Wednesday, August 7, 2013

Bad Pavement

The surfaces upon which a cyclist rides in Oslo are pretty rough.  I don't have a handy roughness-o-meter, but its easy enough to notice a crappy ride, and Oslo delivers.

First some background on bicycle infrastructure in Oslo.  There are hardly any bike paths that go even a few km without major interruption.  Bike paths appear and disappear with regularity.  Sometimes on one side of a road, sometimes on the other.  Sometimes a bike path is a line of paint in the main road.  Sometimes a bus/taxi lane doubles as a bike path, sometimes a trolley track.  Sometimes it appears cyclists are intended to ride on sidewalks.  Very often a bike path dumps onto a crosswalk complete with meaningful curb topography.  Last time, in fact make that just about the only time, that I rode along Ring 2 I just felt depressed.  I witnessed everything except the trolley tracks in maybe 4 km.

Oslo also has, in my estimation, a lot of damage to the road surfaces, especially ones that are less trafficked and therefore less important to fix.  Probably the winter does it.

My daily commute includes a bit of cobblestones, a heavy pedestrian zone, large rock paving blocks, bus lanes, trolley tracks, some smaller curbs and lots of broken-up pavement.  They love using blocks of stone sticking up as much as 1cm (I estimate) from the pavement on bike paths around road crossings.

I usually commute on a Nihola.  The standard puncture-resistant tires in front are 20x1.75 (47-406) Schwalbe Marathon Plus, and the tire in back is a 26x1.75" (47-559) version of the same.  The Nihola is of course a cargo trike, and exactly how it rides has a lot do with what is in the box, as well as the tire pressure.  Empty and with hard-pumped tires, hitting a bump (such as those embedded stone blocks) can make the front hop.  Light cargo (and the kid seat) can bounce around quite a bit.  The resulting noise can be a significant irritant, and the ride isn't great for the driver either.  (Its nice to have some form of padding in the bottom of the box.)

A trike generally suffers more from bad pavement than a bike.  The three tires follow their own paths over the bumps, making it hard to avoid everything.  The two front tires can transfer left and right pitches to the rider, and they can also work as a team to transmit bumps, shakes and shivers when they impact dumps simultaneously or nearly simultaneously.  The Nihola designers also made a particular decision that adversely effects its bump-handling: the front tires are set fairly far back.  This is a trade-off that helps the turning radius, stability and the box shape, but also has two significant effects on bump-handling: the wheelbase is fairly short so front-to-back pitching is intensified compared to a typical long cargo bike, and second, some amount of the weight is ahead of the front tires which exaggerates hops.

That all must sound awful.  Its not really awful, its just a Nihola is not really the best machine for traversing crappy pavement.

In response to this, I keep the pressure in the front tires fairly low when in commuting mode.  This is luxurious on the rough sections.  I like it better than my commuting bike (700C 37-622 tires).  They aren't so low that I notice the drag, but I'm not so fast anyway.  Personal preference I guess.  The main drawback of this is that I bump a front rim on an abrupt edge a couple times a week, but this hasn't resulted in a pinch flat yet.  Perhaps the thick rubber anti-puncture layer in the Marathon Pluses is controlling the pinching force.  I also try to pack my bag to handle a bit of bumping, leave the kid seat at home, and I try to remember to go a bit slower around those edges.  (Generally these are short curbs.)

Ambitious owners could change the tires for something slightly fatter, definitely at least 2" would fit front and back.  I would like to try some Big Apple Plus 20x2.15 (55-406) and 26x2.15 (55-559) some day.

Thanks to the one-piece frame, its also possible to unload one front tire on short notice by abruptly steering while leaning the wrong way.  This can be used to hop a tire onto a substantial curb, at some speed and without any harm.  Theoretically this could also be used to "float" a tire over a pothole, but it does disrupt the path of the trike a bit, so I don't do that unless I'm turning anyway.  This also doesn't work as well when loaded, because the center of gravity is generally lowered by cargo.

1 comment:

  1. That was really bad. You cannot enjoy your biking routine if the road you were taking is not in good condition. Anyway, does it have a cemented surface? Usually, cemented pavements are quite difficult to keep smooth in longer periods due to heat and pressure from wear and tear. Asphalted ones, which are versatile and flexible, usually makes for an ideal road to drive in. And you'll probably get more mileage from your wheels on asphalted roads, because they don't get worn out as fast.

    Joan Ross @ Parking Lot Services