Titanium Stays for Brompton Rack
Aluminum stays in Brompton rear rack/carrier had been a problem for me and other people. Some aftermarket racks look good, but you cannot find out whether they are an improvement over the original rack without a significant investment. The top of the original rack is fine, so the natural question to ask whether simply the stays could be changed into other non-corroding. I first looked into stainless steel stays, but some on-line engineering calculators indicated that for the same physical dimensions stainless steel would bring marginal strength gains and quite a lot of weight penalty. On the other hand titanium would increase the strength quite a bit with a modest weight gain, 8g/stay.
Surprisingly the price per Ti tube, 8mm OD 6mm ID 25cm length, was not that dramatically higher than per stainless or alu tube, $10 including S/H, vs $5. Presumably one could lower the price buying all at once, but I was trying out first with 2 tubes, looking whether this would work at all. To make strong tube ends I even made a jig out of an alu piece, but I am not sure this was really necessary. Now I have a pretty sturdy rear rack on the Brompton. It is the first time since a long time that the folded bike rolls on all 4 roller wheels simultaneously. How the rack will fare in travel remains to be seen. The photos illustrate the progress.
The work was my first serious experience working with Ti as material. It is quite easy in machining and its one funny feature is that it is a bit gooey. It feels at moments like working with a candy bar. When you even edges on the grinder, the sparks are beautiful, like from a Christmas sparkler. It seems that in the future projects, that require modest amounts of material, I will be looking into Ti as option.
New Stays On
New Stays On
Crimping Tube End
Crimped End and Jig
Old and New Stay
Set of Old Alu Stays
Surprisingly the price per Ti tube, 8mm OD 6mm ID 25cm length, was not that dramatically higher than per stainless or alu tube, $10 including S/H, vs $5. Presumably one could lower the price buying all at once, but I was trying out first with 2 tubes, looking whether this would work at all. To make strong tube ends I even made a jig out of an alu piece, but I am not sure this was really necessary. Now I have a pretty sturdy rear rack on the Brompton. It is the first time since a long time that the folded bike rolls on all 4 roller wheels simultaneously. How the rack will fare in travel remains to be seen. The photos illustrate the progress.
The work was my first serious experience working with Ti as material. It is quite easy in machining and its one funny feature is that it is a bit gooey. It feels at moments like working with a candy bar. When you even edges on the grinder, the sparks are beautiful, like from a Christmas sparkler. It seems that in the future projects, that require modest amounts of material, I will be looking into Ti as option.
New Stays On
New Stays On
Crimping Tube End
Crimped End and Jig
Old and New Stay
Set of Old Alu Stays