What’s the difference between lane filtering and lane splitting — and which one is legal?

DENVER (KDVR) — Lane splitting and lane filtering — they sound similar, and while they do involve some of the same mechanics, one will soon be legal in Colorado and one will remain illegal.

It’s one of the legislative measures signed into law by Gov. Jared Polis this year: Motorcycle riders, come Aug. 7, will be allowed to lane filter. That means if the traffic moving in the same direction as the motorcycle is completely stopped, the motorcyclist can pass vehicles on the left in the same lane while going 15 mph or less.

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Lane splitting, where a rider passes a moving car in the same direction, will remain illegal. According to the Colorado State Patrol, lane splitting typically involves riding a motorcycle down the painted line dividing the lanes on either side of the roadway.

“The first thing Coloradoans need to understand is that there is a seemingly small but important difference between lane filtering and lane splitting,” said Col. Matthew C. Packard, chief of the Colorado State Patrol, in a release.

When are Colorado motorcyclists allowed to lane filter?

Motorcycle riders can sometimes seem to operate under different rules than a standard four-wheeled vehicle, but largely all motorists are expected to follow all the same rules of the road.

“It’s up to the rider to assess each situation and determine if the conditions are safe and legal to filter – it’s an option, not a requirement to filter,” said Packard. “It is also the responsibility of every motorist to share the road. Drive with etiquette and with the law in mind. Respecting each other and driving without distractions will make all of our commutes faster and safer.”

Lane filtering is legal, but lane splitting is not. This Colorado State Patrol graphic shows how to properly lane split.
Lane filtering is legal, but lane splitting is not. This Colorado State Patrol graphic shows how to properly lane split.

The maneuver is being introduced because it’s been found to be safer for motorcyclists than stopping with other vehicles, as shown in several studies cited in the new Colorado law.

Here are the five rules for lane filtering:

  1. The vehicles a rider wants to pass are completely stopped

  2. The lane is wide enough to fit the vehicle and motorcycle while passing

  3. The motorcycle is traveling at a speed of 15 mph or less

  4. The rider can control the motorcycle safely

  5. The rider must pass on the left without entering oncoming traffic

CSP said it will most likely occur at stop lights or in gridlocked traffic. The law allows riders to navigate toward the front of the line and avoid being sandwiched between two vehicles. It’s also only legal for two-wheeled motorcycles — larger rides, like a trike motorcycle, will be restricted from lane filtering.

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CSP noted that it can take a while for the vast motoring public to catch up with changing road rules. Lane filtering is also not new. Motorcyclists were already allowed to use the maneuver in states like Arizona, Montana, California, Hawaii and Utah.

California, according to CSP, is the only state that allows lane splitting.

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