Shimano compact crank: Torx driver for bolts, torque?
Harry Crumm
sure my chainring bolts are tight.
It's a Shimano compact crankset, FC-6750.
Can anyone point me to three pieces of information:
1. What size Torx driver do I need for the chainring bolts?
2. What is the torque spec for the chainring bolts?
3. Any recommendation for a set of Torx drivers for my 1/4" drive
torque wrench?
Thanks.
thirty-six
From the methode d'estructions.
Tightening torque:
12 - 16 N·m {106 - 139 in. lbs
Seems a bit much.
Michael Press
<8eb0202c-0cd9-41c7...@y31g2000vbt.googlegroups.com>,
Harry Crumm <misterha...@gmail.com> wrote:
Hardware stores in the USA typically sell them individually.
As for your ticking noise, use all your ingenuity and
powers of observation to track down the source of the
noise, and do not distract yourself tinkering with stuff.
Remember that the noise can come from anywhere.
--
Michael Press
Harry Crumm
> From the methode d'estructions.
>
> Tightening torque:
> 12 - 16 N·m {106 - 139 in. lbs
>
> Seems a bit much.
Can you tell me what "methode d'estructions" you are referencing, and
how to get a copy of this document?
The tech docs I've seen on the Shimano web site are not specific on
either the Torx driver or the torque.
Thanks.
Lou Holtman
> On Oct 1, 5:40 pm, thirty-six<thirty-...@live.co.uk> wrote:
>
>> From the methode d'estructions.
>>
>> Tightening torque:
>>
>> Seems a bit much.
>
> Can you tell me what "methode d'estructions" you are referencing, and
> how to get a copy of this document?
>
> The tech docs I've seen on the Shimano web site are not specific on
> either the Torx driver or the torque.
>
> Thanks.
Torx 30.
Lou
Harry Crumm
>
> <http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_...>
>
> Torx 30.
>
> Lou
Thanks, Lou.
Ronko
100c40...@y31g2000vbt.googlegroups.com>,
misterha...@gmail.com says...
it occur at this spot regardless of what gear you are in, although it
may occur more readily with more pedaling force applied? If so then
it sounds like the cups need to be reinstalled and tightened more
than they are now.
thirty-six
> On Oct 1, 5:40 pm, thirty-six <thirty-...@live.co.uk> wrote:
>
> > From the methode d'estructions.
>
> > Tightening torque:
> > 12 - 16 N·m {106 - 139 in. lbs
>
> > Seems a bit much.
>
> Can you tell me what "methode d'estructions" you are referencing, and
> how to get a copy of this document?
google - instructions FC-6750
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_1LJ0A_001/SI-1LJ0A-001-ENG_v1_m56577569830671266.pdf
or Technical Service Instructions SI-1LJ0A-001
>
> The tech docs I've seen on the Shimano web site are not specific on
> either the Torx driver or the torque.
I dont see the fastener size but the torque requirement is clear,
"With the marked surface of the smaller
chainring facing away from the crank arm,
set the chainring so that the o mark is lined
up with the crank arm position.
Tightening torque:
12 - 16 N·m {106 - 139 in. lbs.}"
As I said seems a little high, more than a regular chainring fastening
torque. I don't know why, I am not familiar with it. Your suspicions
could well be warranted. It would be understandable if only regular
fastening torque was used, and so may be the cause of your noise.
Good luck.
>
> Thanks.
Harry Crumm
> Does the ticking occur at a certain spot in the crank revolution? Does
> it occur at this spot regardless of what gear you are in, although it
> may occur more readily with more pedaling force applied?
Yes and yes. The tick seems to emanate from the right (chainring)
side, between the top of the pedal stroke and 1/4 forward, regardless
of the gear, and only while standing.
> If so then
> it sounds like the cups need to be reinstalled and tightened more
> than they are now.
Very possible.
Thanks.
Harry Crumm
> google - instructions FC-6750http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_1LJ0A_...
> or Technical Service Instructions SI-1LJ0A-001
>
>
>
> > The tech docs I've seen on the Shimano web site are not specific on
> > either the Torx driver or the torque.
>
> I dont see the fastener size but the torque requirement is clear,
> "With the marked surface of the smaller
> chainring facing away from the crank arm,
> set the chainring so that the o mark is lined
> up with the crank arm position.
> Tightening torque:
> 12 - 16 N·m {106 - 139 in. lbs.}"
>
> As I said seems a little high, more than a regular chainring fastening
> torque. I don't know why, I am not familiar with it. Your suspicions
> could well be warranted. It would be understandable if only regular
> fastening torque was used, and so may be the cause of your noise.
> Good luck.
>
Many thanks for the reference.
Before tightening the bolts, I will try to determine their current
tightness with a torque wrench. This will give me the general ballpark
for their current tightness, and I'll compare this reading to the
specs in the documents that you and Lou referenced. (It seems unlikely
that they are all significantly loose. It seems more likely that one
or two bolts might be a bit looser than the others.) Not a scientific
procedure, of course. I wish Shimano had an email address to send
these kinds of questions to.
Harry Crumm
> Harry Crumm <misterharrycr...@gmail.com> considered Fri, 1 Oct 2010
> rotation is an inadequately secure aglet.
Not sure what you mean. What is an aglet?
Rob Lindauer
>>
>> In my experience, the commonest cause of ticking in time with pedal
>> rotation is an inadequately secure aglet.
>
> Not sure what you mean. What is an aglet?
He was teasing (although it's undoubtedly often true). An aglet is the
tip of a shoelace. -RL
--
Rob Lindauer - for my real email, change "att" to "sbc"
thirty-six
Just back them off a 1/4 turn and use the preset wrench at the right
value, anything not setting at the original position, you then know
was wrong. If the click disappears, then the incorrect fastening
torque was significant.
Loose or damaged pedal bearings also produce a tick as you load them,
but I've always been able to detect this by feel in my foot.
Lou Holtman
Geezz, why make it so complicated? Remove chainrings, grease every metal
to metal contact reinstall chainrings and torque to spec and be done
with it. It is not rocket science. If it still ticks the chainrings are
not the problem.
Lou,
thirty-six
If you want to bother with that, then a scraper should be taken to
each joint to remove any burrs.
Andre Jute
You hardware store sells bits in kits and individually. With torx bits
it is important to get good quality bits so you don't rip up the torx
sockets; i.e. not the cheap stuff in cheap kits. My T20 torx bits for
working on my expensive Rohloff hub gearbox are by Witte of Germany,
recommended by a hardware guy I've dealt with for twenty years and
specially bought in by him for me because the builders who're his
biggest customers find the cheaper but still very good C&K bits suit
them. About seven or eight bucks US per pair of bits; I have one in
every toolkit that comes near that bike, plus a couple of spares. Of
course, a set of chainring bolts isn't as expensive as a Rohloff
gearbox, so you could probably justify getting a standard good brand
from a reliable hardware shop. I like the CK brand for good but not
overpriced tools, and top American tool brands are also excellent and
not always as pricey as the German brands. -- AJ
Andre Jute
BTW, It's probably your crank bolts that need tightening. Creaks from
that region are usually caused by the crank bolts loosening. The
normal tools required for that on modern bikes are an 8mm hex bit and
a torque wrench that can handle up to c35Nm. You should look up the
precise torque spec for your components as they can differ. (I have
steel cranks and torque the crank bolts to 33Nm.) If memory serves,
Jobst Brandt, an engineering authority on bikes, claims that you
shouldn't retorque cranks onto square BB axles but instead take the
assembly apart and grease it first; his reason might make sense but I
can't recall them now. Yahoo snubs to Jobst. I retorqued my creaking
crank last night -- it required an eighth turn with the torque wrench
on boths side and the creak is fixed, with no observable deleterious
effects. -- AJ
Jay Beattie
> In article
> <8eb0202c-0cd9-41c7-ad5a-100c40163...@y31g2000vbt.googlegroups.com>,
> Harry Crumm <misterharrycr...@gmail.com> wrote:
>
> > I'm chasing down a ticking noise in my drivetrain and want to make
> > sure my chainring bolts are tight.
>
> > It's a Shimano compact crankset, FC-6750.
>
> > Can anyone point me to three pieces of information:
>
> > 1. What size Torx driver do I need for the chainring bolts?
> > 2. What is the torque spec for the chainring bolts?
> > 3. Any recommendation for a set of Torx drivers for my 1/4" drive
> > torque wrench?
>
> Hardware stores in the USA typically sell them individually.
>
> As for your ticking noise, use all your ingenuity and
> powers of observation to track down the source of the
> noise, and do not distract yourself tinkering with stuff.
> Remember that the noise can come from anywhere.
And usually not the chainrings. That is about the most benign
interface on the bike. -- Jay Beattie.
Jay Beattie
Dear Andre, (where is Carl, BTW), the FC-6750 is a two piece crank
and has no crank bolts. It has two pinch bolts.
http://www.performancebike.com/bikes/Product_10052_10551_1076711_-1_51000_20000_51003
I do not know why the manufacturer spec'd Torx bolts since retaining
chainrings is not a high torque application and means you need to
carry yet another wrench in your seat pack just in case -- or just no
worry about it. -- Jay Beattie.
Andre Jute
> Dear Andre,
Oh, dear, Jay,
>(where is Carl, BTW),
Dear Carl fell into a googlehole in Arizona. Good riddance to a
dishonest and immoral shit.
>the FC-6750 is a two piece crank
> and has no crank bolts. It has two pinch bolts.http://www.performancebike.com/bikes/Product_10052_10551_1076711_-1_5...
Thank you for this information. If you expect me to be embarrassed by
my ignorance, forget it. I leave that sort of hubris to engineers and
others who like to pretend they know everything. i rejoice everytime
someone tells me something I didn't know.
> I do not know why the manufacturer spec'd Torx bolts since retaining
> chainrings is not a high torque application and means you need to
> carry yet another wrench in your seat pack just in case -- or just no
> worry about it. -- Jay Beattie.
Torx bolts/screws are proliferating. First it was only T25 on disc
brakes. Then, when the better multitools included T25, suddenly
Rohloff standardized on T20, which of course was in no multitool. Then
the brake people also added T8, and didn't I read T30 mentioned in
connection with chainrings. It's a nightmare. And meanwhile fender
struts still have nuts and bolts, and racks have nuts. So you have to
carry hex bits, torx bits, spanners or sockets for nuts -- and there
goes simplicity. My Kranich appears to have been specially designed to
minimize the number of tools required, but the (heavy, Teutonic,
everlasting, expensive) multitool provided 'free' with the bike, while
it has everything else, still doesn't have a T20 for the Rohoff... And
if you have a Brooks saddle you must carry two tools for it, one the
tensioning spanner, which is too fragile to tighten the seatpost
clamp, and a 1/2 socket (and something to drive it with) for the clamp
nut (unless you have strong fingers, in fact you need 2x half-inch
sockets!).
Andre Jute
That trivia is not trivial weight, even for a non-roadie
Jobst Brandt
>>> I'm chasing down a ticking noise in my drivetrain and want to make
>>> sure my chainring bolts are tight.
>>> It's a Shimano compact crankset, FC-6750.
>>> Can anyone point me to three pieces of information:
>>> 1. What size Torx driver do I need for the chainring bolts?
>>> 2. What is the torque spec for the chainring bolts?
>>> 3. Any recommendation for a set of Torx drivers for my 1/4" drive
>>> torque wrench?
>> BTW, It's probably your crank bolts that need tightening. Creaks
>> from that region are usually caused by the crank bolts loosening.
>> The normal tools required for that on modern bikes are an 8mm hex
>> bit and a torque wrench that can handle up to c35Nm. You should
>> look up the precise torque spec for your components as they can
>> differ. (I have steel cranks and torque the crank bolts to 33Nm.)
>> If memory serves, Jobst Brandt, an engineering authority on bikes,
>> claims that you shouldn't re-torque cranks onto square BB axles but
>> instead take the assembly apart and grease it first; his reason
>> might make sense but I can't recall them now. Yahoo snubs to
>> Jobst. I re-torqued my creaking crank last night -- it required an
>> eighth turn with the torque wrench on both sides and the creak is
>> fixed, with no observable deleterious effects.
Look at split cranks on the failure web site and you'll see why
re-tightening crank-spindle bolts is a bad practice. When cranks flex
under pedaling loads, they squirm away from the flat bolt-head and
creep up the taper, leaving the retention bolt looser than it was when
properly tightened. This process occurs repetitively until the crank
splits in two diagonally across the square bore.
http://pardo.net/bike/pic/fail-001/FAIL-001.html#crank-fail-011
> Dear Andre, (where is Carl, BTW), the FC-6750 is a two piece crank
> and has no crank bolts. It has two pinch bolts.
The pinch-bolt method is a response to those who spit cranks by
repeated tightening.
> I do not know why the manufacturer spec'd Torx bolts since retaining
> chainrings is not a high torque application and means you need to
> carry yet another wrench in your seat pack just in case -- or just no
> worry about it.
You don't need to tighten these screws.
Jobst Brandt
Jobst Brandt
>>> I'm chasing down a ticking noise in my drivetrain and want to make
>>> sure my chainring bolts are tight.
>>> It's a Shimano compact crankset, FC-6750.
>>> Can anyone point me to three pieces of information:
>>> 1. What size Torx driver do I need for the chainring bolts?
>>> 2. What is the torque spec for the chainring bolts?
>>> 3. Any recommendation for a set of Torx drivers for my 1/4" drive
>>> torque wrench?
>> BTW, It's probably your crank bolts that need tightening. Creaks
>> from that region are usually caused by the crank bolts loosening.
>> The normal tools required for that on modern bikes are an 8mm hex
>> bit and a torque wrench that can handle up to c35Nm. You should
>> look up the precise torque spec for your components as they can
>> differ. (I have steel cranks and torque the crank bolts to 33Nm.)
>> If memory serves, Jobst Brandt, an engineering authority on bikes,
>> claims that you shouldn't re-torque cranks onto square BB axles but
>> instead take the assembly apart and grease it first; his reason
>> might make sense but I can't recall them now. Yahoo snubs to
>> Jobst. I re-torqued my creaking crank last night -- it required an
>> eighth turn with the torque wrench on both sides and the creak is
>> fixed, with no observable deleterious effects.
Look at split cranks on the failure web site and you'll see why
re-tightening crank-spindle bolts is a bad practice. When cranks flex
under pedaling loads, they squirm away from the flat bolt-head and
creep up the taper, leaving the retention bolt looser than it was when
properly tightened. This process occurs repetitively until the crank
splits in two diagonally across the square bore.
http://pardo.net/bike/pic/fail-001/FAIL-001.html#crank-fail-011
> Dear Andre, (where is Carl, BTW), the FC-6750 is a two piece crank
> and has no crank bolts. It has two pinch bolts.
The pinch-bolt method is a response to those who split cranks by
repeated tightening among other reasons.
> I do not know why the manufacturer spec'd Torx bolts since retaining
> chainrings is not a high torque application and means you need to
> carry yet another wrench in your seat pack just in case -- or just no
> worry about it.
You don't need to tighten these screws.
Jobst Brandt
Michael Press
<17746be3-b83b-457b...@a15g2000yqm.googlegroups.com>,
Jay Beattie <jbea...@lindsayhart.com> wrote:
I actually had chainring bolts go loose.
Bad design, difficult to tighten enough.
The symptom was _not_ ticking. It was
spoon in a garbage disposal when attempting
to shift up front.
--
Michael Press