The labor savings with a ride-on vs. a walk-behind can also be substantial. "Typically, a ride-on can cover three to five times as much concrete compared to a walk-behind unit," says Jim Lewis, national product specialist (concrete), Wacker Corp. "Depending on the jobsite conditions and operator proficiency, one ride-on model can replace three to four walk-behind units."

Personal preference also comes into play, says Scott Brening, vice president - operations, Superior Power Trowel Division of Husqvarna. "Some finishers will only use riders no matter what the [job] size," he comments. "Others prefer using walk-behinds because they feel more comfortable with it."

Steve DeGraeve, general superintendent - flatwork, George J. Shaw Construction, Kansas City, Mo., definitely prefers ride-ons over walk-behind models. Despite having roughly 15 walk-behind trowels in the fleet, he intentionally sets up most flatwork jobs to allow use of the ride-on units.

"Over the last four or five years, everything we pour, we try to make big enough so we can put double trowels on it," DeGraeve says. "Walk-behinds might be used 10 percent out of the year for really small stuff. But we try to design everything to go with a ride-on trowel."

George J. Shaw Construction performs a range of concrete work, from schools, hospitals and shopping centers to "big box" stores such as Target and Wal-Mart. Its approximately 25 ride-on units consist of 10-ft. Multiquips, several sizes from Allen Engineering and six new Wacker models.

The 10-ft. ride-ons are usually brought in for any job over 20,000 sq. ft. "For anything under 20,000 sq. ft., we will use the smaller machines - the 8-ft. [ride-ons]," DeGraeve notes. "Then if we get in a small area where we have a lot of stuff to work around, we'll throw in some 36-in. (6-ft.) double trowels."

Baker Concrete takes a similar approach. "When they're doing jobs like a Wal-Mart distribution center and they have a large area, the bigger the better because they will pour 50,000 sq. ft. a day," Anglin points out. "But if they're just doing an 'in and out' place/finish job, they may only be pouring 10,000 sq. ft. at most, so they don't need the big machines."

More power to meet specs
Historically, 10,000 sq. ft. has been viewed as the cutoff between using ride-on vs. walk-behind trowels. However, ride-on models are seeing more and more action on smaller projects. The main reasons are the reduced labor costs and floor profile (F-number) specs.

"One thing that influences [our trowel choice] is the tolerance requirements for how flat and level the slab needs to be," Ahal states. "With the larger equipment, by putting more weight on the floor, you can wait longer before you have to trowel, and therefore you do get a flatter floor."

The higher horsepower generated by ride-on trowels also makes them more conducive to panning. "Everything we pour, we pan it before we start finishing it to get it flat," DeGraeve says. "On probably 85 percent of our jobs, we have a floor profile we have to pass. So our tolerances are real critical. You need a lot more horsepower to get pans going."

More horsepower is also required for certain mix types. "If there are accelerators in the mix, that definitely is an issue," says Allen. "The accelerators make the set time go faster, which is going to require a bigger, more powerful riding trowel in order to keep up."

DeGraeve agrees, noting, "Horsepower does have a lot of difference in the mix. A lot of the mixes we use now, we have to wait until the last minute before we can get to it. We have to let it lay as long as possible."

Weather can be another factor, affecting both the size and number of machines required. "When you're pouring right out in the open, maybe during the day, with sun and wind and different factors, that can cause the concrete to set faster," Ahal points out. "The faster the concrete sets, if you have room to put bigger machines on it, that would be the preference. But I would say it may influence how many you put out there rather than what type."

"Square footage is a huge factor, but weather is also a consideration," Brening adds. "If it is extremely warm or windy, it would be necessary to have more than one machine."

Cost vs. benefits
Even given their advantages, the price difference between a ride-on and a walk-behind trowel may cause some contractors to pause before taking that next step.