U-Lock Woes

U-locked bike
Example of a properly U-locked bike (just don’t forget your key!).

You come out to your locked bike and are in a hurry to get to class.  You quickly jam your key in the lock, try to turn it and it just doesn’t want to turn, so you turn harder, and harder til “SNAP” it goes and now you have to walk or take the bus.  ARRGGHHH!

Does this scenario sound familiar?  Well, you’re not alone.  The good news is that this headache is preventable with a little forethought.

According to a bunch of people who work with thousands of bikes on campuses around the country it seems that virtually every U-lock made will eventually develop rust inside the lock.   When you add ice to the rusty mess opening U-locks can become very frustrating not to mention expensive if you break your key.

Thanks to one of those campus bike specialists,  John Brandt, here’s your solution to eliminating your ‘U-lock Woes’:

The simple solution I’ve found is to put an occasional drop of heavy oil on the moving parts of the locking mechanism that engage the u-bar portion of the lock.  Some of the lube may find its way back into the lock tumblers, but in every case I’ve worked on it’s the sliding-locking-bar/pin that was the problem.  Simple lubrication seems to prevent the problem from ever occurring and usually fixes it if it does.

Lubing a U-lock - pic 1
Where to lube your U-lock.

Specifically:

  • take the lock apart into its two parts
  • set the u-portion aside, it’s just an inert piece of metal
  • turn the key to make the lock mechanism move to the locked position
  • as you turn the key, look into the holes where the u-portion fits
  • some u-locks will only lock one side, other will lock at both ends (photo shows a one-sided mechanism)
  • drip several drops of machine oil (or chain lube) onto the part that you see moving when you turn the key; this is the sliding-locking-bar/pin that engages the u-portion (see photo below)
  • work the key back and forth a few times to get the oil between the moving parts
  • once they move smoothly again, the key should no longer bind and you’re good to go

Even with a frozen/stuck u-lock, there is one thing you can try as long as the key isn’t broken off in the lock and unable to be removed.  Squirt copious amounts of a thin penetrating oil (like WD-40) down the tiny seams where the u-portion enters both sides of the bar of the u-lock (see photo below).  Do it on both sides and don’t be shy with the amount; flood it good.  Squirt a tiny bit right into the keyhole, too, just in case.  If you’re willing to wait a few minutes for the oil to penetrate, you may find that the key turns again if you start by gently wiggling it back and forth to help the oil penetrate even further.  That works on better than 90% of the stuck locks I’ve worked on.  I do not use thin oils like WD-40 to lube locks once they’re working again; it washes off too quickly so I use a heavy lube for that.

Lubing a U-lock - pic 2
Where to lube a U-lock for preventative maintenance.

For preventive maintenance:

  • Check your lock whenever you lube your chain
  • If the turning key seems to bind or turn stiffly, re-lube those parts (you already have your lube in your hand)
  • Prevention is key.  If you leave your bicycle outside in the rain a lot, lube the lock more often;  the more it rains, the more often you should re-lube the mechanism
  • I use a non-greasy lube (Poxylube) for my keyholes so my key doesn’t always come out greasy and stain my pockets( http://www.locksmithledger.com/product/10288074/sandstrom-products-poxyluber-cp200 ), but I prefer a heavy lube for the mechanism because it doesn’t wash off as fast.  (MSU Bikes sells Pedro’s Syn Lube which is a great heavier lube for both your lock and your chain)

My bikes don’t live outside 24/7 like many others do, but I lube all my locks once a year and I’ve never had a problem with any of my u-locks in over 20 years.

John Brandt
Safety, Security & Transportation Manager
The Universities at Shady Grove, MD

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Author: Tim Potter

Sustainable Transportation Manager, MSU Bikes Service Center; member of the All University Traffic & Transportation Committee (http://auttc.msu.edu); founding member of MSU Bike Advisory Committee (https://msubikes.wordpress.com/volunteer-donate/msu-bac/); advocate for local & regional non-motorized transportation issues thru the Tri-Co. Bike Assn. Advocacy Committee (http://groups.google.com/group/tcatc); board member of the Ride of Silence (http://www.rideofsilence.org); year-round bicyclist of all sorts; photographer; soccer player; father of 3; married 30 yrs. to Hiromi, Japanese national (daughter of former Natl. Keirin Champion, Seiichi Nishiji); Christ follower.

2 thoughts on “U-Lock Woes”

  1. Thanks for posting that Bob. Very helpful to visualize these things. Just replied to an email from a student w/ a jammed U-lock. I wouldn’t use WD-40 however. It’s good at breaking up rust but it’s not a lasting lubricant. We’ve found that most sticky/ rusty U-locks just need basic oiling which helps to break up the rust and get the lock tumbler moving smoothly again, so buy some good bike chain oil (like Tri-Flow, or Finish Line, or any number of other good chain oils sold in bike shops) and use that instead. You can also use it on your bike chain as a bonus, which every bicyclist needs to do regularly (at least monthly if not more often).

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