Post-Paint Chainstay Dimpling

I got a call today asking if I could dent a chainstay for a customer. I have yet to see the bike but apparently the spider just barely hits the chainstay in the stand and makes definite contact when he’s out of the saddle.

Before I go down the road of “persuading” metal, I’m going to try a 1-2mm spacer on the DS but the conversation led to me wonder about best practices for dimpling a CS once everything has been assembled and, more importantly, painted.

I think I’d be mostly worried about causing the paint to crack/chip around the dimple and having that damage spread.

I’m flagging this as watching as I just had a buddy ask me to do the same to his Kogswell but for tire clearance.

Its a game of chance. I light press most likely won’t harm the paint but anything substantial is going to compromise the structural integrity of the paint and crack/flake straight away or in time. You could get lucky too and will depending on size of dimple, change of angle at the surface, the quality of the paint aplication and the paint product itself.

Is it painted or powder coated?
I’ve dimpled a powdercoated chainstay on a showbike successfully before, due to the same interference…
This was the contraption used, it was also padded with a thick piece of leather from a heavy apron. Worked fine!


I haven’t seen the frame yet and the customer isn’t sure.

Regardless of what I do, I’m going to make that contraption. It’s probably worth having around just in case.


I’ve done this a few times before when I was a bike mechanic. Usually older bikes already scratched by the chain so it wasn’t really an issue. But I had to dimple the chainstay on new a soma wolverine, so I assume that would be powder coated? I made some wooden forms thinking they would be more gentle on the frame, and I wrapped the area in tape before dimpling. It worked and didn’t crack the paint, but I don’t know if that was luck or skill…
Luckily that area will be covered by the chainring so if you do crack the paint you could hopefully make it look reasonable with touch up paint or nail varnish.

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I’ve done it on wet-painted frames too without any problems, unless they showed up much later and I wasn’t informed (quite possible). Paint thickness might be the most important variable, with thick paint more likely to crack/flake. The ones I did had thin paint. Adhesion is another important variable, which probably depends most on surface prep, maybe paint chemistry too (I’m not a painter). But I’ve indented mass-produced frames with paint that was, let’s just say “rapidly applied” (not fussed over) like a '70s Raleigh and an early-'80s Trek.

I make the vintage style indent (everything about me is vintage) that’s a fairly sharp crease down the middle. I actually believe those are best for fatigue life and I’ll get into it if anyone wants, but that’s off-topic for now. My point is, the sharp indenter should be a worst-case scenario for paint, but it hasn’t caused problems for me.

I made better indenters at two of the shops I worked during my career, but now as a hobbyist I use one I made in a few minutes that frankly needs to be upgraded. I used too cheap a C-clamp (I think the “C” on mine is for China), and the threads are getting grindy. But it makes nice-looking indents, to my old eyes…

Tempted to make one out of a large Vise-Grip, like this one Curtis Odom made for himself, he says it works good.

Curtis Odom chainstay indenter tool

The outer dent in a right-side chainstay is tricky because there’s often a bridge right behind where you want to dent, so you may need something that braces the BB shell instead of the backside of the stay. OK, modern frames are less likely to have a chainstay bridge, showing my age again… At one shop, we had a nicely shaped indenter that just had a 3/8" rod welded to the back of it for striking with a big-ass hammer. We’d clamp two plates to the business end, that went over the top and bottom of the stay to hold it on-center and aligned, and those couldn’t be permanently welded on because different stays need the plates at different spacings, so it was finicky, with a shim stack to get tham at the right width for the stay. But aligning it in 3 dimensions by eye and holding it there while striking with a hammer is not reliable enough.

I have seen some horrible, bad, fugly indents made with hammer’n’punch though, so maybe practice on some dumpster frames before trying it on a customer’s. The ones we did at the aforementioned shop “usually” looked quite good, but I’d advise staying away if you’re risk-averse.

Don’t forget to block the dropout spacing with a dummy axle, and plan on re-aligning the triangle afterward, the stay will move from being indented.


The few dimples I’ve done have been on vintage bikes with wet paint (not powdercoat) and none of them have cracked or chipped. Even with the sharp crease down then middle.

Opposite of denting… in the PDR (paintless dent removal) world, they heat the section to be worked with a heat gun to make the paint more pliable while working the metal.