Why does my XTR crank loosen up aftereach ride.

Hi 1 year old xtr crank on xtr splined bb.

After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie - when
I tighten the bolt all the way, the 8m allen key is in the 12'oclock position, after the ride, the
same key is in the 9'oclock position.

Is it the bolt that is coming loose or the crank? what could cause this? componant wear? grease (I
have some copperslip / antisieze between the bolt and the BB thread and between the crank splines
and the bb splines (not much but a little).

Should I try something like locktight to keep things snug for longer? new crank bolts? or do you
think things are wearing out?

I know thats a lot of questions, but I wanted to get all the possibilities (other than I'm
jinx'd) in...

cheers,

 

Not meaning to make you sound stupid, but are you sure you've torqued the bolts tight enough?

I've never worked with the splined BB's Partly because, IMO, they're just another attempt by Shimano
to be different (read: incompatible).

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

 

anonymous writes shyly:

> Hi 1 year old XTR crank on XTR splined BB.

> After each ride (say an hour and a half) the crank bolt looses up by about a quarter turn. ie -
> when I tighten the bolt all the way, the 8mm allen key is in the 12 o'clock position, after the
> ride, it is in the 9 o'clock position.

I think you have the problem that I foresaw when these spline fit cranks were first introduced. At
the time I hadn't realized that Shimano relied on that most riders lead with the left foot. That is
when coasting, standing on the pedals, they ride with the left foot forward. Retaining bolt
loosening can occur only with weight on both pedals, right foot forward, because this is the only
condition under which the spindle transmits reverse torque... to take up elastic and real backlash
in the splines. These splines have no press fit and do not fit snugly, so they have backlash on the
outset, plus backlash incurred by elasticity in the spline teeth.

I would like to know whether you are a right foot forward rider. We have heard from others with this
problem and they were right foot forward as I am. That's why I don't have these cranks. Shimano
apparently knows about this and come up with another idea in their latest cranks that do not use
this system as we see in:

http://tinyurl.com/cdxe

Jobst Brandt [email protected] Palo Alto CA

 

no-<< Hi 1 year old xtr crank on xtr splined bb.

After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie

make sure the bolt is tight, that is, tighten it with a long 8mm allen until it stops....

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

"Me" <[email protected]> wrote in message news:<[email protected]>...
> Hi 1 year old xtr crank on xtr splined bb.
>
> After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie -
> when I tighten the bolt all the way, the 8m allen key is in the 12'oclock position, after the
> ride, the same key is in the 9'oclock position.
>

is the bolt actually turning, or are you just able to re-tighten the bolt after every ride? if it is
the former, than i would say that you are not tightening your bolts enough, and they are vibrating
loose. check this by marking on the metal bit with a permanent marker, remembering where the mark is
in relation to the crank arm, and checking before and after a ride.

if it is the latter- ie: your bolt always seems to need re-tightening after a ride- then do this:

Stop Tightening It.

you are supposed to really crank those bolts down first time you put them on. after that, ive heard
a second retightening after a while doesnt hurt. but becuase of the way the crank is attached to the
spindle, i believe the metal deforms just a wee bit, and although it is still firmyl on there, the
*bolt* will be looser than you left it. just leave it like that. if you keep re-tightening it, you
can split the crank arm over the spindle. or so i've heard.

check the archives in the long threads about greasing spindle tapers for stories about people who
retighten their crank bolts again and again and eventually split them.

> Is it the bolt that is coming loose or the crank? what could cause this? componant wear? grease (I
> have some copperslip / antisieze between the bolt and the BB thread and between the crank splines
> and the bb splines (not much but a little).
>

that grease shouldnt do anything bad.

> Should I try something like locktight to keep things snug for longer? new crank bolts? or do you
> think things are wearing out?

if you need locktight, id venture to guess that things need some higher form of help. tightening to
spec should do the trick.

cheers, anthony

 

"Me" <[email protected]> wrote in message news:<[email protected]>...
> Hi 1 year old xtr crank on xtr splined bb.
>
> After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie -
> when I tighten the bolt all the way, the 8m allen key is in the 12'oclock position, after the
> ride, the same key is in the 9'oclock position.
>
>
You may want to check the specified torque required for
the crank bolts. I finally spent the money for an allen-key
socket(?term) for my $10 torque wrench, and discovered that
I'd been way below the required torque for a conventional
crank, even using a 5" extender on a regular 8mm allen key.

I recall seeing lengthy discussions about installing regular cranks, I'm pretty sure the splined
ones have also been discussed.

You might search www.deja.com, or see if www.sheldonbrown.com or the faq have anything.

hth

 

Hi, I'm the origional poster.

Yeah, I guess I should buy a torque spanner before I complain about the things loosing on me.

I'll have to mark the crank bolt as well as one of the previous posters pointed out I dont know if
its the bolt that is moving or if its just needs retightening.

Its myguess however that I am tightening it enough. I have two other road splines (one ultegra and
one dura ace) and seem to do them alright. But then again, perhaps I've overtightend them at one
point and have deformed something.

Jobst, I am definately a right forward pedal rider so I guess I work into yor theory.

If I get a toque wrench, what range rating should I get? I know some are for measuring large amounts
of torque and some for smaller.

please advise, and thanks to everyone for the advice....

"mark freedman" <[email protected]> wrote in message
news:[email protected]...
> "Me" <[email protected]> wrote in message
news:<[email protected]>...
> > Hi 1 year old xtr crank on xtr splined bb.
> >
> > After each ride (say an hour and a half) the crankbolt looses up by
about a
> > quarter turn. ie - when I tighten the bolt all the way, the 8m allen key
is
> > in the 12'oclock position, after the ride, the same key is in the
9'oclock
> > position.
> >
> >
> You may want to check the specified torque required for
> the crank bolts. I finally spent the money for an allen-key
> socket(?term) for my $10 torque wrench, and discovered that
> I'd been way below the required torque for a conventional
> crank, even using a 5" extender on a regular 8mm allen key.
>
> I recall seeing lengthy discussions about installing regular cranks, I'm pretty sure the
> splined ones have also been discussed.
>
> You might search www.deja.com, or see if www.sheldonbrown.com or the faq have anything.
>
> hth

 

Mark Freedman writes:

>> After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie -
>> when I tighten the bolt all the way, the 8m allen key is in the 12 o'clockw position, after the
>> ride, the same key is in the 9 o'clock position.

> You may want to check the specified torque required for the crank bolts. I finally spent the money
> for an allen-key socket(?term) for my $10 torque wrench, and discovered that I'd been way below
> the required torque for a conventional crank, even using a 5" extender on a regular 8mm allen key.

> I recall seeing lengthy discussions about installing regular cranks, I'm pretty sure the splined
> ones have also been discussed.

That is one of the main reasons for using a spline drive, to avoid dependence on a specific high
installation torque. This attachment is not sensitive to retaining bolt tightness. The crank
bottoms against a shoulder and can go no farther. Therefore, installation tightness of the
retaining screw need be only tight enough that it does not rattle loose. There is a different
mechanism at work here.

I am fairly certain the problem is right foot forward standing. I predicted this when these cranks
were introduced and was surprised to learn how few people stand on their pedals that way. All the
complaints of loose cranks in this news group were right foot forward riders.

Jobst Brandt [email protected] Palo Alto CA

 

anonymous replies secretively:

> Hi, I'm the origional poster.

> Yeah, I guess I should buy a torque spanner before I complain about the things loosing on me.

No you shouldn't. It will have no effect on the loosening.

> I'll have to mark the crank bolt as well as one of the previous posters pointed out I don't know
> if its the bolt that is moving or if its just needs re-tightening.

This is not a press fit taper crank attachment and is not sensitive to tightening. By all means
grease the interface whether it's a spline drive or a tapered square... or and ISIS for that matter.

> Its my guess however that I am tightening it enough. I have two other road splines (one Ultegra
> and one DuraAce) and seem to do them alright. But then again, perhaps I've overtightened them at
> one point and have deformed something.

You're grasping at straws. You need to change your riding technique or get different cranks.

> Jobst, I am definately a right forward pedal rider so I guess I work into your theory.

It's more than a theory. Believe it!

> If I get a toque wrench, what range rating should I get? I know some are for measuring large
> amounts of torque and some for smaller.

> please advise, and thanks to everyone for the advice....

Who are you? Do you work for the CIA?

Jobst Brandt [email protected] Palo Alto CA

 

<[email protected]> wrote in message news:[email protected]...
>These splines have no press fit and do not fit snugly, so they have backlash on the outset, plus
>backlash incurred by elasticity in the spline teeth.

FWIW, I actually measured some Shimano Ultegra parts some time ago and observed the following:

BB spindle spline width dimensions (average of 8 measurements at each specified location):

inner: 2.22 mm mid spline: 2.15 mm tip of spline: 2.10 mm

Crank gap width (female feature in crank) - 1.80 mm

1) the aluminum female crank feature is undersized by ~ 0.3 mm - material was removed on
installation - it was unavoidable.

2) there is a taper within the face of the spindle spline (FWIW on a separate Shimano spindle that
was produced 3 years prior to this one, I measured the same dimensions - albeit on only one
spline feature at the time)

For a picture of one of the parts I measured check out:

http://tinyurl.com/cl7g

I have also failed the spline on this style of crank previously:

http://tinyurl.com/cl89

and would consider myself a left foot forward person - though, the right does go forward on occasion
(as is bound to happen with anyone).

--
==================
Kraig Willett www.biketechreview.com
==================

 

Libenter homines id quod volunt credunt.

On Sat, 24 May 2003 03:08:42 GMT, [email protected] wrote:

>I think you have the problem that I foresaw when these spline fit cranks were first introduced.
><SNIP> These splines have no press fit and do not fit snugly, so they have backlash on the outset,
>plus backlash incurred by elasticity in the spline teeth.

If you would revisit this matter, I believe you'd find a meaningful difference between early
production Shimano splined cranks and those produced in subsequent years. Although I have seen no
"official" change in the maker's specifications, my anecdotal experience has been that cranks
produced in the past few years fit much more snugly on their crankbearing spindles, effectively
mimicking a press fit. In initial installation, new ones feel markedly different than the earliest
of these cranks whose fastening bolts would readily bottom out before reaching high torque values as
you repeatedly point out here and elsewhere.

-------------------------------
http://www.businesscycles.com John Dacey Business Cycles, Miami, Florida 305-273-4440 Now in our
twentieth year. Our catalog of track equipment: seventh year online
-------------------------------

 

[email protected] writes:

> I am fairly certain the problem is right foot forward standing. I predicted this when these cranks
> were introduced and was surprised to learn how few people stand on their pedals that way. All the
> complaints of loose cranks in this news group were right foot forward riders.

Right foot forward corresponds to being "goofy footed," a skate boarding/surfing and now
snowboarding term. People who "board" right foot forward, including myself, are definitely in the
minority. On the bike I prefer the right foot forward.

Joe

 

[email protected] (ant) wrote in message

> blah blah blah

sorry. im not up to date on my components, and thoguht this was a tapered crank. disregard my post
(as if i had to tell you, but anyway..)

cheers

 

[email protected] wrote:
> anonymous writes shyly:
>
>
>>Hi 1 year old XTR crank on XTR splined BB.
>
>
>>After each ride (say an hour and a half) the crank bolt looses up by about a quarter turn. ie -
>>when I tighten the bolt all the way, the 8mm allen key is in the 12 o'clock position, after the
>>ride, it is in the 9 o'clock position.
>
>
> I think you have the problem that I foresaw when these spline fit cranks were first introduced. At
> the time I hadn't realized that Shimano relied on that most riders lead with the left foot. That
> is when coasting, standing on the pedals, they ride with the left foot forward. Retaining bolt
> loosening can occur only with weight on both pedals, right foot forward, because this is the only
> condition under which the spindle transmits reverse torque... to take up elastic and real backlash
> in the splines. These splines have no press fit and do not fit snugly, so they have backlash on
> the outset, plus backlash incurred by elasticity in the spline teeth.
>
> I would like to know whether you are a right foot forward rider. We have heard from others with
> this problem and they were right foot forward as I am. That's why I don't have these cranks.
> Shimano apparently knows about this and come up with another idea in their latest cranks that do
> not use this system as we see in:
>
> http://tinyurl.com/cdxe
>
> Jobst Brandt [email protected] Palo Alto CA

I ride right foot forward and had this problem -- I was told that it was that I was heavy and
the cranks were made of too soft an alloy for me. It's why I switched to ISIS -- and have never
had a problem.

David

 

Qui si parla Campagnolo wrote:
> no-<< Hi 1 year old xtr crank on xtr splined bb.
>
> After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie
>
> make sure the bolt is tight, that is, tighten it with a long 8mm allen until it stops....
>
> Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
> (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

IME, that's not enough. I use a torque wrench to get to 35 ft-lbs. Over time, even that wasn't
enough so I switched to ISIS and haven't had a problem since (except that first couple of
tightenings that took 60 ft-lbs to seat the cranks!!!).

David

 

ant wrote:
> "Me" <[email protected]> wrote in message news:<[email protected]>...
>
>>Hi 1 year old xtr crank on xtr splined bb.
>>
>>After each ride (say an hour and a half) the crankbolt looses up by about a quarter turn. ie -
>>when I tighten the bolt all the way, the 8m allen key is in the 12'oclock position, after the
>>ride, the same key is in the 9'oclock position.
>>
>
>
> is the bolt actually turning, or are you just able to re-tighten the bolt after every ride? if it
> is the former, than i would say that you are not tightening your bolts enough, and they are
> vibrating loose. check this by marking on the metal bit with a permanent marker, remembering where
> the mark is in relation to the crank arm, and checking before and after a ride.
>
> if it is the latter- ie: your bolt always seems to need re-tightening after a ride- then do this:
>
> Stop Tightening It.
>
> you are supposed to really crank those bolts down first time you put them on. after that, ive
> heard a second retightening after a while doesnt hurt. but becuase of the way the crank is
> attached to the spindle, i believe the metal deforms just a wee bit, and although it is still
> firmyl on there, the *bolt* will be looser than you left it. just leave it like that. if you keep
> re-tightening it, you can split the crank arm over the spindle. or so i've heard.
>
> check the archives in the long threads about greasing spindle tapers for stories about people who
> retighten their crank bolts again and again and eventually split them.

This doesnt' apply to splined BBs. They seat against a stop. You should put a torque wrench on them
to check the torque.

David

 

On Sat, 24 May 2003 03:08:42 GMT, [email protected] wrote:

>forward as I am. That's why I don't have these cranks. Shimano apparently knows about this and come
>up with another idea in their latest cranks that do not use this system as we see in:
>
>http://tinyurl.com/cdxe
>
>Jobst Brandt [email protected] Palo Alto CA

I wonder what effect having the bearings outboard of the shell has on the chainline...

I know the XTR model in the same style has a fixed chainline of 50mm

G

 

[email protected] (Chris Zacho "The Wheelman") wrote in message
news:<[email protected]>...
> Not meaning to make you sound stupid, but are you sure you've torqued the bolts tight enough?
>
> I've never worked with the splined BB's Partly because, IMO, they're just another attempt by
> Shimano to be different (read: incompatible).
>
> May you have the wind at your back. And a really low gear for the hills! Chris
>
> Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

Hi if the crank still keeps working loose after a good tightening then maybe the square insert on
the crank itself has worn. This happened to me a few times despite tightening the crank many times.
The only solution was to buy a new crank. Dave Miles

 

Dave Miles writes:

>> Not meaning to make you sound stupid, but are you sure you've torqued the bolts tight enough?

>> I've never worked with the splined BB's Partly because, IMO, they're just another attempt by
>> Shimano to be different (read: incompatible).

> Hi if the crank still keeps working loose after a good tightening then maybe the square insert on
> the crank itself has worn. This happened to me a few times despite tightening the crank many
> times. The only solution was to buy a new crank.

Please explain. What square insert? This is a spline drive with tapered cylinder hollow spindle. I
believe the cause for its loosening has been explained. What is it that you think occurs?

Jobst Brandt [email protected] Palo Alto CA

 

On Mon, 26 May 2003 18:51:59 GMT, [email protected] wrote:
>Dave Miles writes:
>
>> Hi if the crank still keeps working loose after a good tightening then maybe the square insert on
>> the crank itself has worn. This happened to me a few times despite tightening the crank many
>> times. The only solution was to buy a new crank.
>
>Please explain. What square insert? This is a spline drive with tapered cylinder hollow spindle. I
>believe the cause for its loosening has been explained. What is it that you think occurs?

The splined cranks and BB magically transform themselves into regular tapered square pegs & holes?
Or maybe, and I realise this must be a novel concept for you, he just made a mistake.

Jasper