Using a torque wrench?

summerdays

Cycling in the sun
Location
Bristol
Thanks to @Pat "5mph" posting about the wiggle offer on a torque wrench, I now have one.

I know the value is marked on my seat post clamp, but where do I find other values? And my saddle slips unless it's done up very tightly, too tightly for me to normally do up and stop it from slipping. Can I tell what it is currently done up to using my wrench? Or what would be the suggested value for it (a specialized saddle?)
 

Asa Post

Small lungs, weak legs
Location
Sheffield
Thanks to @Pat "5mph" posting about the wiggle offer on a torque wrench, I now have one.

I know the value is marked on my seat post clamp, but where do I find other values? And my saddle slips unless it's done up very tightly, too tightly for me to normally do up and stop it from slipping. Can I tell what it is currently done up to using my wrench? Or what would be the suggested value for it (a specialized saddle?)
Park Tools have recommended values here.
Or, there's an alternative list here.

To test the current value of the seat post bolt, undo the bolt with the torque wrench and note the value at which the bolt starts to turn.
 
OP
summerdays

summerdays

Cycling in the sun
Location
Bristol
Park Tools have recommended values here.
Or, there's an alternative list here.

To test the current value of the seat post bolt, undo the bolt with the torque wrench and note the value at which the bolt starts to turn.
Thank you

I did wonder if I could do that... So I would try turning the bolt and keep using the torque until it moved?
 
[QUOTE 4014209, member: 9609"]I would think that would be a highly unreliable way of assessing what the value is? If it has recently been tightened I would imaging it would slacken off at a much lower torque, and if it has been on for ages and seized you may get a stupidly high value.
Neither of the torque wrenches I have at home work anticlockwise so can't experiment.[/QUOTE]


Agreed. Plus you shouldn't assume it had been tightened to the correct torque in the first place. I've lost track of the brand new Halfords bikes I've been asked to look at which had barely finger tight brake pads and other loose bits............
 

RichardB

Slightly retro
Location
West Wales
A beam-type torque wrench will tell you the loosening torque quite happily (it even has a dual scale for the purpose), although as above there are many reasons why this may not be the correct value. Out of sheer laziness, I sometimes use my torque wrench to undo bolts without setting any torque value, and it will remove reasonably firm bolts in this condition. That suggests to me that it doesn't work in the same way when loosening and tightening, and so any attempt to get a torque reading while loosening a bolt is not going to give a reliable result.

Slightly off-topic, but in the world of auto engineering, critical torque values are specified for threads which are dry or oiled/greased. If you oil or grease a thread and then torque it up when it is specified 'dry', you will over-torque it and risk stripping the thread. That might be critical if you are working on soft alloy, although I don't know if the principle is adhered to in bicycle mechanics. Just throwing the idea in, really.
 
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Pat "5mph"

A kilogrammicaly challenged woman
Moderator
Location
Glasgow
Thanks for the tips all, I have so far only used a torque wrench on a bike mechanic's class.
Will experiment with my newly acquired one, maybe watch a few YouTube videos too.
 
OP
summerdays

summerdays

Cycling in the sun
Location
Bristol
Thanks, I'm glad I asked, there is more to it than I realised!
 

Pat "5mph"

A kilogrammicaly challenged woman
Moderator
Location
Glasgow
@summerdays I have also got one for the big values - cranks and whatnot, got it from Halfords on a sale a while back, it's a Park Tool.
I paid half of the price in the link, actually less because there was a 3 for 2 offer on.
Truly, I had made a mistake, did not realize this was a big value wrench, really wanted the small value one ... erm ... a girl cannot have too many tools.
You can see this model is different, you calibrate it by moving the dial to zero by hand.
 

Milkfloat

Veteran
Location
Midlands
Assuming it is the lifeline version then it won't work anti-clockwise. If the post still slips after applying the right torque then I would make sure it is grease free and use some carbon paste.

Failing that, say bollocks to it and just keep tightening until it does not slip. :smile:
 
OP
summerdays

summerdays

Cycling in the sun
Location
Bristol
Assuming it is the lifeline version then it won't work anti-clockwise. If the post still slips after applying the right torque then I would make sure it is grease free and use some carbon paste.

Failing that, say bollocks to it and just keep tightening until it does not slip. :smile:
Not the seat post, I can do that one up fine, it's the saddle clamp... If I do it up, it will suddenly give way and suddenly it's facing skyward. Last time it happened a stranger on my commute did it up for me and it hasn't shifted since but it's in the wrong place.
 

Milkfloat

Veteran
Location
Midlands
Unless they are carbon rails I would go to 11 on a scale of 1-10. Well maybe not that much, but I would go nice and tight but not so much as to strip threads.
 

RichardB

Slightly retro
Location
West Wales
I would go nice and tight but not so much as to strip threads.
Which is the whole point of having a torque wrench! ^_^ With experience, it's quite easy to guess when something is 'tight enough', but without that experience it's easy to under or over-tighten something, with potentially costly results either way. I'm still occasionally stripping threads, and I have been spannering for 40+ years :smile:

I generally work to some very precise torque settings:

Finger-tight
Nipped up
Snug
Tight
Very tight
Really very tight indeed
[Insert foul oath of choice] tight
Both hands and it hurts your arms tight
Six-foot cheater bar and get your wife to hold the thing steady cos your feet are off the floor tight.
As above, but with two adults hanging off the cheater bar.

The last one was the crankshaft bolt on my Land Rover, and the one before was the gearbox sprocket nut on my Yamaha. I've only ever used the first four on a bicycle.
 
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