what do people do for tightening pedals - torque and carbon

ben-----
ben----- Posts: 573
edited October 2013 in Road buying advice
Hello, I'm in the process of putting my new bike together (only a few things needed doing - seat, seat post, pedals etc.). All this carbon and torque stuff is new to me and I'm scared of doing some costly damage. What do people do for putting pedals on if the cranks are carbon? An open ended spanner is required. But torque wrenches aren't like that. The pedal and chainring leaflet that came with the bike says, for pedals, tighten to 39-49 Nm / 345-435 in.lbs. That seems incredibly tight, compared to what the seat post clamp is supposed to be (6.2-8Nm / 55-71 in-lbf). Anyway, irrespective of tightness, what's the best (i.e. least costly) tool to use for this. Thanks.

Comments

  • gozzy
    gozzy Posts: 640
    I don't have carbon cranks, but I don't think you need to worry to much about damaging them, I think the worst you could do is scratch them with the edge of a spanner.
    Personally, I'd just do it up with a spanner that fits, till it's all the way in and not worry about torqueing it up.
    I use a cone spanner or an adjustable spanner depending on how easily it fits. You can get pedal spanners, but I've never needed one.
    Pedal threads are designed so that they'll tighten with normal use rather than loosening so there's no need to worry about them coming undone.
    Just make sure you put plenty of grease on the threads - I'm assuming the crank threads will be alloy bonded into the carbon.
  • slowbike
    slowbike Posts: 8,498
    I've only ever nipped up my pedals - that'll be far less than 39-49Nm (40Nm for the cassette lock ring) suggested.
    Pedals are designed to do up when pedalling - ie they won't undo unless you pedal backwards for ages!

    If you've got a torque wrench then use it on a normal bolt in a vice and feel what 40Nm is ... then do the pedals up less than that ...
  • jordan_217
    jordan_217 Posts: 2,580
    Go on feel. If your knuckles turn white under the tightening force, then it's too tight. It's not that hard to achieve that torque with a spanner (more leverage). Add a touch of grease to the pedal axle threads too.

    Use a torque wrench for everything else. A Ritchey torque key is a handy and relatively cheap tool for tightening stem and bar clamps, it's 'pre-dialled' to 5Nm which is good enough for most applications. Carbon assembly paste is also handy for stopping the seat post from slipping, hairspray is a cheaper alternative.

    If in doubt go to your LBS, a mistake could be costly....
    “Training is like fighting with a gorilla. You don’t stop when you’re tired. You stop when the gorilla is tired.”
  • ben-----
    ben----- Posts: 573
    > I don't think you need to worry to much about damaging them, I think the worst you could do is scratch them with the edge of a spanner

    But it's the fact that its compression (rather than bending) isn't it? Carbon isn't so strong in that way, so that's the danger. That's how I understand it anyway.

    > If you've got a torque wrench then use it on a normal bolt in a vice and feel what 40Nm is ... then do the pedals up less than that ...

    That's a good idea. Thanks. I just found this http://toolstoday.co.uk/product/9811/te ... -m386515-c but it seems that under-tightening won't be a problem - that fact, and the above bit of advice, I reckon I'll just use a normal spanner.

    Thanks.
  • bobones
    bobones Posts: 1,215
    You should be using pedal washers on carbon cranks and then tighten the pedals up pretty tight.
  • gozzy
    gozzy Posts: 640
    ben----- wrote:
    > I don't think you need to worry to much about damaging them, I think the worst you could do is scratch them with the edge of a spanner

    But it's the fact that its compression (rather than bending) isn't it? Carbon isn't so strong in that way, so that's the danger. That's how I understand it anyway.

    I meant you might do some cosmetic damage, if you're worried about that then wrap some cloth around the cranks while you fit the pedals.
    Realistically, you're not going to break your cranks by fitting some pedals. There's certainly no need to do them up to the torque levels suggested. Just grease the threads, make sure the thread goes in ok and do it up till it's all the way in. Then ride off into the sunset...
  • ben-----
    ben----- Posts: 573
    > You should be using pedal washers on carbon cranks

    Yup, I've got those, they were elastic banded to one of the cranks. Thanks.

    > Realistically, you're not going to break your cranks by fitting some pedals. There's certainly no need to do them up to the torque levels suggested. Just grease the threads, make sure the thread goes in ok and do it up till it's all the way in. Then ride off into the sunset...

    Right, I see. Great, thanks.
  • Bozman
    Bozman Posts: 2,518
    As mentioned previously, I just nip the pedals up and put a bit of grease on the threads with Look pedals on FSA slk light and SRAM red cranks.
  • cattytown
    cattytown Posts: 647
    Have a look at the end of the pedal spindles. Some have a hex socket for use with an allen key, e.g. http://cdn.velonews.competitor.com/file ... 11/DA3.jpg

    Paul.
    Giant Defy 2
    Large bloke getting smaller :-)
  • There is no reason to torque the pedals, hand tight with the pedal spanner is fine. As you pedal, they will tighten themselves
    left the forum March 2023
  • Coach H
    Coach H Posts: 1,092
    There is no reason to torque the pedals, hand tight with the pedal spanner is fine. As you pedal, they will tighten themselves

    I used to think this until in the middle of nowhere I found the source of the click that had been plaguing me for a few rides. Non-drive sire pedal was about halfway out with no fix until home apart from doing up finger tight (no allen bolt on rear of spindle).

    Although on the flip side I have also suffered the curse of jammed pedals as well :roll:
    Coach H. (Dont ask me for training advice - 'It's not about the bike')
  • keef66
    keef66 Posts: 13,123
    Coach H wrote:
    There is no reason to torque the pedals, hand tight with the pedal spanner is fine. As you pedal, they will tighten themselves

    I used to think this until in the middle of nowhere I found the source of the click that had been plaguing me for a few rides. Non-drive sire pedal was about halfway out with no fix until home apart from doing up finger tight (no allen bolt on rear of spindle).

    Although on the flip side I have also suffered the curse of jammed pedals as well :roll:

    I too have known pedals come undone because they were not adequately tightened. Because they are near to the road surface and sprayed with salty crap in winter I use copperslip on pedal axle threads, and just do them up tight with a pedal spanner. I remove and refit them every year or so; never had a seized one doing this.
  • Coach H
    Coach H Posts: 1,092
    keef66 wrote:
    Coach H wrote:
    There is no reason to torque the pedals, hand tight with the pedal spanner is fine. As you pedal, they will tighten themselves

    I used to think this until in the middle of nowhere I found the source of the click that had been plaguing me for a few rides. Non-drive sire pedal was about halfway out with no fix until home apart from doing up finger tight (no allen bolt on rear of spindle).

    Although on the flip side I have also suffered the curse of jammed pedals as well :roll:

    I too have known pedals come undone because they were not adequately tightened. Because they are near to the road surface and sprayed with salty crap in winter I use copperslip on pedal axle threads, and just do them up tight with a pedal spanner. I remove and refit them every year or so; never had a seized one doing this.

    To be fair, I always use anti-sieze and plenty of it however a well known LBS in the North West didn't think it was worth it leading to stuck pedal. At least I assume they he didn't put any on as I never did get it off, but the other one was certainly fitted dry.

    I have to say the loose pedal started out pretty tight and I am well known amongst friends for overtightening everything; perhaps just one of those things.
    Coach H. (Dont ask me for training advice - 'It's not about the bike')
  • neeb
    neeb Posts: 4,470
    Firstly, don't worry at all about the fact that the cranks are carbon, they are designed to withstand massive forces from pedalling and the threads are metal obviously. You only really need to worry about damaging carbon by over-tightening when you are compressing lightweight, hollow tubes with clamps, such as a frame tube, seatpost, steerer, bars etc.

    I also once found myself with a pedal coming undone in the middle of nowhere and ended up having to buy a monkey wrench from a garage to get home safely, so I now do them up pretty tight - if you are using a long-handled pedal spanner, that would be moderate force but not using all of your strength, if that makes sense.