How to remove dents from rims

[Johan Bornman]

Dear Johan,

 

In 2010 you wrote in this topic:

https://community.bikehub.co.za/topic/81195-dented-tubeless-mtb-wheel-what-to-do/

 

You would take some photos and public them on Tech Q&A how to properly straighten the rim.

 

“I find that hammering the dent out is a far more effective way of getting it almost perfect. However, don't take hammer to rim quite yet, I'll take some photos and show the technique in a separate posting in Tech Q&A. You'll need only three tools and with some understanding and patience anyone can fix a rim. In fact, this skill is a very useful one to have if you ride over rocks. “

 

Last weekend I’ve made a dent in my new Alexrims Evo Super Comp. I would like to fix them. Could you provide me with some hints how to do it?

 

Best regards

 

Kamil

 

Dear Kamil, that thread is now archived and I cannot add to it. But here's the process.

 

1) Distinguish between a bead lip dent and a cavity dent.

 

 

If you look at the photo above, you'll see that the one rim has a longer bead lip than the other. The one with the short lip is the popular Crest rim with what they call Bead Socket Technology. The difference is evident. Unfortunately this short lip doesn't absorb impact as well as the long-lip rims and a dent on a Crest goes into the cavity itself whereas a similar bump on the long-lip rim tends to keep the dent in the lip itself.

 

2) Do NOT attempt to fix a dent with a shifting spanner or vice-grip.

 

The result will be poor and almost certainly leave tool marks where it is unsightly and unwanted. It will also not produce an evenly repaired wall.

 

This photo shows a typical shifting spanner result. The result is localized, uneven and sharp.

 

Remember that aluminium work hardens. At the dent, the material is harder than next to it and trying to work on the dent will produce a bend in the soft section. This is not what you want.

 

 

3) Tools required: a) Ball Peen Hammer, B) Nut whacker (20mm x 200mm Nylon rod c) Flat anvil with 90 degree corners.

 

4) Have a helper hold the rim flat on the anvil. Make sure the plane of the rim is parallel with the anvil's surface. Position the rim so that the end of the lip lines up with the end of the anvil. Not even 1mm back, not even 1mm must hang over.

 

 

5) Position the nut whacker in your non-dominant hand so that it is centred on the bulge (the dent's inside) and as upright as the position allows. Whack it with the hammer.

 

6) Now whack the rest of the dent, always aiming closely before positioning the whacker and whacking it.

7) Resist the temptation to turn the rim over and panelbeating it from the other side. If it is a cavity dent, you may now want to GENTLY whack out the bulge. Use considerably less force than you used on the other side. The cavity is soft If the bulge here is large or, you think you'll hit it more than once, relax the spoke tension in this area first. If you don't do this the rim overcompensates and settles is a new position which will leave a radial dent in the wheel.

 

What results can you expect?

 

1) It won't be cosmetically perfect. Live with it.

2) It will seal perfectly with tubeless installation.

3) On a road rim you may have a slight pulse as you brake. No problem.

Edited July 23, 2013 by Johan Bornman

[Eldron]

Awesome post.

 

I use a block of wood underneath and as a nut whacker.

 

A crude but effective job!

[Johan Bornman]

Awesome post.

 

I use a block of wood underneath and as a nut whacker.

 

A crude but effective job!

Thanks Eldron. Just a comment on the wood. I find that with wood, if I whack too hard, the dent goes the other way. The wood is too flexible - but I understand that it is fine for a once-off. For the nut-whacker, nothing beats it. We can't do without our nut whackers here in the workshop, Again, wood works bit looses too much energy in the blow and then when you give it gas, it splits.

 

The nut whackers are really hard and most of the hammer's energy reaches its target and accurately at that.

[Baaisikilist]

These informative tech posts from JB are awesome. I'd really love to attend a Yellow Saddle workshop. Think I'll suggest that birthday idea to the missus n fam.

[Gas]

Good post!

[Guest Omega Man]

Thanks for this. I must confess to using the bottle opener/shifting spanner method.

[Cameyo]

chapeau bas Johan!

 

Thanks a lot for your post! I'm the unhappy owner of a dented new Alexrim. In my deepest dreams I wouldn't expect that I ask for help among South Africa (I'm from Poland). I will give it a try. However tell me where you get a nut-whacker? I haven't seen such a thing in Poland.

 

Kamil

Edited July 23, 2013 by Cameyo

[Johan Bornman]

chapeau bas Johan!

 

Thanks a lot for your post! I'm the unhappy owner of a dented new Alexrim. In my deepest dreams I wouldn't expect that I ask for help among South Africa (I'm from Poland). I will give it a try. However tell me where you get a nut-whacker? I haven't seen such a thing in Poland.

 

Kamil

 

Hola Kamil my new Polish friend.

 

Where is Poland? Somewhere near Mexico?

 

A nut whacker is a Yellow Saddle invention. It is basically a blunt plastic chisel. The reason for using this rather than a plastic hammer is for accuracy. I make nut whackers from nylon rods which I buy from our local engineering plastics supplier in lengths and then cut them to size on a lathe. They don't saw all that nicely but it will do.

 

I hope you find something suitable. You could also use a hard broomstick cut to size, but it will split, so make two or three before you start the job. Don't use metal.

 

BTW, I'm only joking about Mexico. I know Poland is somewhere near the north pole.

[DR ◣◢]

A lot of whacking going on this thread...

 

But, brilliant post as always Johan.

[Longbarn Killer]

chapeau bas Johan!

 

Thanks a lot for your post! I'm the unhappy owner of a dented new Alexrim. In my deepest dreams I wouldn't expect that I ask for help among South Africa (I'm from Poland). I will give it a try. However tell me where you get a nut-whacker? I haven't seen such a thing in Poland.

 

Kamil

 

Us South Africans are pretty clever people. Afterall, we invented Boerewors.

[nolipoli]

Poland - Isn't that where Santa Claus is?

[Cameyo]

Where is Poland? Somewhere near Mexico?

Poland - Isn't that where Santa Claus is?

 

Poland is a country in Europe, a direct neighbour of Germany. We are not as northern country as Finland, Norway where Santa Claus could live :-)

 

According to my problem. It is solved thanks to Johan's solution. A magic stick, as we called a nut whacker did it's job. Everything is as Johan said. It is not cosmetically perfct, but works tubeless fine and easy (as before). However I used a parquet board instead of an anvil (was too small). These are my tools:

 

http://imageshack.us/scaled/thumb/22/xpzl.jpg

http://imageshack.us/scaled/thumb/812/y15v.jpg

 

BTW

BTW, I'm only joking about Mexico. I know Poland is somewhere near the north pole.

 

Currently there is 35 celsius degress in Poland :-) 10 degrees more than in Johannesburg now :-)

Edited July 28, 2013 by Cameyo

[pastapouch]

Hola Kamil my new Polish friend.

 

Where is Poland? Somewhere near Mexico?

 

A nut whacker is a Yellow Saddle invention. It is basically a blunt plastic chisel. The reason for using this rather than a plastic hammer is for accuracy. I make nut whackers from nylon rods which I buy from our local engineering plastics supplier in lengths and then cut them to size on a lathe. They don't saw all that nicely but it will do.

 

I hope you find something suitable. You could also use a hard broomstick cut to size, but it will split, so make two or three before you start the job. Don't use metal.

 

BTW, I'm only joking about Mexico. I know Poland is somewhere near the north pole.

Poland is the land of BEAUTIFUL woman..IF YOU don't know that...no words

[Cameyo]

Poland is the land of BEAUTIFUL woman..IF YOU don't know that...no words

Absolutely true!