ES25 Bottom bracket installation

larkim

My final post here on this subject (I hope).

http://techdocs.shimano.com/media/techd ... 657937.pdf

Attached shows instructions for installation. Says install the cartridge, and then the adaptor. Happy to follow that if that's what they say!

BUT...

Adaptor is plastic, and cartridge is metal. Given the high torque (relatively) for installing, and the logic that whichever end is tightened the "most" it will resist the tightening partly by the resistive action of the opposite screw, my natural inclination would have been to install the cartridge loosely, then the adaptor fairly tight (though to under the recommended torque), and finally tighten up on the cartridge side with the required level of torque, my logic being that if I tighten the plastic adaptor to 70N-m it might cause the adaptor to deform against the face of the frame slightly, whereas tightening from the other end would not cause such issues.

Am I overthinking things? (Entirely possible!)

Thanks!

Matt

arthur_scrimshaw

larkim wrote:

My final post here on this subject (I hope).

http://techdocs.shimano.com/media/techd ... 657937.pdf

Attached shows instructions for installation. Says install the cartridge, and then the adaptor. Happy to follow that if that's what they say!

BUT...

Adaptor is plastic, and cartridge is metal. Given the high torque (relatively) for installing, and the logic that whichever end is tightened the "most" it will resist the tightening partly by the resistive action of the opposite screw, my natural inclination would have been to install the cartridge loosely, then the adaptor fairly tight (though to under the recommended torque), and finally tighten up on the cartridge side with the required level of torque, my logic being that if I tighten the plastic adaptor to 70N-m it might cause the adaptor to deform against the face of the frame slightly, whereas tightening from the other end would not cause such issues.

Am I overthinking things? (Entirely possible!)

Thanks!

Matt

Yes

I've fitted loads, never had a problem, remember no lube on the plastic thread.

cooldad

I always assume Shimano have a vague idea of what they're talking about.
I also don't use a torque wrench, so that would just be a good 'forearm' tight.

.blitz

Have been down this road before with the same BB you will no doubt notice that although the adaptor is plastic the thread pitch is very fine and easily able to withstand the tightening torque. FWIW the next BB up in the range (ES51) has an aluminium adaptor which looks similarly fragile but isn't

larkim

Thanks one and all.

Interesting observation about not bothering with the torque wrench. Hell, I have one so I might as well use it!! To be honest, my usual limitation is my own strength (not a significant amount in truth), but you never know - I might turn into the Hulk whilst doing this tonight, so might as well give myself some protection against over-doing it!

As for Shimano knowing what they are on about, I agree - but I do think their nice pictoral diagrams leave ambiguities to the likes of me, particularly with my tendency towards over-thinking things. Always nice to know you can bounce thoughts off people who've actually done this in the past!

Thanks as ever!

The Rookie

The drive side needs installing fully home to ensure the correct chain line is achieved, how are you going to do that with the adaptor in the way? Shimano produce 100s of thousands of these so would guess they know more about it than you.

larkim

The Rookie wrote:

The drive side needs installing fully home to ensure the correct chain line is achieved, how are you going to do that with the adaptor in the way? Shimano produce 100s of thousands of these so would guess they know more about it than you.

I agree!!! But the drive side is the metal side (the RHS when sitting on the saddle), so at the back of my mind I was thinking "drive side must be flush for the chain line, doesn't matter if the non-drive side is ever-so-slightly proud."

The Rookie

Exactly, so screw the drive side in then but the non drive upto it, it does little laterally anyway and is more for radial support of the NDS bearing. You are now agreeing with Shimano and disagreeing with your first post so I'm now confused.

larkim

Having now completed it, I see your point. The metal end of the cartridge, even screwed in hand tight, seals flush with the frame (thus protecting the chain line), and I am left with the adaptor slightly proud (perhaps 0.5mm, if that), though it has been tightened with a torque wrench up to the max 70Nm. It all became much clearer when I was actually doing!

Thanks for the help and assistance - I know sometimes the response to a noob doing some of these jobs is "head down to the LBS, you'll avoid making costly mistakes", but if I don't try, I'll never learn! Without getting answers to some of the daft questions I've posted, I would have felt a little concerned that I was getting it right!

Bike is now silent in the BB area, so I can hear all of the other squeaks and groans!!

.blitz

larkim wrote:

left with the adaptor slightly proud (perhaps 0.5mm, if that)

Mine was similar but more so the wrong side of 1mm it wouldn't fit flush

The aluminium adaptor for the ES51 is 2-3 mm shorter and fits flush