[rockracing]

wow, borrowed a pair of middleburns and an action tec Ti BB from a mate with 29/42 rings, had such a great ride now, always felt in the right gear and really felt so fast, even considering going for a 2x9 ste up, I've got a 11-34t sram cassette, maybe on some really long climbs, the 29x34 might start to get a little tough and you don'y want to always be in such an extreme ratio.

just nice to try something different and enjoy it

anyone know of anyone else who makes a 2 ring crank ? Middleburn is Pricey !

 

[indieboy]

Originally posted by rockracing
wow, borrowed a pair of middleburns and an action tec Ti BB from a mate with 29/42 rings, had such a great ride now, always felt in the right gear and really felt so fast, even considering going for a 2x9 ste up, I've got a 11-34t sram cassette, maybe on some really long climbs, the 29x34 might start to get a little tough and you don'y want to always be in such an extreme ratio.

just nice to try something different and enjoy it

anyone know of anyone else who makes a 2 ring crank ? Middleburn is Pricey !

just drop the little ring on any crank and adjust your front mech....

 

[Mike B.]

Originally posted by rockracing

anyone know of anyone else who makes a 2 ring crank ? Middleburn is Pricey !

FRM makes a crank with just a 2 ring spider but indieboy is right. FRM isn't cheap either by the way but very light.

 

[SuspectDevice]

2 ring notes:
1. differences more than 10 teeth are unliked by shimano mtb deraileurs.

2. place a 2 mm spacer between the middle ring and the crankarm for less chain drop.

 

[rockracing]

Originally posted by SuspectDevice
2 ring notes:
1. differences more than 10 teeth are unliked by shimano mtb deraileurs.

funny that, when shimano cranks have a 12 tooth diff between the 44 and 32 blades ???

dropping the granny is fine but its the ring combo of 29 and 42 thats a bugger to find.

 

[punkassean]

Originally posted by rockracing
funny that, when shimano cranks have a 12 tooth diff between the 44 and 32 blades ???

dropping the granny is fine but its the ring combo of 29 and 42 thats a bugger to find.

you're right, it is supposed to be 12t but I have seen more run without problems. I run a 24-36 2x9 and it works great, but not for XC racing. What bolt circle are the middleburns? can't you use their rings on any cranks?

 

[rockracing]

Originally posted by punkassean
you're right, it is supposed to be 12t but I have seen more run without problems. I run a 24-36 2x9 and it works great, but not for XC racing. What bolt circle are the middleburns? can't you use their rings on any cranks?

middleburn's "duo" crankset rings are 3 fricken bolt design, works with nothing ! (except M-burn)

 

[oldfart]

All you need is a compact 5 bolt set up. I don't believe anyone makes a mid ring smaller than a 32 for the 4 bolt set ups, and 5 bolt standard drive will not take anything lower than a 32. I think you would also want a shorter bb and a road derailleur. Road cranks are typically 39 and 53 that's 14 tooth diff. And last year Tyler Hamilton rode a compact road set up for the alpine stages of the tour due to his broken collarbone. The standard 39 was not low enough. I think he used a FSA carbon crank with a 52 X 36 or maybe even a 34. Not sure but it has started a lot of riders trying this compact road thing and I don't think people are having too much shifting problems.

 

[rockracing]

Originally posted by oldfart
I think you would also want a shorter bb

yeah, it uses a 68 x 108mm