Renovating Aluminium Frame

struggling

I want to renovate a 5 y-o Scott aluminium MTB frame with loads of flaking paint due to sweat and steel/aluminium interfaces - a mess.

Not bothered about it looking like original - just want it cleaned up. Structurally appears OK.

Should I use paint stripper, or have the whole thing sand-blasted?

Then powder-coated, or just clear lacquered, or ...?

Anybody have any experience of this?

Thanks folks.

dexmax

I'de have it repainted... get the original decals.. and stick it before spraying the top coat.

Frejus

Bead blasing rather than sand blasting would be the answer as it is more caring to the frame tubes. It will also remove any corrosion or marks.

Powder coating is strong and durable.Make sure the powder coater uses an ultraviolet resistant paint as some finishes are ok for indoors and keep their shine but when exposed to the rigors of outdoors go dull and powdery.

Most important is to tape up all threads and head seating surfaces, and put some old screws in the bottle boss threads. to save having to rethread everything.

Saupak

Not that it may matter, . . .

. . . but sand or bead blasting or any other mechanical means of removing paint from a frame automatically negates most manufacturer's warrantees. Zip strip (a.k.a., methylene chloride) can be labor-intensive, but it's fun to watch all the paint bubble and flake off.

If it was me, that's what I'd do, then [Autosol] polish the whole thing.

-Saupak

J-MAT

I can't help you with the paint issue, but be aware of the fact that aluminum fatigues very differently than steel. The engineering term is "yield". When steel yields, it bends and takes a new permanent "set," but doesn't come apart. When aluminum yields, it just breaks clean through.

The aluminum in a beer can is soft. The aluminum in bike frames is very strong, but brittle. Metal fatigue is cumulative; an aluminum frame comes apart or breaks down a little every time you ride it. So does steel, but again steel bends, aluminum breaks. Eventually an aluminum tube or weld will fail catastrophically and break clean through. At speed, this type of failure will result in a very bad crash.

The point is that 5 years is a lot for any frame and especially aluminum. You don't want to be blazing down a hill at 35 mph and have your top tube or downtube separate from the head tube.

Frames and other non-steel alloy components should be retired well in advance of their failure. This means aluminum and titanium seatposts, dropouts on forks, steerer tubes on forks, stems, bars, bottom brackets and especially cranks.

Whatever you do, never use titanium bottom brackets or pedal spindles. As someone who has broken a bottom bracket (Dura-Ace) during competition, I was grateful it was steel and not alloy. The steel yielded slowly, almost in slow motion, and this gradual failure over 1-2 seconds allowed me to thankfully keep it together and not crash. If I were using a ti B.B., I would have crashed hard. I've also cracked Dura-Ace cranks. I continue to use and love Dura-Ace cranks and bottom brackets because they are the srongest!!!

If you are big or strong and especially if you are big and strong, retire frames and components sooner than lighter or weaker riders. Regularly inspect your entire bike (manufacturers suggest before every ride) and especially high stress parts (cranks) and all welds.

Good luck!!!