How tight should it be !?!?!

[Gilders]

Hi - complete novice with a question about how tight I should be fixing brake calipers to fork and frame. I would really appreciate input from those who are in the know and able to make me a bit less incompetent...(!)

I gather there's a wonderful invention called a torque wrench which can solve this problem, but in the absence of one, is there any basic rule-of-tightening-thumb I can follow, e.g number of allen key turns, etc?

Also;

(1) Should it be possible to move the brake caliper off-centre by force of hand alone? If I can, does this mean it's not attached to the frame tightly enough?

(2) Does it make any difference as to how tight the brake caliper can be attached if the fork is made of carbon?

(3) Will I be causing untold damage to either componentry or frame if bolts are (slightly?) under-tight?

Many thanks to any of you out there who can help and look forward to hearing from you.

G

 

[boudreaux]

Originally posted by Gilders
Hi - complete novice with a question about how tight I should be fixing brake calipers to fork and frame. I would really appreciate input from those who are in the know and able to make me a bit less incompetent...(!)

I gather there's a wonderful invention called a torque wrench which can solve this problem, but in the absence of one, is there any basic rule-of-tightening-thumb I can follow, e.g number of allen key turns, etc?

Also;

(1) Should it be possible to move the brake caliper off-centre by force of hand alone? If I can, does this mean it's not attached to the frame tightly enough?

(2) Does it make any difference as to how tight the brake caliper can be attached if the fork is made of carbon?

(3) Will I be causing untold damage to either componentry or frame if bolts are (slightly?) under-tight?

Many thanks to any of you out there who can help and look forward to hearing from you.

G

It needs to be tight enough so the caliper does not rotate and loose centering when using the brakes. Not so tight that somethng gets hosed.

 

[daveornee]

Originally posted by Gilders
Hi - complete novice with a question about how tight I should be fixing brake calipers to fork and frame. I would really appreciate input from those who are in the know and able to make me a bit less incompetent...(!)

I gather there's a wonderful invention called a torque wrench which can solve this problem, but in the absence of one, is there any basic rule-of-tightening-thumb I can follow, e.g number of allen key turns, etc?

Also;

(1) Should it be possible to move the brake caliper off-centre by force of hand alone? If I can, does this mean it's not attached to the frame tightly enough?

(2) Does it make any difference as to how tight the brake caliper can be attached if the fork is made of carbon?

(3) Will I be causing untold damage to either componentry or frame if bolts are (slightly?) under-tight?

Many thanks to any of you out there who can help and look forward to hearing from you.

G

Installation of the brake itself
Tightening torque:
8 – 10 Nm {69 – 87 in. lbs.}
per http://bike.shimano.com/product_images/BR/si_images/BR-770065005500_SI.pdf
You can look on the Shimano site for your particular brake, as this is for the current Ultegra brake.

 

[DiabloScott]

OK torque is force times distance (ignoring any bending moment) so 80 inch pounds is the force of 80 pounds on a 1 inch long allen wrench or 40 pounds on a 2 inch long allen wrench. You'll probably still get it wrong but at least it's something to shoot for.

I wish torque wrenches were cheaper too. Friend of mine got a good set at the hardware store though, not bike specific but good enough for almost all applications.

 

[boudreaux]

Originally posted by DiabloScott
OK torque is force times distance (ignoring any bending moment) so 80 inch pounds is the force of 80 pounds on a 1 inch long allen wrench or 40 pounds on a 2 inch long allen wrench. You'll probably still get it wrong but at least it's something to shoot for.

I wish torque wrenches were cheaper too. Friend of mine got a good set at the hardware store though, not bike specific but good enough for almost all applications.

Tightening a nut is not exactly rocket science. What is a bike specific torque wrench anyway? Ft pounds, inch pounds and Nms are all pretty universal.

 

[Gilders]

Many thanks people - appreciate all the input given. Just (unnecessarily?) worried about causing damage through either over or undertightening. After all, it's not as if I can just lightly push the bloody caliper and it moves...

Any recommendations for decent - and decently-priced - torque wrenches warmly received.

Cheers!

 

[DiabloScott]

Originally posted by boudreaux
Tightening a nut is not exactly rocket science. What is a bike specific torque wrench anyway? Ft pounds, inch pounds and Nms are all pretty universal.

Bike specific means that it's designed for use on the relatively small nuts and bolts and relatively tight places that a bike mechanic needs it for - the set my friend got has some parts that a bike mechanic will never need. And some of the wrenches have indicators that interfere with operating the tool in some locations. Things you might not think about until you have to use them.

 

[boudreaux]

Originally posted by Gilders [/i

Any recommendations for decent - and decently-priced - torque wrenches warmly received.

Cheers!

Craftsman at Sears Roebuck

 

[boudreaux]

Originally posted by DiabloScott
Bike specific means that it's designed for use on the relatively small nuts and bolts and relatively tight places that a bike mechanic needs it for - the set my friend got has some parts that a bike mechanic will never need. And some of the wrenches have indicators that interfere with operating the tool in some locations. Things you might not think about until you have to use them.

One can buy the Torque wrench and the other stuff separately.