PA bike stopping distance law.

[nahtnoj]

"Brakeless bikes are illegal here, as they are everywhere in Pennsylvania, where cyclists must be able to stop a bike moving at 15 mph within 15 feet."

15 feet is less than three bike lengths. 15mph = 22 feet per second. So I have to be able to stop from 15mph in a little over half a second. Anyone think that is possible? Seems like no tire has enough traction to make that happen.

http://www.philly.com/philly/news/homepage/20091124_Ronnie_Polaneczky__Time_to_put_the_brakes _on_brakeless_bikes.html

[Gothard]

I can do that. My bike will stop. I, however, will fly a bit farther over the handlebar....

[nahtnoj]

My thoughts exactly...

I'm trying to find somewhere I can calculate the force that deceleration would produce.

[jpw]

Those numbers put the braking in the 'out of control' zone. Anyway, stopping dead like that isn't really the way to go. Take off the speed and then release the brakes and steer.

If you get 'doored' try aiming for the middle and unclip your shoes asap :-). Alternatively, if you're lucky and the fat driver is quick to exit aim for his or her ample girth and lead with your helmet, bull charge style.

If it's a pedestrian stepping into the road just scream at them and don't change direction - they wil move.

[Kevan]

and probably most of your flight.

That's tough love, brother

[false_Aest]

Applying pump to front spokes should keep the bike within boundary...



http://www.youtube.com/watch?v=KzI-UQ-JsaQ&feature=player_embedded

[SamIAm]

My thoughts exactly...

I'm trying to find somewhere I can calculate the force that deceleration would produce.

You could approximate it with the formula Vf*2 = Vi2+2ax where Vf is final velocity 0 and Vf is 22ft/sec and x is 15 ft. This gives -16 for the acceleration or -1/2g.

[JeffS]

Odd considering there are no such stopping distance laws for cars.

[Louis]

Odd considering there are no such stopping distance laws for cars.

That's because they are allowed to run right over the bikes.

[Tobias]

Odd considering there are no such stopping distance laws for cars.
Years ago at least one state tested cars for stopping power. Not sure if any still do it. The machine used for testing was a monster.

[Tobias]

"Brakeless bikes are illegal here, as they are everywhere in Pennsylvania, where cyclists must be able to stop a bike moving at 15 mph within 15 feet."

15 feet is less than three bike lengths. 15mph = 22 feet per second. So I have to be able to stop from 15mph in a little over half a second. Anyone think that is possible? Seems like no tire has enough traction to make that happen.

I don't think the math works quite that way. You can't estimate time based on initial speed because towards the end of the stop the bike is going very slowly; approaching zero.

The 15 foot requirement seems like a short distance until you consider that stopping distance normally goes up by the square of speed. Stopping from 15 MPH in 15 feet is equal to a car stopping from 30 MPH in 60 feet and from 60 MPH in 240 feet.

As Sam stated, that's only 1/2 g which for a car would suck. Most can pull closer to one g of deceleration in a panic stop. Regarding bike tire traction limitations, 1/2 g isn't all that high either. When we lean a bike enough to scrape a pedal we are in that range (except in lateral acceleration rather than linear).

[rounder]

I thought the Pennsylvania laws sounded harsh, but then checked the Maryland bicycle laws and found this -

21-1207 Lamps and other equipment on bicycles and motor scooters -
(b) Bell - A person may not operate a bicycle or a motor scooter unless it is equipped with a bell or device capable of giving a signal audible for at least 100 feet.
(d) Brake - Every bicycle and motor scooter shall be equipped with a brake that enables its operator to make the wheels skid on dry, level, clean pavement.

I try to be a law abiding citizen, but it looks like i could be busted at any time. Also, I read that the Giro is considering having stages here in 2011. It would be a disaster to the race if the peloton were busted for not sporting bells or other noise emitting devices mounted on their handlebars. Phil Ligett would go crazy.

[rugbysecondrow]

Odd considering there are no such stopping distance laws for cars.
That is because there are federal safety standards for brakes. There are no similar standards for bikes.

[Steve in SLO]

I thought the Pennsylvania laws sounded harsh, but then checked the Maryland bicycle laws and found this -

21-1207 Lamps and other equipment on bicycles and motor scooters -
(b) Bell - A person may not operate a bicycle or a motor scooter unless it is equipped with a bell or device capable of giving a signal audible for at least 100 feet.
(d) Brake - Every bicycle and motor scooter shall be equipped with a brake that enables its operator to make the wheels skid on dry, level, clean pavement.

I try to be a law abiding citizen, but it looks like i could be busted at any time. Also, I read that the Giro is considering having stages here in 2011. It would be a disaster to the race if the peloton were busted for not sporting bells or other noise emitting devices mounted on their handlebars. Phil Ligett would go crazy.

The laws are not so onerous, really:
(b) When in a panic, I can be heard for at least 100 feet.
(d) = legs: skid stops are at the very basis of the "brakeless" fixie movement.

[sg8357]

[snip] I read that the Giro is considering having stages here in 2011. It would be a disaster to the race if the peloton were busted for not sporting bells or other noise emitting devices mounted on their handlebars. Phil Ligett would go crazy.

Not so weird really, check out the British "time trial" bells on ebay,
British law required bells so TT riders had special aluminum weight weenie
bells.