Does this look fitted correctly? Crankset.

[Willam]

Could someone please check this look fitted correctly, it's the first time I've fitted a whole new drivetrain. Just thinking the gaps between the cranks and the big are big?

 

[Yellow Saddle]

No.

 

[Yellow Saddle]

I assume that is a MTB with a 73mm wide bottom bracket.
If that is the case, then there should be one spacer on the right and none on the left.
If it is a 68mm BB, then there should be two spacers on the right and one on the left.

 

[Willam]

The spacers were as above then my lbs last replaced the bb, so I just did like wise...so should I swap the spacers around?

Trying to think what difference having 2 on the driveside v 2 on none driveside would make?

The chain line seems to be fine, completed the swap and the bike rode fine, the gears didn't even need adjusting.

 

[Yellow Saddle]

If you want to second-guess, don't ask for advice.

 

[Willam]

If you want to second-guess, don't ask for advice.

It's called learning mate, I like to know why, if that comes across as 'second guessing' then sorry about that, but it's the way I get to understand what I'm being told.

 

[lpretro1]

It's called learning mate, I like to know why, if that comes across as 'second guessing' then sorry about that, but it's the way I get to understand what I'm being told.

Don't worry William - you'll get used to the in-house self-styled oracles who sometimes make unpleasant/unnecessary comments - shame as often their advice is good - don't let i t put you off asking - we were all newbies once

 

[si_c]

Doesn't look quite right to me. Which bike do you have? And have you measured the width of the bottom bracket shell? That's the bit the cups screw into. Either 68 or 73mm.

 

[Willam]

Doesn't look quite right to me. Which bike do you have? And have you measured the width of the bottom bracket shell? That's the bit the cups screw into. Either 68 or 73mm.

It's a GT avalanche, the bb is 68mm.

 

[Willam]

Don't worry William - you'll get used to the in-house self-styled oracles who sometimes make unpleasant/unnecessary comments - shame as often their advice is good - don't let i t put you off asking - we were all newbies once

Cheers, I can see it can come across as a bit ungrateful, asking a question, getting an answer then asking why, but it's the only why I understand what I'm being told.

 

[Yellow Saddle]

Well, if you measured the width of the bottom bracket as requested, you would have had an even bigger answer.
Here's the full story.

Shimano Hollowtech II cranks come in one size and by size I mean the length of the crank's axle. You'll notice on the other hand that square taper and ISIS and Octalink BBs come in many sizes (lengths) to satisfy the various styles of frame out there.
Now, if you only make your crank in one size, then you have to do something to make it fit many frames. So you make it long and supply spacers to take up excess space.
Since there are two frame standards on screw-in BBs and two front derailer standards (one of which affects the effective BB length), you have to be clever.
The two frame standards are 68mm and 73mm. The difference in width is 5mm.
Further, the two broad types of FD available are ones that attach to the frame seat tube via clamp or braze-on. These don't affect the BB. However, there is another type of FD called E-type. This BB has a clamp that is held onto the bike via a bracket that sits between the BB cup and frame. Have a look at the E-type FD in the photo.

That black part is a plat that's 2.5mm wide.

Shimano thus supplies the Hollowtech BB with three spacers, each 2.5mm wide, but the crank is only supplied in one length which is the longest required for a 73mm BB and an E-type derailer.
The configuration is thus like this:
73mm BB with E-type FD - no spacers.
73mm with other (frame clamp type) FD - one spacer on the right (where the E-type FD would have been).
68mm with E-type - one spacer on the left and one on the right.
68mm without E-type - one spacer on the left and two on the right.

If you add up the 2.5mm spacings in each case - i.e. spacers or E-type bracket, you'll always get 75.5mm, which is the effective length of the axle on a Hollowtech crank.

Further, the location of the spacers are important so that the crank is in the middle of the bike.

In your case you have one spacer too many and your left crank's splines are thus not properly engaged and will strip out and the crank is not in the centre of the bike. Your chainline is still correct, because you have the right amount of spacers on the right, where it matters but your crank will strip, perhaps even the preload adjuster as well if you are not careful.

Edit: Thanks to the ever vigilant @Ajax Bay, my unofficial proof reader, I've corrected a mistake in the second option of the four possible configurations. I hope I had no-one scratching holes in their scalps whilst reading "without" when it should have been with. I've also added a clarifying bit in brackets.

 

[Willam]

Well, if you measured the width of the bottom bracket as requested, you would have had an even bigger answer.
Here's the full story.

Shimano Hollowtech II cranks come in one size and by size I mean the length of the crank's axle. You'll notice on the other hand that square taper and ISIS and Octalink BBs come in many sizes (lengths) to satisfy the various styles of frame out there.
Now, if you only make your crank in one size, then you have to do something to make it fit many frames. So you make it long and supply spacers to take up excess space.
Since there are two frame standards on screw-in BBs and two front derailer standards (one of which affects the effective BB length), you have to be clever.
The two frame standards are 68mm and 73mm. The difference in width is 5mm.
Further, the two broad types of FD available are ones that attach to the frame seat tube via clamp or braze-on. These don't affect the BB. However, there is another type of FD called E-type. This BB has a clamp that is held onto the bike via a bracket that sits between the BB cup and frame. Have a look at the E-type FD in the photo.
View attachment 148981

That black part is a plat that's 2.5mm wide.

Shimano thus supplies the Hollowtech BB with three spacers, each 2.5mm wide, but the crank is only supplied in one length which is the longest required for a 73mm BB and an E-type derailer.
The configuration is thus like this:
73mm BB with E-type FD - no spacers.
73mm with other (frame clamp type) FD - one spacer on the right (where the E-type FD would have been).
68mm with E-type - one spacer on the left and one on the right.
68mm without E-type - one spacer on the left and two on the right.

If you add up the 2.5mm spacings in each case - i.e. spacers or E-type bracket, you'll always get 75.5mm, which is the effective length of the axle on a Hollowtech crank.

Further, the location of the spacers are important so that the crank is in the middle of the bike.

In your case you have one spacer too many and your left crank's splines are thus not properly engaged and will strip out and the crank is not in the centre of the bike. Your chainline is still correct, because you have the right amount of spacers on the right, where it matters but your crank will strip, perhaps even the preload adjuster as well if you are not careful.

Edit: Thanks to the ever vigilant @Ajax Bay, my unofficial proof reader, I've corrected a mistake in the second option of the four possible configurations. I hope I had no-one scratching holes in their scalps whilst reading "without" when it should have been with. I've also added a clarifying bit in brackets.

Thank you appreciate that explanation.
I'll have to swap the spacers around then, maybe I was mistaken thinking they were fitted that way, but the bike shop could have got it wrong.

Just to add, when I removed the preload cap, I had to cut it away as it was stuck so maybe if the spacers were fitted incorrectly previously that might explain it.

 

[Ajax Bay]

the bike shop could have got it wrong

Not possible.

 

[Willam]

Thank you appreciate that explanation.
I'll have to swap the spacers around then, maybe I was mistaken thinking they were fitted that way, but the bike shop could have got it wrong.

Just to add, when I removed the preload cap, I had to cut it away as it was stuck so maybe if the spacers were fitted incorrectly previously that might explain it.

Thanks good them as the £60 they changed me to fit a new crankset/B&B and cassette would have seemed even more painful than it was.