Bumper pitting
 

Anyone got any tips for cleaning and polishing the bumpers. Got a spare one with some pitting, any tips of how these could be removed?

Cooking foil! Scrunch it up shiny side out, dip it in water and rub the chrome bumpers! Amazingly it works, the shiny comes off the foil and fills the pits and being a slightly rough surface, it removes the flakes of rust at the same time.

A gentle polish with Solvol after and (i haven't tried the next step) then a coat of clear lacquer will have it looking like new.

It's a cheap enough method to experiment with to find your best technique and can revive chrome bumpers, tailpipe trims (that's what i tried it on), bike wheels and so on.

Thanks Dave but they’re anodised aluminium so does the old alfoil work on it as well as chrome?

Your bumpers are anodised aluminium? :thinking:

All interesting to read and I don’t know the answer.

Aluminium anodised pre 1980 would have been the absolute F1/NASA type technology. Are you sure?

https://en.wikipedia.org/wiki/Anodizing

https://dorsetaluminium.com/

Why do you say anodising before 1980 would be F1 or NASA technology? It's been around for nearly 100 years and specialist anodising companies have been in existence for many decades, as you will see if you read the history of DAP (Dorset Aluminium) above.

It's a much more common process than you might think and i'm willing to say with some certainty you have anodised aluminium products in your house without even realising it.

Thanks for that. I meant really from a cost perspective. I know that now a days a aluminium framed bike at £250 is good. But from a cost perspective a good aluminium framed bike in the 60s or 70s would be a very expensive piece of kit (if it were even available).

They are anodised aluminium.

In that case i don't know if the foil trick will work. There are options such as stripping the anodise off, polishing to remove the pitting then anodising to replicate the original finish but that's likely to become expensive.

Given that cooking foil is essentially aluminium my idea may still work and probably wouldn't hurt to try it. As the bumper is already pitted, if you can improve it then you've gained a bit, if it doesn't then you haven't really lost anything except a few pence worth of foil and water and a few minutes of your time. If there's a section on the (normally) unseen part of the bumper that is pitted, you could try it there first to see if it's a viable solution for you.

Another option if you have access to or can make your own electroplating area would be to copper plate the bumper, fill the pits with solder then rub it down/file/sand it smooth to fit the contour, copper plate again then nickel plate. This would probably be the most cost effective solution and one of the closest to the original finish - other than that it's probably going to be as i suggested furthr up - have the old anodise stripped, polished and then re-anodised to replicate the original finish. The company i linked to above might well be prepared to do it, i know they would 20 ish years ago but whether they still would is another matter.

That said you may well find someone closer if you do a search.

I think the cost was probably down to the cost of actually making the aluminium bike, back then aluminium welding techniques weren't that widely available. Also the welds weren't that reliable until the 80s :

"Since the late 1930s alloy steels have been used for frame and fork tubes in higher quality machines. By the 1980s aluminum welding techniques had improved to the point that aluminum tube could safely be used in place of steel. Since then aluminum alloy frames and other components have become popular due to their light weight, and most mid-range bikes are now principally aluminum alloy of some kind."

https://en.wikipedia.org/wiki/Bicycle#Frame

I have heard of an older aluminium bike but can't think of the name of it just now. They were in simple terms bolted together but pred-dated the welded aluminium bikes by quite some time.