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Pedal problem

Hi there! Beginners question here - I've looked on Park Tools and can't find an answer.

I have an MTB (Decathlon Rockrider ST120), and in the past few days, I've felt a tiny bit of movement on the left pedal, only when I'm standing and riding hard. I've tightened the pedal up, but that didn't make a difference. Any ideas what else it could be if it's just the left pedal?


  • When you say you have tightened the pedal up, do you mean into the crank arm? If that is tight then most likely that the pedal axle itself has got some play.
    You don't state which type of pedals you have so difficult to know if they are serviceable/adjustable
  • JBAJBA Posts: 2,852
    You need to determine if the play is in the pedal (not so bad) or the crank arm (potentially much worse).
    What pedals and chainset do you have?
    “Life has been unfaithful
    And it all promised so so much”

    Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Toughtroad SLR 1 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 2009
  • reaperactualreaperactual Posts: 1,162
    Unlikely the pedal axle in the crank arm. Between the axle and pedal body there is a bearing/s of some kind where the play is coming from.

    Having said that fitted pedals are usually cheap and don't last very long in most cases anyway so maybe worth getting something decent as a first upgrade which are worth your time and the cost.
  • Thanks all for your quick replies :)

    Yes, I tightened up the part right next to the pedal itself, where it attaches to the crank arm. It's the pedal that came with the bike (a basic plastic one). The chainset is also the one that came with the bike. Here are a couple of photos if that helps:

  • reaperactualreaperactual Posts: 1,162
    edited January 2021
    Grab the left pedal with one hand and the crank arm with the other then push pedal, pull it, rotate it and compare with doing the same with the right pedal and you should notice any differences.

    If the bike is fairly new doubt it will be the bb or cranks yet but test by grabbing each crank arm and try to rock the centre spindle to hear or feel for movement to rule that out as the cause.

    If it's the left pedal you could try opening it up using basic tools and service it. Simply pulling it apart and putting it back together properly after doing a basic clean and re grease may work, e.g:-

    They are cheap basic pedals by the look of it so maybe think about spendind around £20-30 buying some decent quality replacements. Loads of good quality choices in that price range so worth looking into.

  • JBAJBA Posts: 2,852
    Looks like a fairly basic square taper crank set.
    Before you start stripping the pedals make sure the bolts that hold the cranks arms on to the bottom bracket are tight. If they come loose and are left for too long the taper in the crank arm wears and you'll never get it tight again.
    “Life has been unfaithful
    And it all promised so so much”

    Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Toughtroad SLR 1 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 2009
  • So here's what I've done, I held the crank and tried to move the pedal every which way. There's a *tiny* bit of movement, but it's the same on both pedals, so that's probably ok.

    I held both cranks and tried to move the whole thing, and no movement at all. I put an allen key on both sides of the thing connecting the two cranks (is that the bottom bracket?) and it was already as tight as it could go.

    I should say, the movement on the pedal when I'm cycling is the tiniest thing - and only when I'm standing and pushing hard.

    Does all of that suggest it might be a problem inside the pedal?
  • Lower cost pedals often have a bit of movement in them, just ignore it until they wear out or you decide to upgrade.
  • steve_sordysteve_sordy Posts: 2,417
    edited January 2021
    Judging by the picture of the pedal, they probably cost about £5 in the shop (probably 50p to make). They are provided so that you can test ride the bike (good luck with that these days!), or to just ride the bike out of the shop. You could keep replacing them, but I would advise that you don't. Compare the pins on your pedal with those on the pedal in the video. The pedal in the video has metal pins that penetrate your sole and provide great grip. The plastic nubbins on your pedal don't do that, they rely on snagging on any tread there may be on the sole of your riding shoes. Get a pair of proper flats and upgrade your ride.

    There is bound to be a thread on here about best pedals, use the search function. But I'd start here and go from there.
  • Wonderful! Thank you so much! I'll have a look at some nice flats. I have flats on my other bike, and they do rip my ankles, but they grip much better.

    I'll have a look through that thread, but realistically, £15/20 pedals aren't going to be much good are they?
  • The HT PA03A looks like the one for me!
  • reaperactualreaperactual Posts: 1,162
    edited January 2021
    w7london said:

    I'll have a look through that thread, but realistically, £15/20 pedals aren't going to be much good are they?

    Those HT seem a good choice, for a good price and are going to be 100 times better than the ones you have now. 😎👍

    Spending this kind of money is going to get you good pedals and they're worth every penny.

    My personal favourites are Nukeproof Electrons, my set are still going strong after 2 years of abuse and they only cost £22 on sale at the time.

  • Thanks so much everyone for your help and support on this one :star: I'll let you know how the new pedals go. I just changed the tyres and tubes on both wheels (I've been getting punctures about twice a week this month). Got some Smart Sams and Schwalbe tubes. Fingers crossed!
  • steve_sordysteve_sordy Posts: 2,417
    Ref the punctures:
    Either use Slime tubes and never get another flat, but they are heavy.
    Or go tubeless with sealant and never get another flat, lower your tyre pressure and get a smoother ride, a faster ride over rough ground, and lighter too.

    Going tubeless is a bit harder than an expert makes it look, but a lot easier than a beginner makes it look.
  • With Slime tubes, do you still need to patch the hole when you get home (is the slime just to get you home, or does the slime actually fix it totally)?

    I usually keep the tyres at around 45psi because most of my riding is on road, and I find that lower pressures are a lot slower.
  • steve_sordysteve_sordy Posts: 2,417
    Firstly, you won't even realise that you have had a puncture! There may be a green spot (Slime is fluorescent green), but mostly not. Just ride the bike.

    However, when you come to change a tyre you have a choice. Inspect the tube and you will see lots of evidence where a puncture has occurred. Inspect the tyre and you may see thorns still sticking through. If you will be using the tyre again, remove the thorns with a pair of pliers. If you decide to use the tube again because it has been holding pressure satisfactorily, then again you have a choice. Leave it as is, or apply patches to where the tube was punctured. If you opt for this route, then be sure to clean all traces of the Slime from the tube before trying to patch it. Just wiping it off will not be good enough, you need to use some iso-propyl alcohol (IPA ) or some brake cleaner which is very similar. No IPA, then use meths.

    Ref pressures: High pressure is good for smooth surfaces, because it reduces rolling resistance. But for rougher surfaces, lower pressure tyres actually have a lower rolling résistance. This is because the low pressure tyre conforms to the rock or root, providing some suspension and allowing the wheel to roll forward more smoothly. A high pressure tyre bounces back off the obstacle and slows you down, as well as feeling rough.

    You have to decide what the majority of your ride requires and you will have to compromise. Some riders who ride tarmac to get to a trail pump up the tyre for the tarmac, reduce pressure for the trail, then restore pressure for the tarmac ride home.
  • So an update: last week, the small movement on the pedal turned in to a massive crunching sound on both pedals. It got to the point where the crank would barely turn. (I don't know if it was the pedal problem, or if there was a separate issue inside the pedal)

    I took it to the shop and straight away they said it was bottom bracket. They replaced it because the bearings had gone (on a 4 month old bike).

    So there we go.
  • webboowebboo Posts: 5,477
    If the cranks wouldn’t turn it would be the bottom bracket.
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