...me money.
My until-then-100%-reliable Nexus-fitted Ridgeback Nemesis blotted its copy book a few weeks ago, when, following a rear tyre replacement, the fixing nut holding the back (hub) brake came loose. The back brake then fell apart; I put it back together but it didn't work very well, so I replaced it.
To ensure that I'd done the fixing nut up to the right torque,
[Wurzels accent]Oi Got A Brand New...[/Wurzels accent]
torque wrench.
This evening, I undid the chainring bolts, removed and cleaned the front chainring, and put it all back together. But, in a rare omission, it appears that Shimano have forgotten to put the chainring bolt torque on the instruction leaflet. All the other nuts and bolts have a torque value to be done up to, varying from 0.7 to 50 Nm. (My torque wrench only does 5 to 25 Nm!)
So, for FC-S500, a 45-tooth single-speed front chainwheel with single-sided chain guard, how many Newton metres should I put on the bolts? Normally, I'd tighten it till it felt "about right", but now that I've got a torque wrench, I feel I ought to use it.
Careless torque costs...
Careless torque costs...
"Little Green Men Are Everywhere... ...But Mostly On Traffic Lights."
Sealey STW101 1/4" drive. In a nice plastic box to keep it clean. And a machine-oil-stained (for authenticity!) calibration certificate. I'd already got quite a collection of 1/4" sockets.
BUT most nuts/bolts for which those lovely Shimano people specify a torque setting are actually allen bolts. So I found myself in Screwfix, and they don't do 1/4" drive allen keys, but they had quite a cheap set of 3/8" drive ones. Which work fine with my 1/4" to 3/8" adaptor.
For some nuts, (such as the above-mentioned brake fixing nut on the rear roller brake) I need a long-reach socket. So that one hasn't been properly torqued up!
The torque wrench gives a noticeable 'click' when it gets to the right force.
It's purely a luxury purchase. If I were a proper engineer I'd know these things from just the feel of them.
BUT most nuts/bolts for which those lovely Shimano people specify a torque setting are actually allen bolts. So I found myself in Screwfix, and they don't do 1/4" drive allen keys, but they had quite a cheap set of 3/8" drive ones. Which work fine with my 1/4" to 3/8" adaptor.
For some nuts, (such as the above-mentioned brake fixing nut on the rear roller brake) I need a long-reach socket. So that one hasn't been properly torqued up!
The torque wrench gives a noticeable 'click' when it gets to the right force.
It's purely a luxury purchase. If I were a proper engineer I'd know these things from just the feel of them.
"Little Green Men Are Everywhere... ...But Mostly On Traffic Lights."
Torque wrench! A torque wrench! 
Eh I remember when I wert nobbut a lad we didnt need no torque wrench, we just tightened it up until it stripped then backed it off a quarter of a turn..... ah the good old days when just a pair of pliers and a pair of mole grips were all we needed.......... none o this soft torque wrench nonsense!
Your not from the South are you:wink:
Eh I remember when I wert nobbut a lad we didnt need no torque wrench, we just tightened it up until it stripped then backed it off a quarter of a turn..... ah the good old days when just a pair of pliers and a pair of mole grips were all we needed.......... none o this soft torque wrench nonsense!
Your not from the South are you:wink:
Biscuit wrote:generic "it's tough oop north" oldie rant
'Appen! From T'fens originally, now in T'midlands. I live north of the Trent, which I treat as the dividing line between North and South. (As did Shakespeare - read Henry IV part 1!)
If money were (almost) no object, what Luxury Item would you have in your Toolbox? Apart from pliers and mole grips?
"Little Green Men Are Everywhere... ...But Mostly On Traffic Lights."
-
Colin Stanley
- Posts: 323
- Joined: 12 May 2007, 7:05pm
- Location: Somewhere in Kent
If a softie southerner might interject....
You could always use a spring balance on the end on whatever lever arm you are using at the time. Then a subtle calculation to bring it to Nm.
Yes, why is it that ahead handle bar extension thingies quote a ridiculously low torque for their ‘alien’ screws, which no self respecting car torque wrench would ever register. Looking on the www, there appears to be no torque wrench that would cover a bike's bits.
So, what do folk use?
Don’t fob me off with ‘I know how much the screw needs and feel the amount’. C’mon, I am a mechanical engineer, and have worked on a Hillman Imp engine (a quarter of the H16 racing block – being aluminium alloy, had to use a torque wrench or reach for the Helicoils...).
I always guess my chainring bolts tightness
You could always use a spring balance on the end on whatever lever arm you are using at the time. Then a subtle calculation to bring it to Nm.
Yes, why is it that ahead handle bar extension thingies quote a ridiculously low torque for their ‘alien’ screws, which no self respecting car torque wrench would ever register. Looking on the www, there appears to be no torque wrench that would cover a bike's bits.
So, what do folk use?
Don’t fob me off with ‘I know how much the screw needs and feel the amount’. C’mon, I am a mechanical engineer, and have worked on a Hillman Imp engine (a quarter of the H16 racing block – being aluminium alloy, had to use a torque wrench or reach for the Helicoils...).
I always guess my chainring bolts tightness
-
thirdcrank
- Posts: 36781
- Joined: 9 Jan 2007, 2:44pm
Colin Stanley wrote:Looking on the www, there appears to be no torque wrench that would cover a bike's bits.
Chevin Cycles
By coincidence, I was having a nosey in Chevin Cycles, Otley, last week (Not my lbs.) They had 'cycling specific' torque wrenches on sale. I did not look closely because most of my amateurish mechanicking days are behind me. Searched there www and could not find it on there, but they definitely had two or three (all the same model) on display. Quite bijou - I had a little play with one but still could not bring myself to shell out.
(If you google cycle torque wrench you get several hits.)
-
Colin Stanley
- Posts: 323
- Joined: 12 May 2007, 7:05pm
- Location: Somewhere in Kent
