Help needed fitting a new stem.

[Walrus]

I posted this in "Equipment" but you guys are so responsive, I thought I'd post it here as well...

I just bought a new stem (Ritchey WCS 26) for my LOOK road bike. I have a alloy steerer tube and carbon handlebars. I want to know whether
a) it's a good idea for me to fit this myself
b) if so, what tools do I need.

My concern is that I might tighten the bolts too tight and crack the carbon handlebar. Am I right in saying that a torque wrench lets you tighten something to a certain point that won't damage other components? Is this what I need?

I'm trying to learn more about maintaining my own bioke, but should I just take this to my LBS and get them to do it?

 

[flyingdutch]

give it to me!

I know ALL_ABOUT_CF!!!

hear lots of (possibly urban myth) stories about peoples cracking/crunching CF bars/seatposts due to overtightening.
There's a lil number next to the bolts on my stem (120nM or sumfin like that). Im assuming that is a torque wrench measurement/number?
Presumably your stem came with something similar (or their website?)

So, we gonna see this LOOK out on BR one day, huh, huh, huh ???

 

[Walrus]

give it to me!

I know ALL_ABOUT_CF!!!

hear lots of (possibly urban myth) stories about peoples cracking/crunching CF bars/seatposts due to overtightening.
There's a lil number next to the bolts on my stem (120nM or sumfin like that). Im assuming that is a torque wrench measurement/number?
Presumably your stem came with something similar (or their website?)

So, we gonna see this LOOK out on BR one day, huh, huh, huh ???

I hope so, I have an 8 week old baby boy, so my ride time is very rare. I tend to ride with some other mates when I get the chance. I do want to join you guys though.

 

[retrograded]

"Walrus" <[email protected]> wrote in message
news:[email protected]...
>
> I posted this in "Equipment" but you guys are so responsive, I thought
> I'd post it here as well...
>
> I just bought a new stem (Ritchey WCS 26) for my LOOK road bike. I have
> a alloy steerer tube and carbon handlebars. I want to know whether
> a) it's a good idea for me to fit this myself
> b) if so, what tools do I need.
>
> My concern is that I might tighten the bolts too tight and crack the
> carbon handlebar. Am I right in saying that a torque wrench lets you
> tighten something to a certain point that won't damage other
> components? Is this what I need?
>
> I'm trying to learn more about maintaining my own bioke, but should I
> just take this to my LBS and get them to do it?
>
>
> --
> Walrus
>

Does the CF bar have a torque rating?

I know nothing about CF handlebars so forgive me if that is a silly
question, but I'm assuming it would as it would most likely be the part to
fail if it was subjected to a lot of pressure. If it does have a torque
rating (it would read something like 120Nm), then a torque wrench would be
the most sensible and safe option for installing the bar. I have stripped
threads in a very expensive stem due to excessive torque, and I subsequently
went out to buy a torque wrench. Err on the side of caution and but a torque
wrench, they cost peanuts compared to a new CF handlebar.

 

[Claes]

"Walrus" <[email protected]> wrote in message
news:[email protected]...
>
> I posted this in "Equipment" but you guys are so responsive, I thought
> I'd post it here as well...
>
> I just bought a new stem (Ritchey WCS 26) for my LOOK road bike. I have
> a alloy steerer tube and carbon handlebars. I want to know whether
> a) it's a good idea for me to fit this myself
> b) if so, what tools do I need.
>
> My concern is that I might tighten the bolts too tight and crack the
> carbon handlebar. Am I right in saying that a torque wrench lets you
> tighten something to a certain point that won't damage other
> components? Is this what I need?
>
> I'm trying to learn more about maintaining my own bioke, but should I
> just take this to my LBS and get them to do it?
>
>
> --
> Walrus
>

Does the CF bar have a torque rating?

I know nothing about CF handlebars so forgive me if that is a silly
question, but I'm assuming it would as it would most likely be the part to
fail if it was subjected to a lot of pressure. If it does have a torque
rating (it would read something like 120Nm), then a torque wrench would be
the most sensible and safe option for installing the bar. I have stripped
threads in a very expensive stem due to excessive torque, and I subsequently
went out to buy a torque wrench. Err on the side of caution and but a torque
wrench, they cost peanuts compared to a new CF handlebar.

The value will be something in the range of 10 Nm, 120 Nm is prolly twice of what you tighten a wheel nut on car to. Anyway, if you have no feel for this, or no torque meter, then you might wanna have your LBS do it. Somehow I do not think they will use a torque meter though.

 

[suzyj]

Dutchy wrote:

> hear lots of (possibly urban myth) stories about peoples
> cracking/crunching CF bars/seatposts due to overtightening.

It's not overtightening per-se that damages carbon parts, it's sharp edges cutting into the carbon that does them in.

Carbon parts don't have the same amount of surface toughness that aluminium or steel parts do, as the surface is simply epoxy (plastic). So if there's anything that's vaguely sharp, like burrs or sharp corners, it will cut into the carbon fairly quickly.

This is most evident with steel frames, where the binder bolt is right at the top of the seat lug. When you flogg (important technical term for do up really tight) the binder bolt up, the square corners at the back top of the seat lug press into the post, and may cut into it. The solution is to move the binder bolt down a tad (kinda difficult to do with a frame that's already built) and round the offending corner out a little, so that it's not so sharp.

So with your stem, forget the torque wrench - the correct torque is where the stem and bars don't slip. Instead, pull out a bit of emery paper and make sure there are no burrs that will cut into the bars. Also round the edges a little, again to ensure edges don't cut in. When you do the bolts up, do it progressively, so that you don't pinch the bars.

Regards,

Suzy (likes carbon seatposts and forks and stuff)

 

[retrograded]

"Claes" <[email protected]> wrote in message
news:[email protected]...
>
> retrograded Wrote:
>> "Walrus" <[email protected]> wrote in
>> message
>> news:[email protected]...
>> >
>> > I posted this in "Equipment" but you guys are so responsive, I
>> thought
>> > I'd post it here as well...
>> >
>> > I just bought a new stem (Ritchey WCS 26) for my LOOK road bike. I
>> have
>> > a alloy steerer tube and carbon handlebars. I want to know whether
>> > a) it's a good idea for me to fit this myself
>> > b) if so, what tools do I need.
>> >
>> > My concern is that I might tighten the bolts too tight and crack the
>> > carbon handlebar. Am I right in saying that a torque wrench lets you
>> > tighten something to a certain point that won't damage other
>> > components? Is this what I need?
>> >
>> > I'm trying to learn more about maintaining my own bioke, but should
>> I
>> > just take this to my LBS and get them to do it?
>> >
>> >
>> > --
>> > Walrus
>> >
>>
>> Does the CF bar have a torque rating?
>>
>> I know nothing about CF handlebars so forgive me if that is a silly
>> question, but I'm assuming it would as it would most likely be the part
>> to
>> fail if it was subjected to a lot of pressure. If it does have a
>> torque
>> rating (it would read something like 120Nm), then a torque wrench would
>> be
>> the most sensible and safe option for installing the bar. I have
>> stripped
>> threads in a very expensive stem due to excessive torque, and I
>> subsequently
>> went out to buy a torque wrench. Err on the side of caution and but a
>> torque
>> wrench, they cost peanuts compared to a new CF handlebar.
> The value will be something in the range of 10 Nm, 120 Nm is prolly
> twice of what you tighten a wheel nut on car to.

Good point, I was really using 120Nm as an example, sorry to original poster
for any confusion.

Anyway, if you have
> no feel for this, or no torque meter, then you might wanna have your LBS
> do it. Somehow I do not think they will use a torque meter though.
>
>
> --
> Claes
>

 

[Resound]

"flyingdutch" <[email protected]> wrote in
message news:[email protected]...
>
> give it to me!
>
> I know ALL_ABOUT_CF!!!
>
> hear lots of (possibly urban myth) stories about peoples
> cracking/crunching CF bars/seatposts due to overtightening.
> There's a lil number next to the bolts on my stem (120nM or sumfin like
> that). Im assuming that is a torque wrench measurement/number?
> Presumably your stem came with something similar (or their website?)
>
> So, we gonna see this LOOK out on BR one day, huh, huh, huh ???
>
>
> --
> flyingdutch
>

120 newton/metres is a fairly hefty torque figure. I'm not saying it's
definitely wrong or anything, but on a generalised hauling on a spanner
scale, you'd be fairly leaning on it.

 

[Claes]

"flyingdutch" <[email protected]> wrote in
message news:[email protected]...
>
> give it to me!
>
> I know ALL_ABOUT_CF!!!
>
> hear lots of (possibly urban myth) stories about peoples
> cracking/crunching CF bars/seatposts due to overtightening.
> There's a lil number next to the bolts on my stem (120nM or sumfin like
> that). Im assuming that is a torque wrench measurement/number?
> Presumably your stem came with something similar (or their website?)
>
> So, we gonna see this LOOK out on BR one day, huh, huh, huh ???
>
>
> --
> flyingdutch
>

120 newton/metres is a fairly hefty torque figure. I'm not saying it's
definitely wrong or anything, but on a generalised hauling on a spanner
scale, you'd be fairly leaning on it.

Yeah, a simple way to figure this out and get some feel for it is this, or
rather, this is how I do it.
120 Nm, means 120 N force applied to a 1 meter lever. Assume the lever is parallel to the ground, and the gravity induced acceleration is 10 m/s^2, it is 9.81 or something, it means hanging a weight of 12 kg on the end of that 1 meter bar. Say your wrench is a third of a meter, or roughly 33 cm, a BIG wrench, that equals 36 kg on the bar then. That is how I find some sort of "feel" to how hard I tighten things. If you have gone to a gym, well you get your dumbells and stuff there so you somewhat of a feel for 5 kgs and such. Anyway, sorry for the rant.

Back to the stem, my stem allows 12 Nm, say my hex tool has a lever of 10 cm, that means 12 kg from that puny thing. You can not apply that without getting serious pain in your hands.