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Torque Wrench

Bruce ThorntonBruce Thornton Posts: 87
edited September 2012 in Workshop
I'm about to change my veloce double for a centeur compact. My mate has lent me a park bb tool which is for Shmano but it still fits the Campag cups. I'd like opinions on if I should invest in a torque wrench. I've looked into it find they can be quite expensive about £50to£100 or cheap ones about £30 are these ok or should I spend a bit more. Can anyone recommend what to go for. One other question about the cup removal tool should I buy the Campag one or again go for a cheaper one

Posts

  • You don't need a torque wrench to do a BB... Torque wrenches are needed for low torque values rather than high. Do it tight, no need to struggle, just do it tight... If it is 35 or 50 rather than 40 nM it makes no difference whatsoever
  • richaricha Posts: 1,633
    You don't need a torque wrench to do a BB... Torque wrenches are needed for low torque values rather than high. Do it tight, no need to struggle, just do it tight... If it is 35 or 50 rather than 40 nM it makes no difference whatsoever
    Is that also true for Sram GXP? I plan to start swapping cranks a bit.
    Rich
  • rolf_frolf_f Posts: 16,015
    For a BB you'd need a big torque wrench. For almost everything else you need a small one.

    I do have a big torque wrench which I use for cassette fitting. It isn't accurate (because of the knurled cap to the cassette rings) but that doesn't matter (as Ugo explained) - but what it does do is mean that I always tighten the cassette to the same amount - which isn't too tight that I wreck the tool trying to get the cassette off next time (which, obviously, I did!!).

    The big torque wrench cost £15 from Lidl so not really a huge investment!
    Faster than a tent.......
  • Coach HCoach H Posts: 1,092
    For BB's, unless you get a torque wrench that releases for LH and RH threads (ie expensive and difficult to source) you will only be able to get the correct torque on one cup anyway (assumisng you don't have an Italian BB).

    I use a torque wrench but Ugo's advice is not bad for BB's
    Coach H. (Dont ask me for training advice - 'It's not about the bike')
  • RichA wrote:
    You don't need a torque wrench to do a BB... Torque wrenches are needed for low torque values rather than high. Do it tight, no need to struggle, just do it tight... If it is 35 or 50 rather than 40 nM it makes no difference whatsoever
    Is that also true for Sram GXP? I plan to start swapping cranks a bit.

    It's valid for every steel or hard alloy part that requires mid-high torque values... 20-50 Nm

    Torque wrenches were a niche of the aviation industry, then the car industry and only recently entered the bicycle market. Basically they are a licence for manufacturers to build underengineered parts, typically made of carbon fibre or soft alloys. They give very strict torque settings, which in practice common torque wrenches cannot meet anyway.
    In the avaition industry these tools were calibrated methodically and very often, while chances are the one you end up buying can't even be recalibrated... hence it might work for a few months, but then it's probably worse than your hand "feel". Most modern cheap tools are made in china and they are junk, especially precision tools, like Vernier calipers, torque wrenches etc... when I raided my granfather workshop I did find some proper tools, which were incredibly expensive to buy, but the engineering was remarkable.
    These days: Park tools are OK, but nothing outstanding... at least they are durable. Nothing compares with a 1980s Campagnolo tool for fitting and removing bottom bracket cups... it was an incredibly well designed tool and only busy workshops could afford one...

    Moral: you get what you pay for... if you want a good torque wrench, spend money, otherwise do without
  • MccariaMccaria Posts: 869
    I have a small torque wrench for carbon bits and then a bigger one for the BB. The bigger one is not absolutely essential - after you've fitted a couple of BB you get the feel of how much force to exert. If you can borrow one and practice a couple of times, you will probably get the feel and not need the wrench - the BB is not as sensitive as carbon parts.

    Not sure I undestand Coach H's point on the different cup threads. Wrenches have a tightening and a loosening function, so just flip it around for the different cup threads and it works fine ?
  • Coach HCoach H Posts: 1,092
    Mccaria wrote:
    Not sure I undestand Coach H's point on the different cup threads. Wrenches have a tightening and a loosening function, so just flip it around for the different cup threads and it works fine ?

    Both of mine (both middle range Teng Tools professional) only release at the set torque in one direction. Yes they both are able to tighten and loosen in both directions but not release. I found this out when waiting for the click only to strip out a nice soft torx bolt that tightened anti-clockwise. Only then did I test the release in this direction using the bolt I have fixed to my workbench, which is used to warm up my wrenches for more consistent release.
    Coach H. (Dont ask me for training advice - 'It's not about the bike')
  • MccariaMccaria Posts: 869
    Ouch, painful way to find out !
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