Shared bikes - what makes them robust? We see a proliferation of bike sharing services. Given that most shared bikes are kept outdoors all the time, I wonder what components and designs help to make them robust in order to keep maintenance cost down. 

Here is a number that I found hard to believe, quoted by Horace Dediu on Twitter: Chinese dockless bike sharing companies employ one maintenance worker per 1000 bikes. Western dock systems are close to one per 30.

Addendum: From the Financial Times 26 Dec. 2017 "China bike-sharing apps find UK market tough to crack": According to Mr Seal-Driver, in Cambridge there are 23 operational staff for 450 Ofo bikes. Steve Pyer, UK general manager at Mobike, which does not employ people directly but uses third-party partnerships, says there are about 10-15 people for every 1,000 of its bikes.
Mass - resists denting and damage.  Some are steel, some are aluminium.
Single-speed - a lot of city bikes only have one gear, and those that have more are often euro-IGH (internally geared hub) with 3 speed, no more.  Either way they have 1/8" singlespeed chains.
Chainguards - to keep the chain and pants clean.
Robust lubricants - intended to not wash out.
Tyres - fairly hefty, large, and puncture resistant means fewer flats.


And the big one:


Ongoing maintenance  You may not see it, but the company will do ongoing maint of their bike fleet.  Most of the apps support some kind of "report a problem" so that the fleet staff know where to go to find and fix the bike.  Those that don't have etiquette


Cultural factors will come into it as well - suspect there are more vandalistic yobs in the west than in China.