Do torque measurements matter on brakes?

evade

Hey all,

I'm just beginning to get my hands dirty with my bikes, so I'm afraid I've got a bit of a stupid rookie question for you... :roll:

I've just bought some disc brakes from the forum, to put onto my old hardtail. The instructions are talking about torque measurements for the rotors and for the calipers. After spending more than I wanted to on the brakes, I'm not totally happy spending another £35 on a torque wrench this month if I don't really need to. So... do these measurements really matter all that much on these components? I'm only planning to do road work on the hardtail.

Cheers
Evade

diy

There are tables on the net which will give you a ready reckoner of load based on the length of your wrench, but given that these don't squeeze up anything, like say a crank, headset or bearing, then torque settings are less important.

I would google a conversion table just to get a feel for how much it feels like.

Dirtydog11

evade wrote:

Hey all,

So... do these measurements really matter all that much on these components? I'm only planning to do road work on the hardtail.

Cheers
Evade

Only if you undertighten or overtighten them.

diy

As a rough guide Nm / 2 = KG at 15cm

So 400 inch pounds, around 50kg = 25kg on a 6 inch wrench...

very rough this..

Note also that you might have a cordless drill with a torque setting.

iain1775

on things like disc rotors some threadlock on the bolts is probably more important than accurate torque setting
On things like bottom brackets, suspension pivots, crank arms, stem bolts etc then torque becomes more important, especially if you are using things like carbon bars etc

IMO It is actually quite suprising how low the torque settings on various bike componants are when you install with a torque wrench, without you are far more likely to overtighten things than undertighten.

glauciaregina9

I don't consider a torque wrench essential for stuff like caliper mounts and disc rotors - I've never used a torque wrench for these, just tightened until it feels about right... you're unlikely to do any damage to these areas (unless you're bolting to a carbon mounting perhaps).

One thing I recommend though: always put a small amount of grease on the disc rotor bolts. You'll probably rarely undo them, so a bit of grease makes future removal a whole lot easier.


For things like stem bolts and crank/bottom bracket fitting I usually do use a torque wrench as these generally seem more sensitive to over/under-tightening.


Always use a torque wrench for carbon parts as carbon has more specific tolerances to crushing and so on.

glauciaregina9

iain1775 wrote:

on things like disc rotors some threadlock on the bolts is probably more important than accurate torque setting...

Heh.

One reader recommends threadlock, I recommend a bit of grease... :?

Ah well.


From my experience, I have never had a disc rotor bolt come loose, but I have had them become so stuck that I've stripped the head trying to remove them and had to resort to filing flats on the head to get a small spanner onto... which seriously scratches the rotor... now you don't wanna be doing that

diy

that tip on greasing is good - I personally dip every bolt in copper grease when installing it. Just a tiny bit on the end and the thread will do the distribution.

evade

Brilliant, cheers for your help chaps.

Evade

evade

Brilliant, cheers for your help chaps.

Evade

evade

Brilliant, cheers for your help chaps.

Evade

evade

Brilliant, cheers for your help chaps.

Evade