Buell ZTL, Mineral Wealth, Helmet Locks And More! - Answers - MC Garage

Ask The Pro

QAfter seeing the Buell ZTL (Zero Torsional Load) braking system and riding one of their bikes at a demo-day recently, I'm wondering why all the bike manufacturers don't adopt this system. From an engineering standpoint it seems to be the way to go by drastically reducing unsprung weight and simplifying the system. I wasn't able to fully test the benefits since it was a group ride, but I would love to know your opinion on the benefits and drawbacks.Tony LaMatina
Victorville, CA

A Better Brake?Creator of the revolutionary RADD steering/suspension system used on Yamaha's pioneering 1993 GTS1000, James Parker knows his way around a motorcycle chassis better than most.

A "Because it's important to be clear about what's being compared, we'll compare Buell's ZTL to a conventional double-disc system. ZTL has less unsprung weight, and the reduction in wheel weight is mostly near the hub. Some heat will be transferred to the rim and tire through the fasteners, which might be a negative factor in racing applications. However, the rotating mass/inertia of the large-diameter ZTL disc and its fasteners are a negative factor. You'd have to do the math to get an exact rotational comparison with two discs, but that one big disc certainly isn't a large improvement.

"Of more concern is the ZTL caliper. It's been described as being less resistant to flex than conventional calipers, and there is a good reason for this. The 'bridge' of a conventional caliper-the structure connecting the two sides-is longer than the bore area, and the circumference outside the disc diameter is longer than that of the disc swept diameter. In the ZTL system, the opposite situation exists. To make a long bridge-as on the conventional caliper-it's necessary for the ends of the bridge to be further from the bores, which increases the leverage loads on the bridge. That means more flex. A ZTL caliper of equivalent rigidity will be heavier than a conventional caliper, but lighter than two.

"Here's one more potential difficulty: With the ZTL system, one fork leg takes all the braking force. Modern forks with clamped axles and big triple clamps can handle this, but must be considered and designed for.

"There are rumors of a Buell Superbike. Will the ZTL system be adequate? Going to two ZTL discs is not going to be an attractive option because of the large increase in rotating inertia. If a bike with a single ZTL disc could eventually win Superbike races, that would be huge.

"The bottom line? No truly large benefits, but no big problems on the street."
Got a question for answers? Send it to mcmail@primedia.com

Mineral WealthMy KTM 990 Superduke has a Grimeca clutch master cylinder that specifies mineral oil, similar to what I'm used to using for my mountain bike's disc brakes. What's the difference, and can I top it off or replace it with conventional brake fluid?Ned T. Bass
Belle Fourche, SD

We put your question to KTM's Media Relations Manager Tom Moen, who replied, "Most of our bikes come with a Magura master cylinder that specifies mineral oil. They recommend Magura fluid, though you could use fork oil in a pinch. You can't use brake fluid, which will cause swelling and subsequent damage to the seals and O-rings."

Lock It or Lose ItI recently had my Shoei X-Eleven helmet stolen from the helmet lock on my '99 Honda VFR. The thief cut the nylon chin strap of the helmet. This was mid-day in the Bally's parking lot. I've heard of this being done, but it had never happened to me before.

I'm interested in a good metal cable that can be looped around the chin bar and locked into the OEM helmet lock. I know I can lock my new helmet by using my Kryptonite around the chin bar and the wheel, but it's kind of a hassle when I'm just going to the gym. I would like something relatively small and easily portable. Have you seen any heavier-gauge cables designed to be used with the OEM locks?
Walt Cailleteau
Rancho Cucamonga, CA

Donna Tocci, Marketing Manager at Kryptonite, has a firm grip on how to hold on to what's yours. "Most people don't lock their helmet because they aren't gone for long or think that nobody would want it. A simple cable lock is enough to stop the crime of opportunity with helmets and jackets. If you want better protection, a U-lock or small chain would be more secure.

"I'd suggest a cable lock. The Kryptonite Krait or a Krait Combo would work well. It's a 15mm cable and not at all flimsy. The combo means there's no key to lose, but there's a combination to remember. The KryptoChain and Padlock is a small chain that also works with a full-face helmet, and might also lock up a jacket, too. It's also fairly lightweight.

"Run a cable through the chin bar and around the frame or a part of the motor-cycle a thief can't easily remove. Park in a location where there are other vehicles, if you can. The chances are pretty good someone nearby will have less security, or no security. Thieves go for the easiest target every time."