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Looking for some help
Got a disc road bike with 68mm bottom bracket spacing
A shimano 68/73 mtb bottom bracket
A rotor 3d xc3 crankset
I am struggling to get all this to fit together I seem too have too much or too little axle showing when I go to put the crank arm on
Any ideas?
road and mtb cranksets have different axle lengths even with the same BB spacing (which means I think that the bearing cups are different sized)
I think the cups for Shimano road and mtb bottom brackets are slightly different widths, with road being a mm or so thicker.
Thanks had a look at link but as I am using a MTB bottom bracket with the MTB crank it's appears it should all work but i can't seem to get it right
I am struggling to get all this to fit together I seem too have too much or too little axle showing when I go to put the crank arm on
So you are using spacers? Sounds like you need narrower ones.
If you are using MTB cups should be 1 spacer on one side and 2 on the other - nominally 2 on the drive side, but you can swap them to tweak the chainline. The overall BB width + spacers should measure 73mm though Shimano only seem to provide 2mm spacers these days but 74mm total width is OK.
Sell them and buy some road cranks. Why would you want a wider Q Factor when there is no need for one (I.e. to clear the wider chain stays of the MTB)
Why would you want a wider Q Factor
Because he doesn't want to buy cranks, and Q factor is a nonsense?