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Discussion Starter · #1 ·
OK, this is my first build, but I've been riding and maintaining my bikes for over 15 years.

Just bought a Dolan CX frame and have a road bike with an FSA Gossimer compact crank and Ultegra everything else that I want to swap over. I picked up Avid 6 shorties and a English thread BB but when I put the cranks in and bolted it together the sprocket side crank arm hits the chainstay as it goes around. Can I space that out with washers and if so how much clearance should I have or do I need a special cx type crank? I was expecting everything to just go over to the new frame.

Thanks, this is probably the first of many questions, DK
 

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Sounds like you need a longer bottom bracket spindle - if such things exist for the type of bottom bracket you need (I'm not familiar with fsa cranks at all).
 

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Discussion Starter · #4 ·
Not sure what an IBIS bb is, but I just installed a new FSA bb that came with a green plastic cap that fits over the bb end and it says exodrive on it. Not sure what that is for (a spacer?), no instructions came with it and the bb screwed on without problem. A friend of mine brought over a new Gossimer crank he had and it looked like the same one I had but it fit, the crank arm missed the chainstay (just barely). On his is had a marking on it that said 130 BCD and mine said 110 BCD. It seems the span of the unit is the same, it's just the crank arms seem to have a little more bend to them allowing the clearance needed.

Still wondering if I just need to shim it out with a couple washers????

Thanks, DK
 

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daklugdad said:
Not sure what an IBIS bb is, but I just installed a new FSA bb that came with a green plastic cap that fits over the bb end and it says exodrive on it. Not sure what that is for (a spacer?), no instructions came with it and the bb screwed on without problem. A friend of mine brought over a new Gossimer crank he had and it looked like the same one I had but it fit, the crank arm missed the chainstay (just barely). On his is had a marking on it that said 130 BCD and mine said 110 BCD. It seems the span of the unit is the same, it's just the crank arms seem to have a little more bend to them allowing the clearance needed.

Still wondering if I just need to shim it out with a couple washers????

Thanks, DK
Ok, let's see: ISIS is an internal bearing design, where the spindle/axle is part of the BB. It sounds like you have an external bearing design (bearing cps are outside of the actual bb shell), which is a newer standard, where the bb has a hole through it for an axle to be inserted. The axle is attached to the back of the drive side crankarm.

Sounds like the arms on your crank are bent if you friend's similar unit has clearance.

130 and 110 bcd is the size of the chainring bolt diameter. This has nothing to do with the crankarms. It influences the size of chainrings you can use. Your 110 is what is referred to as "compact". 130 is a standard road double.

You can maybe try to shim it, but I'm not sure how safe that would be, as it would cause less threads to be engaged connecting the non-drive side arm to the spindle.

Another thing to check is the length of the spindle. You may have crankarms designed for singlespeed/fixed gear bikes, which typically have narrower BB shells. Measure yours and your friend's and compare.

I'd recommend you bring a trusted LBS into the folds and get some professional guidance. In my mind, replacing the crankarms is the safest bet
 

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krisdrum said:
Another thing to check is the length of the spindle. You may have crankarms designed for singlespeed/fixed gear bikes, which typically have narrower BB shells. Measure yours and your friend's and compare.
I don't think they design compact double cranksets for singlespeeds or fixed gears. :D

I'd check the BB. External BB cranksets tend to rely on the BB cups to adapt to different shell widths and chainlines. R'ing TFM, it seems like OP could have received an incompatible crankset/BB combination, in which case shims may not be an option.

The docs can be found here: http://road.fullspeedahead.com/fly.aspx?taxid=53&layout=product

Specifically, note the BB specs on page one of the installation manual

krisdrum said:
I'd recommend you bring a trusted LBS into the folds and get some professional guidance.
Best bet.
 

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Discussion Starter · #7 ·
I've got the Gossimer compact crank with 172.5 arms 10 speed double. The bike it's from is only about 2 years old (Iron Horse Victory) and never been crashed so I don't think the arms have been bent. My friend and I measured the spindle between the two and they were the same. I think some models have more of a curve in the arms than others and that's what I need to find, one with more curve. Looking at their website the pictures of the new cross cranksets, it looks like they might have that. Didn't know building bikes was this complicated. Wonder if the other Ultegra parts will fit now, levers, bottom and top derailleurs...
Thanks, DK
 

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daklugdad said:
I think some models have more of a curve in the arms than others and that's what I need to find, one with more curve. Looking at their website the pictures of the new cross cranksets, it looks like they might have that.
If your friend's crank was the triple version, the crank arm would sit further outward. The Q-factor (which measures this dimension) is the same for the compact and standard versions of the FSA Gossamer crank.
 
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