# General Cycling Discussion - Determining best U-lock size

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.

View Full Version : Determining best U-lock size

sqb
05-25-05, 10:58 AM
I've read many good things about the Onguard Bulldog Mini U-lock, so I decided to purchase one. :)

But wait. Let's do the math. I'll follow Sheldon Brown's Lock Strategy (http://www.sheldonbrown.com/lock-strategy.html). My MTB tires are 2.2 inches wide. Add an inch or so for the chainstay, which will be between the tire and whatever I lock to, equals about 3.5 inches of space needed for the bike. (I'll add a cable for the front tire and seat, and to add additional security to slow 'em down. :p ) Now add, oh, two inches for something to lock the bike to, and we're up to 5.5 inches. The Bulldog Mini's dimensions state 5.5 inches total lenth. Subtract 2 inches for the U-lock bars, for 3.5 inches of inside capacity.

Summary: I'm trying to get 5.5 inches of metal and rubber inside 3.5 inches of space. :eek:

Conclusion: I need a longer U-lock.

Considering that one of the popular methods for breaking into U-locks is utilizing the extra space in the U, am I making an error in my locking strategy? :( How are people using the Mini? I haven't physically seen the Mini, so are the dimensions listed inside capacity?

supcom
05-25-05, 11:18 AM
If you can accept the risk, you could use the mini to lock the frame chainstay to the pole and run the cable through both wheels and the saddle. Your rear wheel will not be as protected, but the frame won't be going anywhere. You could also use a second mini lock around the rear wheel and seat tube to provide better security than a cable.

Or, you could use a Krypto NY3000 ULock. Larger size but extremely tough to break.

ajay677
05-25-05, 11:18 AM
You don't need to lock arround the chainstay, just the rear tire and rim, as long as you lock inside the rear triangle. To quote Sheldon Brown:

"People tend to buy the big clunky U-locks because they don't know how to use them properly. A U-lock should go around the rear rim and tire, somewhere inside the rear triangle of the frame. There is no need to loop it around the seat tube as well, because the wheel cannot be pulled through the rear triangle.

Some will object that felons might cut the rear rim and tire to remove the lock. Believe me, this just doesn't happen in the real world. First, this would be a lot of work to steal a frame without a useable rear wheel, the most expensive part of a bike, after the frame. Second, cutting the rear rim is much harder than you might think. Since the rim is under substantial compression due to the tension on the spokes, it would pinch a hacksaw blade tight as soon as it cut partway through. Then there are the wire beads of the tire, also difficult to cut."

So endeth the quote.

pedex
05-25-05, 11:22 AM
the mini is just big enough to lock the head tube to a street sign and still fit in your back pocket

it wont usually be long enough to freelock the front wheel to downtube on a mtb, but it will on a road frame

locking strategy, ya, use a bike thats properly prepared, no quick releases, hex or torx bolts on everything

make bike as unattractive to a thief as possible, shiny decals and new hardware isnt a good idea........even on huffy's

doent matter how you lock up, a decent pair of bolt cutters or canned CO2 and a hammer will defeat almost anything if they really want your bike

sqb
05-25-05, 11:26 AM
I understand that you don't have to lock around the chainstay. However, the rear triangle will be between the tire and the rack, so its size from the tire to the outside of the triangle must be factored into the dimension. Unless you have a rack that bends toward your tire at about the same height as your rear triangle, which is not the case where I will be locking my commuter.

alanbikehouston
05-25-05, 01:09 PM
I can easily put a mini U-lock around the massive rear tire and wheel on my mountain bike and a typical parking meter post. Downtown Houston has thousands of parking meters. Good news for folks who use mini U-locks. Bad news for people who drive downtown.

DON'T put your chainstay up against the locking post. Place the U-lock near the top of the tire, about twenty inches off the ground. Lean the bike about 20 degrees toward the locking post so that your tire is pressing up against the locking post, but there is an inch or two of open space at the chainstays. This method works great with parking meters.

The "rear wheel" locking method is not intended for schoolyard racks. Schoolyard-style racks are NOT designed to secure your bike against crooks. Those racks were designed for no locks, or for cable and chain locks. It is impossible to correctly lock-up a bike to a schoolyard-style rack except at the outside position at each end.

Always use the smallest U-lock that will fit around the rear wheel and a locking post. NEVER put a U-lock around any portion of the frame, including the seat tube. A crook will "lever" on the U-lock, and snap your downtube.

Some bike messengers sometimes need to lock up to telephone poles and light poles that are more than a foot wide. So, they need the Kryptonite Fahgettaboudit. NO U-lock is big enough for those poles.

alanbikehouston
05-25-05, 01:24 PM
...I'll follow Sheldon Brown's Lock Strategy (http://www.sheldonbrown.com/lock-strategy.html). ...How are people using the Mini? I haven't physically seen the Mini, so are the dimensions listed inside capacity?

The photo at Sheldon Browns link shows his bike secured with a Mini lock. So you HAVE "seen" a Mini lock. And, it is around a tire and wheel, and a fat locking post. And, the "Mini" has a lot of unused empty space to spare. Sheldon's lock would easily have fit around a fat tire and wheel on a mountain bike.

In Sheldon's photo, he has placed his mini lock lower than necessary. He has placed the mini lock around the lower half of his wheel. I like to place it near the top of the wheel, at "2 o'clock". That makes it easy to press the tire up tight against the locking post, while leaving some "daylight" between the chainstay and the locking post.

People "tampering" with parking meters? Downtown Houston is littered with cops on horses, cops on bikes, cops on foot. The city police. The sheriff's department. Constables. University of Houston Police. The Metro Police. You can not walk down Main street in Houston between 7 a.m. and 6 p.m. without seeing a cop.

Not ONE of those cops would ever put down a doughnut to stop a crook from stealing a bike off a bike rack. But, if some idiot was silly enough to try to remove the head of a parking meter, they would have a gun at their head, and off to jail on a felony charge. The NEXT "attack" against a parking meter in downtown Houston will be the first.

jhota
05-25-05, 02:13 PM
I can easily put a mini U-lock around the massive rear tire and wheel on my mountain bike and a typical parking meter post. Downtown Houston has thousands of parking meters. Good news for folks who use mini U-locks. Bad news for people who drive downtown.

i never lock to a parking meter - it's relatively easy to knock the head off the meter with a heavy hammer. lift the bike off, toss it and the meter head in the back of a pickup, and remove the lock at your leisure. plus, you get change too.

hell, i used to live in Houston (well, Galveston, actually) - some of the meters there aren't even set in concrete. we pulled a couple right out of the ground with our hands one time (this was in downtown).