Touring Tip: Motorcycle Performance Metrics

Jul 10, 2015 View Comments by

Touring Tip: Motorcycle Performance MetricsPart 2: Which Performance Parameters are Important for Touring Motorcycles? – 

You can check out Part 1 here.

My trusty 2006 Kawasaki KLR 650, which had around 43 brake horsepower and 38 lb-ft of torque, was generally an adequate (if not very exciting) all-around touring bike, at least if I was riding solo. After adding a passenger and luggage, though, the KLR just didn’t have sufficient power for quickly overtaking slower traffic on the highway. The weak OEM suspension produced a significantly under-sprung motorcycle, which required an aftermarket upgrade for any serious touring duty. And the electrics on the older KLRs weren’t sufficiently powerful to accommodate running lights, heated grips, and other electrical add-ons that many touring riders have come to expect. Fortunately, most new bikes do generate sufficient electrical power for today’s touring accessories.

Last month our discussion focused on gaining a better understanding of engine horsepower and torque. This month we review both the quantitative and qualitative factors for evaluating the suitability of a motorcycle for comfortable touring duty.

Quantitative Factors

Power Delivery Profile: Power delivery over the full RPM range results in a curve for both horsepower and torque. It’s more important to evaluate the power curves than the maximum horsepower and torque figures published. A good profile for a touring bike is one that reaches its maximum torque at a fairly low RPM and then remains mostly flat thereafter. An engine with a strong mid-range horsepower curve is much better for touring than one with a steep peak that tops out near redline. When comparing bikes, rear wheel measurements are more meaningful than those calculated at the crankshaft.

Power to Weight Ratio: The two most commonly quoted motorcycle weights are wet weight, which includes a full tank of gas and all fluids, and dry weight, which is calculated in the absence of all gas and other fluids. Going strictly by an analysis of dry weight doesn’t account for weight differences resulting from differing sizes of fuel tanks. Although wet weight is more realistic than dry weight, it obviously doesn’t include the rider, passenger, and luggage.

A bike’s Gross Vehicle Weight Rating (“GVWR”) is an important metric for touring motorcycles, because GVWR minus Wet Weight tells riders how much additional carrying weight their bike can safely accommodate. While GVWR is usually available in a bike’s owners manual, it’s often not published for consumers in bike reviews and may require some effort to find.

Nevertheless, a power to weight ratio, calculated using wet weight divided by maximum rear wheel horsepower and/or torque, is an effective metric in it’s own right and for comparing different bikes. For example, let’s take a 900-pound bike divided by maximum rear wheel horsepower of 100. The resulting ratio is saying that each nine pounds of weight is being powered by one horsepower, a ratio of nine to one. A ratio greater than say 12 or 13 to one may indicate insufficient horsepower for touring.

Luggage Capacity: Lockable luggage is very beneficial on touring bikes. Luggage capacity is usually quoted either by its height, width, and depth dimensions (the most frequently used method for soft luggage) or by its internal volume in liters. My experience, however, is that most perceived luggage capacity inadequacies can be solved with an efficient, priority-driven packing strategy—don’t take more than what is really needed.

Range: The maximum number of miles between refueling stops, often referred to as “range,” is determined by multiplying MPG by gallons of fuel tank capacity. Since a fully loaded touring bike with a passenger probably won’t achieve the MPG specified by the manufacturer, some allowance should be made for that in calculating range. A good range for a touring bike is 200 miles or more.

Reliability: Breakdowns while on tour are definitely no fun to deal with and may pose physical risks to riders especially in remote areas. A recently published Consumer Reports survey reported failure rates for many of the major brands. Although reliability can vary across a manufacturer’s various models, selecting a motorcycle brand with a better-than-average reliability track record can help stack the odds against a breakdown in the rider’s favor.

Important Qualitative Factors

Fuel Delivery: Fortunately, most new touring bikes are fuel injected, which eliminates the need to re-jet carburetors when touring at significantly different altitudes. When fuel injection first became available on motorcycles, though, some bikes had a noticeably jerky throttle response. A test ride to evaluate throttle response smoothness is a good idea before committing to purchase any bike.

Safety: In my book, the safety benefits offered by modern anti-lock brake and traction control systems, versus their incremental cost, make them almost a must have on any new bike considered for purchase.

Ergonomics and Comfort: There are several factors that determine a touring mount’s comfort level for daylong riding on multi-day trips. Seat height cuts both ways: folks with shorter inseams will want lower seats and those with longer inseams probably will be more comfortable on higher seats with more room to stretch their legs. Motorcycle seat comfort is a frequently overlooked design consideration by manufacturers. A seat that feels comfortable in the showroom, or even on a short test ride, may be agonizing after several hours of riding. Consequently, custom motorcycle seats have become a significant aftermarket business.

The same can be said for aftermarket windscreens, which often provide riders with more effective wind management capabilities. And many other comfort options are now available on touring bikes, including: heated grips, heated seats, power outlets for heated gear, GPS, built-in communication networks, and much more. One just has to decide what they really need for a comfortable touring experience versus the incremental price.

Handling: An area sometimes short-changed by manufacturers is the bike’s suspension. Heavily loaded touring bikes need a suspension that’s not under-sprung and will be up to the demands placed on it. If your fully loaded touring mount dives under hard braking, bottoms out on rough pavement, or wallows in curves, then a better suspension is needed, which quite likely will be available in the aftermarket.

Although some of a touring motorcycle’s qualitative performance factors can be upgraded directly from the factory, others may require a virtual or actual trip into the aftermarket.

Last, but certainly not the least important factor for evaluating a touring bike, is the personal pride aesthetic. This is easily evaluated by asking one simple question: Will the rider, after dismounting, cast an appreciative gaze back at his or her motorcycle? A bike can have top-notch performance parameters, but it also has to make us feel good about owning it!

 

Want to receive free Touring Tips, reviews, deals and contests, and additional content? Sign up for your free newsletter now!

Tags: , , , , , , , Categories: Touring & Safety Tips