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I have a Giant contend 2 2017, its been a great work horse but now it needs changing, I got an Ultegra groupset for cheaper than a 2nd hand Ultegra spec bike. I've started with swapping the crank over, but noticed a gap between the BB and crank arm on non drive side that wasn't there on the claris crank. I'm assuming I need spacers but none came with Ultegra crank.

What measurements do I need to take to know:

  1. crank is in right position to too far one side or other.
  2. what size spacers if needed and fitted which side,

Tried looking for build manual but so many different variants can't find what I need.

Thanks

Matt

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  • Is it a double or triple chainset?
    – Noise
    Nov 17, 2020 at 22:51
  • Its a double chainset Nov 18, 2020 at 7:02
  • and what is the model number on the rhs/drive side crank please. Starts FC-
    – Noise
    Nov 18, 2020 at 8:27
  • On the off chance that it's an issue, did you install a Hollowtech II bottom bracket? Which model did you install? (FYI, the Contend 2 has an FSA Tempo crankset, and the current version on FSA's site is a square taper crank, so let's assume you removed the original BB.)
    – Weiwen Ng
    Nov 18, 2020 at 13:18
  • Hi its a bb500, the claris crank was an upgrade previous, it is spit of the ultegra just a bit heavier, I found the missing small spacer that locks up the crank it was still on the claris crank, thanks for the help Nov 18, 2020 at 23:14

1 Answer 1

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Some Hollowtech II cranks have a spacer that's supposed to go under the left crank. You need to find the exploded view diagram for your crank model to confirm this. Here's the one for FC-6703 for example, the triple crank for the second generation of Ultegra ten.

fc-6703

If you don't have it, it will probably be okay because these spacers don't interact with the seals in any particularly important way, although they do act as a sort of shield for the seal area to a limited extent. You do need something in its place though, or else you won't be able to preload the bearings. If this is the kind of seal you're missing, the simple thing to do would be get a bunch of scuff washers or whatever other tuneable stack of 24mm spindle spacers you can get your hands on. The nature of Hollowtech II is that as long as the spline engagement is complete give or take some very small amount, the exact dimension of the distance between the cranks doesn't really matter, so you're free in this case to just find something that takes up the gap.

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  • Hi I saw something like this but could not find one for the crank I have it is a double, as you said the crank arm is tight up against the splines so it can't go on any further, my only concern is without the right spacers the crank could be further "in" than it needs to be or as there is room the crank could drift back and forth changing its position with the front derailleur? Can't see anything apart from interference with the bearing cups that keep it in place? Nov 18, 2020 at 7:08
  • Yes, if your crank is one of the ones that a spacer like that, then without it there, the cranks will tons of free float. You need some kind of spacer there on such cranks. But, because of the nature of how these cranks adjust, the precise thickness of it doesn't matter. For example, the spacer in the above diagram says 3mm. If it got lost and replaced with a 3.1mm stack of scuff washers, that 0.1mm wouldn't be enough to throw anything off. Nov 18, 2020 at 7:37
  • Thanks for your help i found the spacer and it's all right now no float Nov 18, 2020 at 23:12

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