Bicycling is serious business in Palo Alto, where elected leaders often take great pride in the city's new bike bridge, its growing network of bike boulevards and its high rate of students who bike to school.

But on Monday, the City Council defied calls from some of the city's leading bicycle advocates as it voted to prohibit e-bicycles on unpaved paths in the city's open space preserves, including the Baylands. By a 5-2 vote, with council members Julie Lythcott-Haims and Greg Tanaka dissenting, the council also asked staff to explore restrictions on bicycling in sensitive areas in the Arastradero Preserve and the Baylands.

The council vote followed a long debate that placed the city's green values on a collision course. Some argued that the city should be encouraging all kinds of bicycling, including e-bicycles, to meet its sustainability goals. Others suggested that the city steer e-bicycles away from the Baylands, where their speed and noise could interfere with sensitive critters like the salt marsh harvest mouse and the Ridgway's rail.

Members of the city's advisory group, the Pedestrian and Bicycle Advisory Commission (PABAC), were squarely in the former camp. They agreed with the city's plan to prohibit e-bicycles in most preserves but argued that the Baylands should be treated differently because it serves as a connector for regional bike routes and because some of its unpaved paths — including the popular Adobe Creek Loop Trail — are wide enough to accommodate trucks.

"Given that these roads are designed for much heavier vehicles, it is unlikely e-bikes will impact these roads more than trucks," said Penny Ellson, a longtime bike advocate who serves on PABAC. "Please consider the needs of aging people who want to stay active and parents who carry young children on e-bikes, who say that the proposed ban will prevent them from enjoying bicycling in the Baylands."

Resident Mark Shull said he used to ride his bicycle through the open space preserves, all the way to Skyline Boulevard. But at 67 years old, his knees aren't what they were when he was younger, Shull told the council. He now relies on e-bikes to climb hills, and he can't understand why the council is taking aim at imposing new restrictions.

"A lot of us are trying to use e-bikes instead of cars," Shull said. "I think that the city should support that and, yes, people do use some of the trails for commuting for good reason — because there's no alternative."

Lythcott-Haims and Tanaka both supported his position and urged their colleagues to allow more lenient rules. Lythcott-Haims suggested allowing e-bikes at both Arastradero Preserve and the Baylands and setting a speed limit of 10 mph, though her motion to explore that policy failed to advance.

While her colleagues argued that a speed limit on bikes would be nearly impossible to enforce, Lythcott-Haims suggested that education and enforcement would be a more effective approach than an outright ban.

"My feeling is if the fee is high and the park rangers do spot checks, we can deter the worst offenders," Lythcott-Haims said.

Tanaka, an avid cyclist, suggested that e-bikes are a key tool for getting people out of cars and helping the city meet its goal of reducing greenhouse-gas emissions. He said he recently installed a motor on his old bike, which he regularly uses to get to Milpitas. Because a portion of the trail is unpaved, e-bicyclists will have to either switch to cars or take a street route that would add more than 10 miles to their two-way trips.

"By doing this you may be cutting off people who may be biking from Milpitas … or people who are biking from other areas that are to the east of us," Tanaka said. "What we're doing is going to create more traffic in our streets, more parking problems, more greenhouse gas. So I just think we need to think about this carefully."

The policy change was prompted by Assembly Bill 1909, a state law that took effect at the beginning of this year and that established that all classes of e-bikes are now allowed on all trails unless prohibited by a local ordinance. This includes some of the more powerful e-bikes in the Class 3 category, which according to staff can help riders reach speeds of up to 28 mph. Palo Alto has historically allowed e-bikes on paved roads and trails but not on unpaved ones.

To address the new legal landscape, the Parks and Recreation Commission debated the new e-biking policy over a series of meetings last fall, ultimately opting to adopt a broad ban on e-bikes of all classes at open space preserves, including Arastradero Preserve and the Baylands. (The Foothills Natural Preserve already bans bikes of all sorts.)

Commission Chair Jeff Greenfield, who led the effort, said that the discussion inevitably led to "genuine passionate support for competing priorities, like transportation corridors versus enjoyment of nature, community recreation versus habitat and wildlife protection."

"At this point, the benefit of the doubt is given to preserving this true city treasure," Greenfield said, referring to the Baylands.

Most of Tanaka's colleagues didn't buy the argument that the e-bike ban would deter commuting cyclists, particularly after city staff noted that even with the new policies, they will still have the option of taking paved trails from East Palo Alto through Palo Alto and into Mountain View. Greenfield said the idea of keeping a Bay Trail commuter open to e-bike commuters was very important to the commission and said the shortest path on the regional trail remains open to e-bikes.

The council ultimately agreed with his commission's recommendation, which prioritized habitat protection over accommodation for e-bicycles. Matthew Dodder, executive director of the Santa Clara Valley Audubon Society, was part of a group of environmentalist leaders who suggested that having louder and faster bikes in the Baylands could disrupt sensitive habitats. Areas like Byxbee Park and the Mayfield Slough, he said, support a wide range of species, including winter and burrowing owls, many species of hawks, migrant geese and waterfowl.

Many of these species may be "displaced by fast-moving motorized bikes interfering with their foraging and/or breeding cycles," Dodder said.

"These areas want a quieter and more relaxed pace," Dodder said.

Some bike advocates took issue with the idea that e-bikes would disturb wildlife and noted that there haven't been any credible studies that substantiate that claim. Yet this very uncertainty only further encouraged the council to adopt a more conservative direction. Council member Ed Lauing said the lack of information is a good reason to proceed slowly.

"'We shouldn't just say, 'What the heck let's put bikes out there.' I say, 'What the heck, let's just go ahead and have critters out there and people out there and let's do some more study,'" Lauing said.

He and most of his colleagues agreed that the primary function of the Baylands is as a nature preserve and that its habitat should be protected, even if that means forcing bicyclists to take different routes. Lauing noted that bicyclists would still be able to ride on the paved roads in and around the Baylands.

"Sometimes hikers like myself stop and focus on a bird or a snake or a bug and my nose is down in the weeds," Lauing said. "If someone comes through on a big, heavy bike, that will disrupt everything. Maybe the critter runs away; maybe I run away because I'm getting out of the way of the bike. Any bike zooming by disrupts this fundamental reason for being out there for people, quite apart from what it does to the critters."

While they agreed that speed limits may be helpful, council members doubted that they would be enforced. Council member Vicki Veenker and Vice Mayor Greer Stone both suggested that e-bike riders will be tempted to go faster than the current speed limit of 15 mph.

"Those things can really fly," Stone said. "When you let that throttle go, it's a great time. I can't imagine, being out there in the Baylands, anyone would really want to pull back on that. I don't see that as a realistic possibility here."

The speed issue, however, isn't limited to e-bikes. Council member Pat Burt, a longtime cyclist, urged his colleague to support new policies that would apply to all bicycles and that would limit speeds to 10 mph open space areas and restrict bicycle and horse access altogether on sensitive single-track trails in the Arastradero Preserve. Once updated, the regulations could potentially pave the way for allowing Class-1 e-bikes to return to the open space areas.

"I think 20 mph is too fast for any bike that we have in these open space areas," Burt said.