The barrel adjuster: What it is and why it’s a cyclist’s best friend

The almighty barrel adjuster, so simple, yet so useful for small adjustments!

The barrel adjuster

Next time you are out on a bike ride, squeeze your brake level. When you’ve pulled the lever about 1/4 of the way, the brakes should be engaged. At a half way, they should be fully engaged.

If you’re not finding that’s the case, then you can make small adjustments using the barrel adjuster.

You’ll find the barrel adjuster either on your handlebars, coming out of your brake levers or on the brake arms themselves.

At the start, when your brake pads are new, the barrel adjuster should be fully screwed in to position. However, as your pads wear out, you can twist to move the adjuster out, this will bring the brakes closer to your wheel rims.

Give it a try, and see the difference.

This is a great way of getting better performance out of your brakes, without having to get your hands greasy or get any allen keys out.

There will come a point of course, when your brake pads are too worn out to use. You can see in the picture below, the pad at the top is completely worn out and the pad at the bottom is new. If you keep riding with worn out pads, you’ll damage your wheel rims and hear a scraping sound.

Replacing brake pads is relatively easy. We’ve got instructions for hydraulic disk brakes on the site and our Bike Doctor App (iPhone and Android) has instructions for the most common brake systems.

This is a fairly common repair and depending on how often you ride and the brake system you use, you may have to do it 1-3 times per year.

You’ll also find a barrel adjuster on your rear derailleur, allowing you to adjust your gears. However, that’s a whole other topic, so I’ll save that for a separate blog post.

I’d like to bring more simple maintenance tips like this one to London Cyclist. If you enjoyed it, please leave a comment below. If there’s something that has been mystifying you about your bike, then again, leave a comment below and I’ll see if I can cover it in a future bike maintenance post.

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As seen on The Guardian, BBC and The Independent.

19 Responses to The barrel adjuster: What it is and why it’s a cyclist’s best friend

  1. Morgyface 25/04/2014 at 8:21 am #

    Well, I enjoyed this, really usefull stuff for those of us new to cycling. Please do more.

    • Andreas 25/04/2014 at 1:45 pm #

      Thank you Morgyface – as I’ve got more in to my bike maintenance I forget about the basics sometimes – pleased this article is of use and I’ll plan on publishing more 🙂

  2. ceepeeee 25/04/2014 at 9:34 am #

    I’m not exactly new to cycling but a complete novice at maintenance – this article was very helpful indeed as I had recently noticed that my brakes weren’t working so well and I had to really pull on the levers. I just went out to try your tip and it worked! Like I’ve just fitted new blocks.

    This is the kind of thing that other websites fail to mention – they’re great on more complex repairs and maintenance but forget that some of us need very basic stuff. So thanks.

    • Andreas 25/04/2014 at 1:47 pm #

      You are most welcome! And to think I hesitated before hitting the publish button because I thought I would have been hounded in the comments by people saying “This is too basic – cover more advanced stuff!” Pleased I can help out 🙂

  3. Andrew Wilcox 25/04/2014 at 11:03 am #

    Nice article. Tightened up someone’s yesterday but also needed to do this:

    Its a great check for wheel warping. If you tighten your barrel adjuster and find your brake pads make intermittent contact with the rim, it maybe time to true your wheel.

    Make sure the inside of your brake pads are sitting central in the frame.
    1. Rotate the wheel.
    2. No scraping – tighten the barrel adjuster until they do.
    3. Then tighten and loosen spokes to move the wheel rim away from the brake pad at the point where they contact.
    4. Repeat from 1

    Getting the wheel rim down to a plus/minus 2mm wobble will be good enough perhaps even a bit more if you are in a rush.

    Look at the vertical position of the wheel rim as well. If its gone too elliptical the brake pads will be rubbing the tyres somewhere. Tighten and slacken spokes on both sides of the hub and opposite sides of the wheel to bring it back to circular.

    Slacken off the brake adjuster to get the brake lever positioning mentioned in the article.

  4. Peter 25/04/2014 at 11:32 am #

    don’t forget to screw down the locknut to hold it in the right place (unlike in the photo)

  5. Peter May 25/04/2014 at 4:41 pm #

    here’s a pebble to throw into the pool, with a hub that has been slightly scored the surface area is now greater. Isnt it therefore better than an unscored hub, as a greater surface area means a greater area for the brake pads to bed in and grip?

    • Peter 26/04/2014 at 8:36 am #

      I presume you mean the rum, not the hub. A rim that is not smooth will probably wear down the brake blocks more quickly.

  6. Mrs janet groves 25/04/2014 at 4:44 pm #

    At last.! “Ladybird” bike mechanics that I understand. More please!

  7. Cas Burke 25/04/2014 at 6:48 pm #

    It also helps if you keep your rims and brake block surfaces clean with a monthly wipe-down with vinegar.

  8. Rideon Biketourings 29/04/2014 at 6:28 pm #

    At the shop we would set up linear and disc brakes with slightly more lever travel on the front than the rear. For novice riders this is a simple technique to prevent the inadvertent grabbing of the front brake thus sending the rider over the front of the bike. We also like to thread the barrel adjuster all the in and then back it off two full turns for future maintenance adjusting. Thanks for the article, very nice.

    • Miles 05/07/2014 at 4:42 pm #

      Are you serious? I have been riding bikes for over 30 years and I have NEVER heard of anyone who was able to generate enough force using the front brake to throw them over the handle bars. At worst, overly aggressive use of the front break could make the front wheel loose traction which would almost certainly cause as crash. This is fixed by learning how to use the brakes appropriately for the conditions, not setting the front brake up poorly(in the manner you describe). Needless to say I won’t be using you for my servicing!

      • Colin 05/10/2014 at 8:48 pm #

        Somebody I worked with broke both wrists coming off his bike. He was riding his brand new bike home from work behind somebody else. The traffic lights went to red, the person in front went to go through then changed his mind and stopped, speed and late braking ended up with him going over the handle bars tying to avoid the person in front.

  9. Steph 15/05/2014 at 5:06 pm #

    Yes I have fiddled with this before, but didn’t have a clue what it did. Now I know! Thanks 🙂

  10. Alex Mason 31/05/2014 at 8:23 am #

    For those of us who are never sure which direction to turn the adjuster to tighten or loosen, can you say if tighten= clockwise or anticlockwise? Thanks!

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