

Would that be enough?

Gearing is a very personal matter, and it is difficult to give good specific recommendations for someone I haven't actually ridden with.

The best gearing for you depends on a large number of variables, including:

•Your weight
•Your strength
•Your endurance
•How far you'll be riding in a day
•How hard you're willing to push
•How much baggage you'll be carrying
•The steepness of the terrain
•The nature of the road surface

There is no magic formula for this, only experimentation will let you determine what gearing suits your needs.

You might find my online gear calculator useful for comparing with your present gearing:

https://sheldonbrown.com/gears

All the best,

Sheldon