I already posted this about a week ago. Bought a new crankset (current one is Shimano Cues FC-U6000-1) and the spindle was too long. Sent it back because I was suspecting it was faulty and bought a Shimano DEORE FC-U51000-1 along with the correct BB-MT501. My BB Shell is 73mm wide. I would need a total of 5spacers between the BB and the shell to not have any play. At that point there is just too little thread engaged in the shell for me to trust this setup.
What am I doing wrong? I bought a crankset and BB that are supposed to be compatible with each other. The shell is supposed to be compatible with this setup. Why is there 10mm of play?
by NorbertTC
9 Comments
Did you confirm with calipers or a scale the width of your shell ?
https://preview.redd.it/efuh90slm4of1.jpeg?width=1125&format=pjpg&auto=webp&s=63b81407783373f1c8cf03117df143ed0aea7c34
I guess you mean fc-m5100-1 cranks – correct? If yes that seems really strange. Could you please post some pictures with a ruler so we can see what and where you did take your measurements?
Please also double check the width between you crank arms when they are assembled – should be around 96-97mm for the fc-m5100-1
A workaround for your current situation might be spacers that sit on the spindle of the crank…
Looked back through the previous post and you’ve ruled out an 83mm axle (there isn’t one in either of these cranks). You’ve confirmed your frame shell is definitely 73mm and you have the correct MTB BB (but it’s only a couple of mm difference anyway if you had a road one in there, not the 10mm you have).
How much axle is sticking out before you fit the LH arm? From memory, I think it should be around 16 or 18mm, certainly no more than 20mm. If this is correct then all I can think of is your LH arm isn’t fully on the axle.
You need to install the correct spacers on the bottom bracket. See the dealer manual: [https://si.shimano.com/en/dm/MAFC002/Bottom_Bracket](https://si.shimano.com/en/dm/MAFC002/Bottom_Bracket)
It seems like your non-drive side crank is not seated in properly, as the locking washer tab thing between the crank screws is not down in its hole.
Here is a pic of an XT FC-M8100 crank (52mm chainline) with an XT Hollowtech II BB-MT801 on my bike with a 68mm BB shell.
Note the spacers on the bottom bracket. Because I have a 135mm rear axle spacing, I used 2 spacers on the NDS and 1 on the drive side to get my CL as close to 48mm as possible.
https://preview.redd.it/7d6szglnt4of1.png?width=1080&format=png&auto=webp&s=73788e10eefebadd93ec9130d5848527781c99fd
Have you put your new crankset and your old crankset side by side to see how the spndle lengths compare? This seems like an abnormally large gap to fill with spacers. I’m assuming the non-driveside crank arm is install completely too? Did you tap it lightly with a rubber mallet to ensure the fit? Can you share a picture from the non-drive side of the crank and splindle interface?
you should only need one 2.5mm spacer when installing the bottom bracket for a 73mm shell *on the driveside*.
[EV-FC-M5100-1-4668.pdf](https://dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/ev/EV-FC-M5100-1-4668.pdf)
this diagram shows an install forfor a 68mm shell