It Hurts to Stop

15

Feb

It Hurts to Stop

Anyone who has ridden a bicycle knows, it’s hard to get started from a complete stop.  Some cyclists obidiently stop at all stop signs, lights, etc., others slowly roll through them, keeping just enough momentum to help get them started again, and others simply ignore them all together and just blow through.  We’ve certainly had prior discussion on this blog about the legalities of stopping, but have never discussed the actual reasons why cyclists hate to stop.  A recent article posted on the TimesOnline looks at this exact question.

They start by discussing the relative energy requirements of riding a bike versus walking

… riding a bike at a steady pace takes as much energy as walking at a quarter of that speed. So cycling at 12mph is the same as walking at 3mph. Which explains why most people are as happy to cycle four miles to work as they are to walk one. Cycling at this speed on an uninterrupted four-mile journey, lasting 20 minutes, would result in a total energy expenditure of 90 kilojoules.

and continue onto the meat of the story by saying

Every time a cyclist or pedestrian stops, they lose kinetic energy and have to work harder on starting off to accelerate and restore that kinetic energy. Now — and this is the maths bit — kinetic energy is proportional to mass multiplied by speed squared. This means to reach a steady cycling speed four times that of walking, requires a 16-fold increase in energy (plus about 25% more for the added mass of the bike).

So here it is: the cyclist has to expend about 20 times as much energy as a pedestrian to reach his normal journey speed again. This energy could have carried the cyclist a great deal further had no stop been made. In fact one stop-start is the equivalent to cycling an extra 100 metres while a pedestrian can stop-start and expend no more energy than it takes to walk a couple of steps.

They don’t site any specifics about how these numbers were calculated, so take them with a grain of salt.

7 thoughts on - It Hurts to Stop

  • Alan Barta
    Reply Feb 15, 2009 at 3:21 pm

    If your feet are not clipped in, stopping is not too much bother. If you are, it can be tricky and takes longer, especially toeclips (rat traps, I call them). SPD's (so called clipless) are a little easier than full cleats. Cleats extend your riding range and generally increase safety, since your feet don't slip off pedals on bumps and hills.

    Most recreational bicyclists in Rhode Island AVOID Providence altogether and use clips on their typical jaunts along bike paths and out amidst the countryside where there's hardly any controls because traffic is light. Sure, there it's not onerous to actually stop for an infrequent red light or stop sign, because they only place them where important. Every time you put a cleat to pavement, it wears out a little. I've ground down new cleats on a single ride once walking up steep hills.

    In Providence, unreasonably, there are red lights or stop signs at practically every single intersection. Traffic lights at (mid-block) crosswalks are contradictory. Four-way stops actually increase accidents. More occur at controlled intersections than without. There's a disturbing trend to put lights at every new strip mall entrance, which further aggravates motorists and encourages them to use side streets, many of which in the city now have speed bumps, an additional unnecessary control. One stretch I passed recently had 5 sets of lights in less than 500 feet of road. It's insane overkill; or is it just a cash ploy?

    Such poor traffic engineering and unsafe practice marginalizes bicyclists. Unlike motorists, they can hear and see other traffic, provided they're able and not illegally wearing ear pods. You almost don't want cleats unless you ride a fixie and can do track stands at every intersection. Since some of us ride through city to get to country, we just take extra care rolling through controls. Glocester maintains roads surfaces and sight lines year after year (thank you sincerely) for safety sake instead of hiring a privatized company that speciously serves $75 summons to everyone who parks legally just to raise revenues and unfairly profit. All this does is drive away store patrons and jam court docket with cases that get dismissed.

    Even though nobody's paying any attention to this blog, I reply merely to write about stuff I know. I testify from personal experience. Get yourself a new mayor before it's too late.

  • m. mitchell
    Reply Feb 16, 2009 at 6:18 am

    Cyclists are required by law, R.I. Gen. Laws 31-19-3,et al, to obey traffic control devices, signs and signals, including but not limited to those posted at intesections. It is no more justifiable for a cyclist to fail to stop because of a specious argument about energy conversion than it is for a motorist to fail to stop because fuel is wasted while waiting for a signal to change.

    Urban stop signs, signals, speed bumps, etc. are intended to be traffic calming devices, i.e. they are intended to slow traffic and make motorists more sensitive to local traffic conditions, such as neighborhood children. Although no one likes to wait, we cannot all be the first one through an intesection. Although there are arguably too many traffic control devices, there are also too many motor vehicles as well. That is a reality that is unlikely to change in the foreseeable future, so cyclists must ride responsibly in order to survive and thrive in a dangerous environment.

    Every cyclist should be an advocate for safe, responsible cycling. When cyclists ignore traffic signals and signs they convey a negative image of the cycling community to motor vehicle operators. The reverse is also true; when cyclists obey traffic signals and signs they convey a positive image of cycling.

  • Alan Barta
    Reply Feb 16, 2009 at 10:24 am

    Cities and town are required by law to provide facilities on all roads ≥23 feet wide where bicycling or walking is allowed, which is all roads except interstate highways and some bridges. Until they do, compliance to laws not designed for bicyclists is totally ridiculous. When questioned, Warwick's excuse was they were trying to maintain the "rustic nature" of the city by neglecting to put in sidewalks. They never legally had that option.

    Proper planning and policies would greatly improve the battle between automobiles and bicycles. Cyclists don't want holes dug into road shoulders. Why not put gas and sewer connections into the center of travel lanes? Where gutter slots are provided grates are unnecessary. They appeared as a "solution" when widening roads without changing drainage. ALL these bad/cheap practices visit the cyclist and nobody else.

    Nationwide, some cities tried to unduly restrict cycling, only to be reprimanded and struck down by federal courts. The national ratio of tax spending automotive versus bicycle is roughly 200,000:1. Bush appointee USDOT director Mary Peters says that road funding shouldn't be spent on cycling. To date, there are roughly 4,000 miles of shared streets in RI but just over 40 miles of bikeways.

    Providence ought to post NO PARKING signs everywhere, turn spots into bike/car shared lanes. Horrors? No, take all those closed mills on periphery of city and covert them to huge parking lots, then have frequent short trolley loops between them and downtown. Why don't they? Because they're raking in $10 million a year in parking fines. In other words, they don't give a damn about bicyclists, motorists, walkers, or the public's safety, only what money they can grab and misappropriate. Given general neglect of cycling, police can't be bothered enforcing such laws.

    Because bottom to top, nobody cares, neither do I. You do what you want, and so will I.

  • A.
    Reply Aug 28, 2009 at 6:25 pm

    It's worth looking at the Idaho stop law with regards to this debate. It's been on the books for 25 years and there have been no appreciable changes in accident rates.
    http://bikeportland.org/2009/01/14/idaho-stop-law

    Bike's should be treated differently under traffic law because they are different. Let's start to see some policy that actually addresses how to make streets safer and more efficient for cyclists.

  • Alan Barta
    Reply Aug 29, 2009 at 10:06 am

    ^Good read, rational argument, thanks.

    STOP signs are put in as a kneejerk reaction to accidents on poorly designed roads and placate voting constituents who complain about traffic passing their homes. Nationally, there are 4.4 million motoring accidents per year. Adding controls is clearly INCREASING incidents. Places where they went from green/red control lights to continuous flashing yellow result in fewer accidents, because they introduce doubt, whereas green indicates false CLEAR.

    For cyclists STOP = YIELD; RED = STOP, LOOK, DART ACROSS. A 4-way red is often the only time you can cross many intersections, especially those whose controls only trip for motor vehicles. I ride so slowly I'm practically stopped all the time anyway.

  • Alan Barta
    Reply Sep 12, 2009 at 7:46 pm

    Update: http://www.wired.com/wired/archive/12.12/traffic….

    Landmark case regarding a Drachten, NL intersection where traffic engineers REMOVED all controls to find a net DECREASE in accidents. The "false positive" of a green light or SPEED ZONE message leads to risk taking, while spreading doubt heightens attention.

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