How to identify if a frame has a durable paint job?

Question

Context

I currently have a Merida Speeder 200 which I use as my everyday bike with a chain lock (mandated by the insurance). When (un)locking, the chain may sway around and hit the frame, chipping of small pieces of the colour paint layer (the white base layer becomes visible).

In the past I had a second hand bike with a Raleigh Ace 257 frame, which was used under similar circumstances, but never had a chip of paint fly off.

This might be coincidental, but I thought this might have something to do with the paintjob quality or method.

Question

When looking to buy a bike (both new and second hand), what markers help me identify a durable paintjob that can withstand urban use?

What I've looked into

• Based on this related question it appears that price or overall quality is a marker. However, the Merida was well over 7 times as expensive as the second hand Raleigh and has higher quality components.
• To protect the paintjob the general advice is to use clear protective decals. I have those on areas that are subject to wear (chainstay, where the cables rub the frame), but it's hard to predict where the chain lock will hit next and where I would need to stick a decal.
• My chain lock is in a fabric sleeve over the whole length and I've used mouldable silicon glue to create bumpers around the remaining exposed links. Still, the chain sometimes hits the frame in such a way that paint chips off.

Answer 1

The ultimate marker of how durable a paint finish is is to see how easily it chips :)

You can’t really predict how durable the paint will be. Since paint is a type of coating, it is subject to a vast variety of factors such as the cleanliness of the aluminum, surface roughness, primer choice, painting technique, etc. There isn’t a highly identifiable characteristic you can judge to determine the quality of the entire process.

That said, I’ve found powder coated paint to be more durable. It seems to be less brittle than spray-on paint, chipping less, and is often thicker, so hides scratches better. Since you see white stuff (primer), your frame is sprayed, which may explain the relative ease of chipping.

To protect your paint, purchase a vinyl or (ideally) polyurethane wrap product so you can wrap entire frame tubes, not just using small decals. Some examples include 3M paint protection film, RideWrap, and AMS frame protection. Existing chips can be touched up with matching enamel paint or nail polish. I’ve even had success using artistic acrylic paint for hard-to-match colors, with clear nail polish on top for protection.

Answer 2

I don't think you can tell to look at a paint job whether it will be durable. Perhaps a paint specialist can. There are a lot of different paint techniques and technologies. There are paints that are basically 2-stage epoxies, paints that are basically rubber, as well as powdercoat, enamel, etc.

My most expensive bike has an enamel paint job that is beautiful but not durable.

Answer 3

Paint damage due to locks is a perennial problem. Another option aside from those above is to better cushion your lock. I assume it's the lock itself and attached few chain links that are loose and unprotected, so why not put them in a padded pouch? I would think neoprene wetsuit material would be a good choice and easily found suitable-looking camera lens pouches like this one (example only).