often wondered why …bit geekish I know but am i missing something?
In case you are confused by the question what I mean is that with some shimano bottom brackets the 2 retaining cups ( one being fixed to the cartridge itself) have different diameter internal splines and if you only have one size tool you’re stuffed. what’s the reason for this ? ….the spindle is the same width at both ends as is the bottom bracket shell.
anyone in the know?

Never noticed! Always used my one and only BB tool for removing Shimano & Raceface taperlock square taper BB’s and its always fitted. Could the splines be clogged with crud?

WTF are you on about?

erm…..

Not on mine they don’t (didn’t)

Sounds like you have a non-shimano plastic cup on one end.

something wrong there…

Sounds like you have one shimano and one something else – campag?

Or that that plastic cup on the non drive side has been wound in too far effectively making the tool part of the cup undersized!?

Or that that plastic cup on the non drive side has been wound in too far effectively making the tool part of the cup undersized!?

And WTF are you on about too?

Exactly what I said FFS!

Same tool fits both sides of all the Shimano BBs I’ve come across.
maybe the cup tool part of the splined interface section has wound too far into the centre sprocket, thereby rendering the spline section untooled?

I’ve actually seen it several times on shimano s tapers’s and have a bottom bracket tool with both sizes of spline ( one on each side )so it’s not a problem but just wanted to understand why it’s like that sometimes.Perhaps it’s only on the cheaper older bb’s like one i removed off an old gt avalanche tonight( plastic cup one end , steel fixed )

Kingtut…you seem to be the only one confused here ..WTF are you on?
For anyone interested I’ll dig it out and post a pic.

Er, I have five in my tool box (yes I know i’m a hoarder) and one on the bike, all but one have plastic cup one side and steel on the fixed side and I use the same tool both sides.

never seen a shimano square taper bb needing 2 tools (i have experienced twohats’ phenomenon tho)

i, also, dont understand what twohats means, the threads are the same diameter all the way rhrough a bb shell, they arent tapered.
if it gets tighter when screwed in then it needs a tread tap run through it to clean out the crap from the threads.
ive only ever seen one size of splined tool for shimano as well.

Ok,The plastic cup has a step on it’s outer edge that carries the splines, if you tighten it too much then the step can sometimes get drawn into the BB shell and compressed, this will inevitably cause the splines to tighten up on the tool,and give the impression that it requires a different tool.

only happens when you use the wrong cup-eg a 68mm in a 73mm shell…

mrs’ kona smoke has a cheap square taper bb with splines on drive side and oldskool notched ring thingy on the non drive side. But its not a shimano.

Ok I’ll be a bit more helpful in so far as to say I’ve never had to use two cup tools to fit a square taper (or octalink for that matter), so you have something very odd going on.

I fully agree why would they do that, luckily they don’t well least not what I’ve seen.

surely if you do it up too tight and the cup gets drawn in o the thread as Cynic_al claims then the tool would be unable to exit the cup when doing the job?? If it can come out it will go back in.

Heres a thought. 1 tool to fit different types of bb’s?

In the workshop I have fixed loads of bikes from expensive to utter crap and only ever found matching splints / same tool each side.
There is only one shimano bb tool available for square tapers
My guess is that one cup is arsed or it’s campy.

CruzHeckler not have a point…the tool will need wrestled out and won’t go back in by hand

aye,but it was the same fit as the unit itself before it was fitted.

Even clean adapter cups will grasp the tool from time to time once fully fitted. Its not going to make the fitting or removal impossible in the future,though.

here’s a bottom bracket tool i have (cyclus). both sides have 20 splines
but the outside diameters are slightly different as you can probably see.
on a number of bb’s over the years( as mentioned ) the larger size fitted the steel cup but was too big for the plastic cup which required the other side of the tool to be used. That is why I wondered why

Guess what. I fitted a durace hollowtech 1 bb this week and it had two different fittings
Regular shimano splined one side.
Odd notched fitting the other
Had to use a lockring tool (hooked type for fixies etc) to get it on.

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