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ISIS bottom bracket size for FSA Carbon Pro Cranks?(8 posts)

ISIS bottom bracket size for FSA Carbon Pro Cranks?annoyance
Sep 26, 2002 6:40 PM
I recently got a set of Full Speed Ahead Carbon Pro ISIS Cranks and there is no info on what length bottom bracket they require. I emailed FSA and searched all over but i can't find the info. i am guessing 113 though.

also, if anyone can recommend a good, light ISIS bb, let me know too.
Axel Lengh?5ive
Sep 27, 2002 5:19 PM
Are you referring to the axel length of the bottom bracket? If so, it has nothing to do with what kind of cranks you have. It has everything to do with what frame you have and finding out appropriate length for that bottom bracket shell. Consult the frame make or LBS.
^^^ what he said, and try FSA Ti BB extralightRaf1
Sep 27, 2002 8:56 PM
yes Axle Lengh!annoyance
Sep 29, 2002 9:08 AM
yes, i meant axle length. well now, i am using Shimano 600 cranks with a 109.5 axle length on a Aegis Aro Svelte. everything i have read in inverstigating this question indicates that is depends more on the cranks and the bend and angle of them than the bottom bracket cup length. perhaps that is wrong though.
Both right/wrong.grzy
Sep 30, 2002 2:28 PM
First you need to know the shell width of the BB on your frame, either 68 or 70 mm, typically 68 mm these days depending on the frame. Then you need to know the length of the BB spindle which has everything to do with the crank design and very little to do with the frame, unless you have some strange chainstay/crank arm interference, but that will ultimately throw off your chainline. Like I said you need to know the crank arm design to put the chainrings in the correct place. It's kind of amazing that the FSA people don't have the nominal values burned into their brains to make it easy for people to spend 2 or 3 times the amount of money on their product vs. something from Shimano that will be a no-brainer. Park makes a fairly good chainline tool, but it's only really useful for checking an existing configuration.
that is what i figured.annoyance
Sep 30, 2002 4:42 PM
i know the diameter is 68 mm, so that is not an issue. Just the axle length. FSA was no help. they finally answered and said this:

"In general, Bottom bracket length is much more determined by the frame than by the crank, so we can never give a definitive "this will work for every bike" answer to your question. In specific, we make many different variations of the Carbon Pro crank, and without more detailed info from you, I can't even guess what would work for your application."

which was of no help. i was quite amazed that they couldn't just tell me, it does not seem so difficult a question. i may just sell them at this point and get some Dura Ace, only 50 grams or so heavier anyway plus i already have a brand new DA BB. a pain!
thanks though!
that is what i figured.bobobo
Oct 1, 2002 6:24 PM
What youy really need to know in order to get the correct spindle length is to know what drivetrain setup you are going to run, Campy 10 speed, or shimano 9 speed. This knowledge (rear cassette, rear der) combined with the cranks you have bought will allow FSA to tell you what the correct spindle length is. It all has to do with proper chainline alignment, and unless you tell FSA what drivetrain you are planning on running your cranks with and which specific cranks you have they do not have a way of giving you an accurate answer although this info for different options should be listed on their website. To properly align your crank chainrings with record 10 cassette and rear der will require an different spinle length (probably 102 mm) versus running your FSA cranks with Shimano 9 speed cassette and rear der. BB axel length is determined by your frame, not the drivetrain.
This makes no sensegrzy
Oct 2, 2002 3:57 PM
So, assuming the guy knows if he's running Campy or Shimano, FSA can't tell him the correct spindle length for the cranks he already bought from them. Not in reality nor on their website. So after you go on to explain how BB axle length is determined the rear cassette you then contradict yourself and say it's really determined by the frame not the drivetrain.

F'ing beautiful man - do you even read or understand what you wrote? You gotta be stoned or something.