I am fed up with cheap allen keys. I've bought a few from local hardware stores, but a 5mm is usually way off, and I end up rounding off the key, or the bolt. I've thought about buying this parks allen key:


It has 5 star review from 5 customers at the moment, but I'm still wary. Anyone have any experience with it? Or is it just junk that they slapped a parks tool sticker on?

Also, if anyone has any advice on allen keys from their experience I'd love to hear. Is it worth paying for Snap-on keys, or something similar?

I'd love to hear others have this problem too, and it's not just me that can't loosen or tighten a brake lever without rounding something off.

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    This site is not for product recommendations and for sure for not for judging if link is knock off.
    – paparazzo
    Feb 12, 2015 at 2:35
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    There is a good question in here along the lines of "Are workshop quality Allan keys any better than cheap ones"
    – mattnz
    Feb 12, 2015 at 2:45
  • @mattnz thanks for cleaning up my question and making it more stackexchange acceptable.
    – TreK
    Feb 12, 2015 at 2:46
  • My dirt cheep 5mm has begun loosing it's (nickel) plating after only one year of (ab)use, so I doubt a bit the "lifetime" thing. Maybe 10 years (== lifetime for people who hate helmets).
    – Vorac
    Feb 12, 2015 at 11:32
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    I have to believe that either you're using a 5mm when you need a 6, or you're not inserting it fully into the bolt. Even a cheap Allen wrench should not be rounding off or rounding off the bolt if it's the right size and fully inserted. That's the beauty of the Allen design. Feb 12, 2015 at 14:50

4 Answers 4


I have never had a problem with Allen keys rounding. Using the correct size, using them correctly (Inserting them fully and not letting them slip out the bolt) and not using too much torque for the bolt size means even cheap Allen keys will last a lifetime.

If the bolt head has rusted or has gunk in it, you sometimes cannot easily get the Allen key in all the way. In this case cleaning the hole is required. Abusing the bolt/allen key by only inserting it part way is the most likely cause of problems. Workshop quality tools will survive abuse such as this (although it's more likely the bolt won't).

If you are having problems rounding the Allen keys, workshop quality tools to likely just move this problem to the bolt, making it a much bigger problem.

  • If it's the bolts that are stripping instead of the tool, make sure you have the right size wrench and insert it all the way in.
    – xpda
    Feb 12, 2015 at 3:49
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    @xpda: Rust and gunk often makes life not so simple. Feb 12, 2015 at 4:43
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    It's faster in the long run to take the time to clean it out.
    – xpda
    Feb 12, 2015 at 5:29
  • Except that sometimes, inexpensive allen keys are not made exactly to spec. This is especially true if they are provided with some other product. This is usually immediately obvious because there's play the very first time it's inserted. The solution is to throw those examples away and use one that is in spec. Also, I keep a scratch awl in my shop specifically for cleaning out socket-head screws, both allen and Torx. Feb 13, 2015 at 16:49

All other things being equal, T-shaped Allen wrenches will work better than L-shaped Allen wrenches.

When I say T-shaped Allen wrenches, I'm talking about wrenches like these:

Park Tool PH-2

as well as the 3-way hex wrenches like the one you mention:

Park Tool AWS-15

This is because the shape of these tools allows you to exert pressure from directly above the bolt rather than from the side. Exerting pressure from the side adds a lever element which can cause the tool to slip. Pressure from directly above the bolt keeps the tool held fast without that side leverage.

That's not to say that L-shaped wrenches don't have their place. They're typically much easier to get into tighter places. As others have mentioned, high quality L-shaped Allen wrenches will often have a rounded head at one end, which makes it easier to get at bolts from an angle.

Rounded Allen wrenches

It seems counter-intuitive, but these rounded heads actually hold a bolt very well. I can't recall ever having one slip (with the exceptions of already stripped bolts and/or user stupidity).

As far as Park Tools go, they are well respected in the bicycle industry as offering the highest quality tools available. That's not to say they're the only game in town. There are lots of companies that offer high quality Allen wrenches. If you don't trust Park Tools for whatever reason, buy your Allen wrenches from any high quality source that you do trust.

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    I disagree. Although the T handles you show are superior to the 3-way designs, they still can't get into many tight spots. I think it's very, very difficult to improve on the L-shaped design, which is why you'll find nothing else in a machine shop. Feb 14, 2015 at 1:47
  • I did say, "That's not to say that L-shaped wrenches don't have their place. They're typically much easier to get into tighter places." That's why you find both in bike shops.
    – jimchristie
    Feb 14, 2015 at 3:38

If you are referring to getting to the brake lever bolt from an angle because it is behind the cable then that is when the ball end comes in handy

Hex bolt in back of brake lever behind cable

If the bolt is dirty the ball end also penetrates a little better but cleaning the bolt is the better path

hex ball end

Use the regular end when you can come in straight for more contact area

Even straight on I will use the round end when the bolt is loose as it is faster - you don't have to be perfectly straight on


FWIW, I have found allen wrenches that have a ball end to generally be of higher quality and less likely to round off. My experience is that generally the wrench fails long before the bolt.

If the wrench gets rounded off, you need to stop using it ASAP.

If you are doing lot's of your own bike work, it's worth investing in a set of T-handled allen wrenches.

Bondhus Allen wrenchs

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    But the ball end tools have a smaller contact area. I'm not sure the typical improved quality is enough to offset this. That said I tend to use my ball end set at home anyway - unless I need a lot of torque.
    – Chris H
    Feb 12, 2015 at 10:43
  • Agreed. Having that length is also very useful for those hard-to-reach tasks
    – PeteH
    Feb 12, 2015 at 12:36
  • The trouble with the T handles is there are many bolts on a bike where that handle is hugely in the way. Try removing a water bottle cage with one of those, for example. Plain old Allen wrenches without T handles have no such limitation, and they can be used in two orientations. Much more useful tools, IMO. Feb 12, 2015 at 14:54

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