Novice bike mechanic here, but a lifelong bike commuter/green collar grunt. I’ve worked in two bike shops so far, the first being a high-end recreation based shop with an uber-wealthy clientele that bought top-of-the-line carbon machines that they would ride into the fucking ground within a season or two, and the second caters to commuters, lifestylers, and where there is an outdoorsy lean, more x-bike or Crust style stuff. Sure, nothing under capitalism is free from sin, but it still seems to me if you want to go after cycling for being unsustainable, you need to go after the tastes of the wealthy that treat them like toys to shred as opposed to most transport and utility cyclists who, for the most part, are trying to squeeze every mile they can out of their components.

I’m not really convinced that lifecycle carbon emissions are the right measurement for most people in the US (and maybe other developed countries, idk). A car is already a given for most people and is a possible option for every trip you take so the best bike is the bike that replaces the most car trips.

A steel frame bike might release less lifetime ghg than an aluminum frame cargo ebike but it doesn’t take that long for the ebike to catch up if the limitations of the steel frame means choosing the car more often.

napkin math:

(ebike_mfg_ghg - steel_mfg_ghg)/(car_ghg_per_mi - ebike_ghg_per_mi) https://www.wolframalpha.com/input?i=(320kg-35kg)%2F(400g%2Fmi-(41kg%2F15000km))

An aluminum ebike only has to replace 720 miles of car trips that the steel frame wouldn’t to cancel out it’s additional manufacturing emissions. In my experience that really not a crazy number when ebikes:

• expand your radius of effective trips
• reduce the time it takes to make trips
• expands the number of destinations (don’t want to be too sweaty or tired)
• can safely carry much more (grocery or shopping trips)

In the long term with changes to infrastructure or density (or if you already live in NYC or similar) then I think lifetime emissions of bikes starts to become a more effective measure to watch.

Feels like it’s less cut and dry than this article suggests…

It’s weird to me to assume the lifespan of a steel frame vs aluminum when only looking at a perfectly maintained bike. A poorly maintained steel frame rusts out way faster than a poorly maintained aluminum one (does the oxide ever get past the very outer layer?), and I’m not sure anyone bothers recycling the steel bike frame but they do recycle the aluminum one. Also, we’re just looking at manufacturing, but wouldn’t a lighter aluminum bike require fewer calories to move and therefore cause less carbon emissions from the rider over the lifespan as well? Never mind they mention transportation emissions of old vs new but what about new vs new? Would a local aluminum frame be better than a Chinese steel one, especially if considering the other points I’ve raised above?

I guess the point I’m trying to make is maybe now isn’t the time to really be looking at this. Maybe get more people biking, any bike, and if it becomes a major enough form of transportation then we can worry about transitioning people from better to best.