Replacing triple inner ring - sanity check

[roubaixtuesday]

I'm going to replace the inner 26 currently with a 24.

Before I get started, a quick stupid question: I do need to take the crankset off for this, right? It's many years since I've done this and want to make sure I'm not missing anything obvious.

Oh, and also, 24 is the smallest I can go to? It's a 5 arm square taper crankset.

Thanks in advance

 

[Sharky]

For the outer and middle rings, you don't have to take the cranks off, but as the inner is much smaller you won't be able to manipulate it off.
For the inner, what's the bcd?

 

[Blue Hills]

I think I'd take the cranks off anyway if they haven't been off in a while - helps to clean the cranks/chainrings/hidden bits of the frame.

and take the BB out if it's a catrtridge type and hasn't been out in a couple of years.

 

[roubaixtuesday]

For the inner, what's the bcd?

74

 

[Ming the Merciless]

Yes take it off.

 

[Sharky]

According to Sheldon brown, the smallest for a 74 is a 24

 

[Sharky]

If looking for a smaller gear, have you explored cassette sizes?

 

[roubaixtuesday]

If looking for a smaller gear, have you explored cassette sizes?

Yeah, it's a Sora 9 speed. Currently have 11-32 rear, and mech is good for 34 officially. I'm going to try an 11-36, likely ok and will fit an extender if need be. It's a tandem, gears are manageable unladen - recently tried out in the Alps- but we're hoping to do some more touring, so lower the better! 24/36 definitely a significant change from current 26/32 lowest gear, effectively two gears lower.

 

[Ming the Merciless]

According to Sheldon brown, the smallest for a 74 is a 24

I’d agree my xtr m970 crankset has an inner bcd of 64 and the inner chain ring is 22. This gives me a low gear of 22 x 34 on my recumbent.

 

[si_c]

Yeah, it's a Sora 9 speed. Currently have 11-32 rear, and mech is good for 34 officially. I'm going to try an 11-36, likely ok and will fit an extender if need be. It's a tandem, gears are manageable unladen - recently tried out in the Alps- but we're hoping to do some more touring, so lower the better! 24/36 definitely a significant change from current 26/32 lowest gear, effectively two gears lower.

I've had no problems fitting a 36t to an RD-R3000-GS rear derailleur, as you might expect it needs the b-tension screw winding in a bit, but it works fine. I matched it with a 52-36 crankset so fitting it with a 24t smallest sprocket should be fine.

 

[Ian H]

Or just add another ring.

 

[mickle]

Use a steel granny. A tandem will munch an alu one.

 

[ColinJ]

Use a steel granny. A tandem will munch an alu one.

I picked up a 26-tooth steel granny ring for a couple of pounds in a bike shop closing down sale. I have been using it for over 15 years and it still has plenty of life left in it!