Originally Posted by
atlantic90
ouch! I get it, though still not sure exactly why you used the "50-30" numbers. My front chainrings are 42 / 32 / 22. So wouldn't I use (42-22) + (36-11)? I know it still comes out to the same number but just curious. And just to be sure, the new cranks I want are 39 / 26 so: (39-26) + (36-11) =38. So I would be safe with my current RDER - correct?
I want to thank everyone who has respoonded - this has been both very helpful and informative. I have a few more questions, if anyone is still trudging through this thread
Can you guys give me some reccomendations on what type of BB will fit my bike AND those sram x7 cranks I linked in the 1st post?
Also, I'm mostly interested in durability / longevity for the bike so any reccomendations on a brand / model of BB would be appreciated. The budget would be ~$40.
Would I need any extra tools? I have standard garage tools bpus this set:
Nashbar Essential Tool Kit
Thanks again
I Guess I had the BB 30 in my mind, but you are correct that it's the same chain wrap.
Reducing your chain wrap by 2T will get in in the range of the RDER. Going to the 39-26 will give you a little extra margin to play with, without having to size your chain "EXACTLY" right. (consider that sometimes you are stuck with the odd 1/2-3/4" extra length because things just work out that way)
There have been 24-34-42T triples manufactured, but trying to find one WHEN you need it....