While most things like that sound impossibly hard, once you take something apart and figure out how it works it is usually pretty easy to do.
When they introduced these locks I have never been able to pick them using the same techniques that I used to pick the other bike locks that I used to pick as a kid.
I was riding my bike around in the Yaqui Indian community of Guadalupe and found one of these locks that somebody cut off of a bike and threw away so I took it home and figured out how it worked.
OK, I am homeless and don't have a home so I took it to a friends house where I sawed the lock open and took it apart.
First the reason you can't easily pick these locks is that they have some springs which prevents you from reading the locks combination and opening it.
I kind of knew when I first tried to pick on of these locks but after taking the lock apart I proved that.
It looks like the springs push on the combination wheels and prevent them from moving as you try to pick the lock.
Really I think it is a combination of the spring and some shims in the lock, or perhaps better said some of the inner wheels in the lock.
Combination Wheels
Take a look at this combination lock again.Notice it has 5 combination wheels.
When all 5 combination wheels are set to the correct number the lock slides open.
Most of the other bike locks I have seen that look like this one only have 4 combination wheels. But that doesn't make any difference the way the lock works is the same regardless of the number of combination wheels it has.
Also most of the locks I have seen have the numbers 0 thru 9 rather then the letters and numbers this Master Lock has.
Again irregardless of weather the lock has letters, numbers or both on it the principles the locks operate on are the same.
Simple combination wheels on other locks
On those old combination locks you could not change the combination like you can on these newer locks.On the combination locks I used to pick when I was a kid each the combination lock had 4 wheels in it.
Those locks had one combination which could not be changed.
Each wheel was a single wheel with the numbers 0 thru 9 stamped on the outside of the wheel.
Each wheel had a square notch cut in the inside of the wheel.
The notch was cut under a number and that number had to be dialed to open the lock.
When the 4 inside notches were lined up the lock could be slid open.
Say the locks combination was 8435.
Then the first wheel would have a notch cut under the number 8.
The second wheel would have a notch cut under the number 4.
The third wheel would have a notch cut under the number the number 3.
And the last wheel would have a notch cut under the number 5.
3 part combination wheels on these locks
These newer combination locks have wheels where the notch can be moved under any number and thus the locks combination can be changed.When you look at the lock from the outside each wheel looks like a single wheel, but that is not the case.
When you take apart the lock each wheel is really made of three different wheels.
The outside wheel
The outside wheel has numbers or numbers and letters stamped or printed on the outside of it.You use these numbers to dial the combination.
For each number or letter on the outside wheel it has notches on the inside of the wheel.
The notches allow a spring loaded ball bearing to lock the out side wheel to the middle wheel.
The spring loaded ball bearing can be lowered and the out side wheel moved in relation to the middle wheel and thus the combination can be changed.
The middle wheel
The middle wheel has a notch in it.The notch allows the lock to be opened or locked.
The middle wheel also has two spring loaded ball bearings to lock the middle wheel to the outside wheel.
The notch in the middle wheel will be under one of the numbers or letters on the outside wheel, and that number or letter will be the number that must be dialed in to open the lock.
When the middle wheel is locked to the outside wheel the two spring loaded ball bearings in the middle wheel press into notches on the outside wheel.
In the following photo the outside black wheel and the middle white wheel are assembled together.
On the inside of the middle wheel to the right you can see the notch, which is used to lock the lock.
In the following photo the middle wheel is show with the outside wheel. On the top of the middle wheel you can see the ball bearing which is used to lock the middle and outside wheels together.
That ball bearing locks with one of the notches on the inside of the outside wheel.
The inside wheel
A third inside wheel causes these 2 spring loaded ball bearings in the middle wheel to be pressed into notches on the outside wheel. This keeps the combination from changing.
To change the locks combination the bars in the inside wheel can be moved which releases the ball bearings that lock the middle wheel to the outside wheel.
When the ball bearings are released the combination can be changed.
After the combination is change the bars in the inside wheel can be moved back to their original position which will again prevent the combination from being changed.
Each of these inside wheels has two little bars in it that can be moved.
These bars either press against the spring loaded ball bearings which keep the middle wheel locked to the outside wheel preventing the combination from changing.
Or when you want to change the combination of the lock lock the inside two little bars are moved slightly allowing the spring loaded ball bearings to back off which allows the outside wheel to move in relationship to the middle wheel and thus allows you to move the notch in the middle wheel to a new position on the outside of the wheel, which changes the combination of the lock.
Last I don't think the inside wheels move. I could be wrong on this because I am just now analyzing how the lock works.
Bars in the inside wheel
The bars in the inside wheels are used to change the locks combination.There is a dial that twists on the end of the lock. Normally that dial is turned inside and it pushes on the two bars in each inside wheels.
The two bars on the inside wheels keep the spring loaded ball bearings from moving which keeps the combination from changing.
When you want to change the locks combination you open the lock, then turn the dial 90 degrees.
This allows the two bars in each of the inside wheels to back off.
When the bars are backed off this allows the ball bearings that lock the middle wheel to the outside wheel to move around and thus the locks combination can be changed.
Locking mechanism
These are the two parts to the locking mechanism.The inner rod slides into the outside pipe.
The following photo is the inner rod which I think is also called a hasp.
The following photo is the outside tube, which the inner rod or hasp slides into.
The last photo is the outside tube with the inner rod slide inside it. I believe the inner rod is also called a hasp.
