To grease or not to grease a square taper bottom bracket axle?

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  • To grease or not to grease a square taper bottom bracket axle?
  • Premier Icon mttm
    Subscriber

    Not. In fact, degrease first.

    bencooper
    Member

    Yes, grease.

    Edit: this’ll be fun 😉

    No grease. Just because people do it doesn’t mean it’s correct. Think stabilisers.

    Premier Icon Yak
    Subscriber
    bencooper
    Member

    It’s one of those things where if you ask a bike mechanic he’ll probably say no. If you ask a proper engineer if you shouldn’t grease a taper fit, he’ll look at you as if you’re insane.

    orangeboy
    Member

    Shimano taper bb do often come with grease already on the axle
    But with middle burn arms I’d degrease them to keep things nice and creak free

    Don’t expect this thread to reach a firm conclusion

    bencooper
    Member

    Don’t expect this thread to reach a firm conclusion

    I’m expecting it to be a 5-pager with added insults by 2pm.

    jamiea
    Member

    Copper grease?

    Cheers,
    Jamie

    Premier Icon Yak
    Subscriber

    Isn’t about not forcing the crank too far onto the taper and knackering the crank?

    MadCowKev
    Member

    A question for retrobike surely?

    Premier Icon krixmeister
    Subscriber

    Loctite!

    Just joking. A very thin layer of grease, and ignore all naysayers.

    But as folks have said above – will be fun to watch this thread. Aw

    bencooper
    Member

    Isn’t about not forcing the crank too far onto the taper and knackering the crank?

    That is the theory. I’ve never seen it happen, and talking to quite a few people about it it seems to be an apocryphal rumour dating from the early Cyclotourist cranks which tended to snap everywhere.

    bencooper
    Member

    This is one of those subjects I file under “Cargo Cult Bike Mechanics” – along with things about the direction of pulling spokes on a wheel, using low speeds with a hole saw when mitering tubes, and always facing bottom bracket shells.

    Basically stuff that’s done because that’s how it’s always been done, not because anyone has actually thought about it.

    Premier Icon the-muffin-man
    Subscriber

    I’ve always put a dab of grease on and haven’t suffered any damage or cranks falling off.

    I have had trouble getting ungreased cranks off though.

    Premier Icon Yak
    Subscriber

    hmmm- might learn something here.
    [awaits some proper maths/fea/ nice graphs etc]

    Dibbs
    Member

    I spoke to Cliff at Royce about this once he said de-grease, I followed his instructions and never had a problem.

    Premier Icon leffeboy
    Subscriber

    I’ve always put a dab of grease on and haven’t suffered any damage or cranks falling off. I have had trouble getting ungreased cranks off though.

    Exactly as above. Had to cut a set of cranks off a bike recently so much prefer to grease. Might even try copper grease next time

    bencooper
    Member

    [awaits some proper maths/fea/ nice graphs etc]

    I did do some tests a long time ago – I’m now trying to remember where I filed it all 😉

    The conclusion, I think, was that with good cranks and a good BB, it didn’t matter in the slightest. With cheap cast cranks, greasing helped the crank bed onto the axle more consistently.

    Premier Icon Yak
    Subscriber

    bencooper – you could have ended the thread there! But cleverly your conclusion allows this to run on.

    Old deore hollowtech 1s – are they ‘cheap cast’ cranks?

    ktmblag
    Member
    lovewookie
    Member

    I tend to say no. based on regular (6-8 months) changes of BB’s or chainrings.

    however, this changes depending upon when you are.

    early 90’s, definite no. custom expensive lightweight cranks, cnc-ed to death + greased square taper often led to the crank travelling waay up the taper, either cracking the crank or just hitting the shoulder.

    early 00’s (or just before…), could probably do so. metal on metal contact needs some form of barrier really and materials and manufacturing was better, less prone to crank failures apart from cheap shyte.

    now…. probably not, if you’re running square taper you’re likely to have a budget set of cranks, which has a higher chance of being cheap soft shyte..maybe.

    it also depends on how and where you ride and how well you maintain your bike too, which is probably more critical.

    Premier Icon gary
    Subscriber

    Ah, flashbacks to rec.bicycles.tech circa 1990 🙂

    rec.bicycles FAQ : installing cranks

    (there is a ton of good info on those pages – I’d forgotten all about it!)

    GrumpyDave
    Member

    Same as the title really. Got some old Middleburns I’m thinking of fitting and I can’t remember wether the axle interface gets greased or not.

    Any help appreciated.
    Dave

    TuckerUK
    Member

    I grease, and always have (left school and went into mechanical engineering), Sheldon Brown greased, Jobst Brandt is also a greaser.

    Premier Icon Cheezpleez
    Subscriber

    Grease +1 – based on instinct, not science (but I’m convinced by the link above).

    mike_p
    Member

    I thought the rules were:

    Splines = grease
    No splines = no grease

    mickolas
    Member

    I coppaslip. If greasing is going to cause the crank to ‘slide'(ie stretch or crack) too far up the taper, then that crank richly deserves the death it finds IMO. I little lubrication to ensure peoper seating and reduce the chance of ‘settling’ looseness out on a ride. also had cranks bond themselves to bbs before. I imagine this wouldn’t be an issue for someone who changes BB or chainrings every 6 months or so.

    So maybe the question is: how long are the BB and crank going to stay together?

    clubber
    Member

    There’s no correct answer. I go with the following because it makes sense to me.

    – new cranks/bb – no grease because the mating surfaces should be flat and smooth and not need any lubrication to either reduce friction or prevent creaking

    – used – grease to reduce friction and the risk of creaking once there are marks on the surfaces.

    walleater
    Member

    bencooper – Member
    This is one of those subjects I file under “Cargo Cult Bike Mechanics” – along with things about the direction of pulling spokes on a wheel, using low speeds with a hole saw when mitering tubes, and always facing bottom bracket shells.

    Basically stuff that’s done because that’s how it’s always been done, not because anyone has actually thought about it.

    We have a winner!

    mickolas
    Member

    And coincidentally, my brother has the nickname “Grumpy Dave” on Tower FM in response to the texts he sends in to the morning show.

    Premier Icon epicyclo
    Subscriber

    In this climate I grease everything that I wish to remove later.

    In Oz I don’t need to.

    drofluf
    Member

    In the spirit compromise how about greasing the drive side and leaving the non-drive side ungreased? Surely that would make everybody happy….

    Premier Icon nedrapier
    Subscriber

    or alternating per face on the taper in the “loves me, loves me not” format?

    PJay
    Member

    I’m with Yak and Mike P on this one. I was under the impression that the advice was to grease Octalink/ISIS as there was a physical stop on the axle, but not to grease square taper as there was a risk of forcing the crank too far up the taper and cracking it (similarly, and for the same reason, I was under the impression that you shouldn’t just tighten up a lose square taper crank but pull it first then tighten to the correct torque).

    Premier Icon Clobber
    Subscriber

    If I don’t grease my (quality) cranks, they have all sorts of settling in problems.

    If I grease them, they are fit and forget (middleburn and white industries)

    Premier Icon Speshpaul
    Subscriber

    Copper slip, as its a alloy to steel or Ti inferface.

    Now move on nothing to see here 😀

    Sam
    Member

    risk of forcing the crank too far up the taper and cracking it (similarly, and for the same reason, I was under the impression that you shouldn’t just tighten up a lose square taper crank but pull it first then tighten to the correct torque).

    Read the piece by Jobst Brandt as linked above by Gary and he will explain both these things.

    Grease FTW.

    PeterPoddy
    Member

    Just so as you know, the correct way to do it, as they teach bike mechanics for Cytech 2, is NO GREASE.
    It’s not meant to move. It’s meant to stay still. So you don’t grease the taper.

    It is , however, acceptable to apply a drop of LIGHT oil which will ease assembly but be squeezed out as the taper settles in.

    Personally, I’ve NEVER EVER oiled or greased a taper and NEVER EVER had a problem fitting or removing cranks, probably because I know what I’m doing and have some decent tools though….. 😉

    Sam
    Member

    It’s not meant to move. It’s meant to stay still.

    So you never grease threads on assembly either? They are not meant to move.

    OCB
    Member

    Yeah, grease … but; and I dunno where I read the quote, but you only need as much grease as you’d “find on a mechanics finger” (this is clearly from a time before gloves / barrier creams) – which is to say, just a very thin moistening of grease on the faces.

    I’ve always done this and had no negative experiences, including over a couple of seasons of trials riding, which meant frequent BB swaps.

    In my experience, just that slither of grease has been fine – enough to facilitate straight-forward installation / extraction, and (but) nothing more.

    Possibly just as controversially – I do the same thing when installing headset cups too. 😛

Viewing 40 posts - 1 through 40 (of 65 total)

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