Fnaar
Smutmaster General
- Location
- Thumberland
After a bike/pothole interface today. Two flats, and two dented rims 
Rate my rims
- Thread starter Fnaar
- Start date
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flake99please
We all scream for ice cream
- Location
- Edinburgh
I have asked my guide dog, and it can’t see the rims either.
OP
OP
Fnaar
Smutmaster General
- Location
- Thumberland
Sorted :-)
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
Carefully bend back if you've got lots of braking surface left... if not, bin. Bend one way only....
OP
OP
Fnaar
Smutmaster General
- Location
- Thumberland
tbh, I took to bike shop. He reckons they might be OK, will know Tuesday afternoon.
Stompier
Senior Member
It's already been bent one way, unfortunately.
SkipdiverJohn
Deplorable Brexiteer
- Location
- London
It's nothing that an adjustable spanner, a hammer, and some sort of makeshift anvil won't be able to sort out. The back wheel on my hack Pioneer had a bulge in it worse than that after going into a big pothole, and I'm still riding that rim after whacking it with a hammer and straightening the bent bit in the jaws of a vice.
Racing roadkill
Guru
If they’ve taken that much of a whack, there’s all sorts of mischief happened that’s not immediately obvious. It will become obvious if you continue to use them though. Bin them, they’re not safe.
Vantage
Carbon fibre... LMAO!!!
- Location
- Behind everyone else, Bolton
Granted, as they've been bent once already, bending them back will further weaken them but not enough to bin them. Keep an eye on them for future cracking, otherwise I'd consider them perfectly OK. I've done similar.
Concur. I'm no metallurgist but I know enough to know that aluminium that undergoes plastic deformation becomes work-hardened. Work-hardened alu is known to fail catastrophically without warning. I'd not risk it.
I would probably give it a go, laying the rim flat against a surface, then using a piece of wood against the dent to spread the load when hitting it with a hammer.
But ally rims often aren't good for getting out dings like this, its the reason dirt bikes use steel rims.
But ally rims often aren't good for getting out dings like this, its the reason dirt bikes use steel rims.
SkipdiverJohn
Deplorable Brexiteer
- Location
- London
No metal rims are that good for getting dents out of, just that steel has to be bent backwards and forwards more times before it cracks. All dents & bulges require the material to have stretched beyond it's elastic limit, and when you attempt to remove a dent or bulge you are trying to push the stretched metal back where it came from. You can never do this fully, which is why the sensible & pragmatic approach is just to aim to get rid of the worst of it, but don't expect the wheel to regain 100% of it's pre-impact profile - because it won't. Aim for a degree of repair that eliminates the worst deformation that could cause vibration under braking, using the minimum amount of squeezing & hammering you can, run a file over any rough edges and then leave it alone.
Be grateful it wasn't made of carbon fibre. You'd probably have a big chunk of material actually missing from the impact site, and the rims would be bin fodder. With some care, those alloy ones look saveable, although they will need to be watched going forward for signs of metal fatigue. There's no need to be a drama queen every time some part of a bike takes a whack, just be aware that some degradation in the material will have happened, and keep an eye on it for signs that it is getting worse. Not all of us bomb down hills at 40 or 50 mph, and for everyday riding at moderate speeds there's no need to be paranoid.
Yellow Saddle
Guru
- Location
- Loch side.
Infinitely mendable.
However, do NOT take to it with an adjustable spanner as suggested. That will kill the rim. If you position the spanner as suggested, you'll notice that the pushing mandible of the spanner fulcrums against the brake track, just a couple of mills off the edge of the rim. Putting pressure on it now to bend the rim back will put a dent in the rim and create a very uneven 50mm or rim. Don't do it. Further, the temptation is then to try and correct the newly-induced mess and soon you have a train smash of a rim.
Take a deep breath, open a beer. Then take a step-by step approach to it. It may take you a few days to get everything you need together, but it is worth it and deeply satisfying.
You will need.
1) A flat anvil. That means any flat, steel surface strong enough to bang on. A real anvil is too cured. You need a piece of I-bar or such.
2) A hammer. Any hammer will do.
3) A 20mm nylon rod 300mm thick. This can be ordered off e-bay or from engineering plastics supply companies. It is cheap. A broomstick does not work. It is not hard enough and splits with the first blow.
4) A friend with a steady hand.
Method:
Examine the rim and mark, on the inside, the area of the dent. Place the rim with the brake track flat on the anvil and let your helper lift or raise the wheel so that the brake track is absolutely flat and level with the anvil.
Now position your nylon rod (called a rim whacker in our workshop) at the best upright angle allowed by the situation on the dent and bang the rod once only. The first bang will be in the middle of the dent. Now inspect, re-align (helper is instructed to move up or down as you eyeball the flatness at anvil-level). Whack again, this time focusing either side of the centre of the dent.
The whacking is quite complicated in that you have to apply pressure to the rim whacker in two directions before striking it with the hammer. You have to push it towards the hub and, hold it very firmly against the rim. Do not tap tap tap. The rod will then move around. Tell the helper to push towards you and you push back in that direction with the rod before striking.
That's all. Never attempt to re-correct. Besides, this will not be necessary because the flat anvil will prevent an over-corrected situation.
Aluminium work-hardens with bending and by attempting to bend it with some sort of spanner and fulcrum, you will induce a bend into the adjacent soft area, causing a ripple. By hammering directly onto the hardened dent you prevent this and focus the correction where it is needed.
There is ZERO risk of the rim failing on you provided the brake track isn't already worn away.
I've done hundreds of these and 99% were successful.
If the initial pothole impact has induced a bulge into the hollow (spoke-side) of the rim, that too can be corrected but it is a bit more complicated.
Because the rim is in compression from spoke tension, by panelbeating on that side of the rim will cause the rim to relax and shrink towards spoke tension. You first have to loosen the 6 or so spokes adjacent to the bulge before panelbearing it. The method is the same, using a rim whacker, hammer and anvil. If your rim doesn't have a brake track, you have to be extra careful in holding it in the right position on the anvil.
This is NOT a one-man job.
Drink a beer afterwards and go for a ride.
Flat anvil, nylon rod and ball-peen hammer.
Position the wacker nicely in the middle of the dent. You will have to have the rim against the edge of the anvil so that the wacker's lower edge can be positioned lower than the anvil level.
The rim is held with the brake track flat on the anvil and the helper will be holding it steady and pushing towards you. You will counter the push with the wacker.
This is the damage done by someone who attempted to bend it with a shifting spanner. Yet, we still managed to get this brake track flat again and save the rim. If the rim itself made contact with tarmac, there will be rough edges what will interfere with the brake blocks. File, sand and hone them out.
The wacker has to hang over the edge of the anvil in order to reach inside properly. That's why you need an anvil with a flat top and perpendicular edge. A standard anvil does not have such a surface.
However, do NOT take to it with an adjustable spanner as suggested. That will kill the rim. If you position the spanner as suggested, you'll notice that the pushing mandible of the spanner fulcrums against the brake track, just a couple of mills off the edge of the rim. Putting pressure on it now to bend the rim back will put a dent in the rim and create a very uneven 50mm or rim. Don't do it. Further, the temptation is then to try and correct the newly-induced mess and soon you have a train smash of a rim.
Take a deep breath, open a beer. Then take a step-by step approach to it. It may take you a few days to get everything you need together, but it is worth it and deeply satisfying.
You will need.
1) A flat anvil. That means any flat, steel surface strong enough to bang on. A real anvil is too cured. You need a piece of I-bar or such.
2) A hammer. Any hammer will do.
3) A 20mm nylon rod 300mm thick. This can be ordered off e-bay or from engineering plastics supply companies. It is cheap. A broomstick does not work. It is not hard enough and splits with the first blow.
4) A friend with a steady hand.
Method:
Examine the rim and mark, on the inside, the area of the dent. Place the rim with the brake track flat on the anvil and let your helper lift or raise the wheel so that the brake track is absolutely flat and level with the anvil.
Now position your nylon rod (called a rim whacker in our workshop) at the best upright angle allowed by the situation on the dent and bang the rod once only. The first bang will be in the middle of the dent. Now inspect, re-align (helper is instructed to move up or down as you eyeball the flatness at anvil-level). Whack again, this time focusing either side of the centre of the dent.
The whacking is quite complicated in that you have to apply pressure to the rim whacker in two directions before striking it with the hammer. You have to push it towards the hub and, hold it very firmly against the rim. Do not tap tap tap. The rod will then move around. Tell the helper to push towards you and you push back in that direction with the rod before striking.
That's all. Never attempt to re-correct. Besides, this will not be necessary because the flat anvil will prevent an over-corrected situation.
Aluminium work-hardens with bending and by attempting to bend it with some sort of spanner and fulcrum, you will induce a bend into the adjacent soft area, causing a ripple. By hammering directly onto the hardened dent you prevent this and focus the correction where it is needed.
There is ZERO risk of the rim failing on you provided the brake track isn't already worn away.
I've done hundreds of these and 99% were successful.
If the initial pothole impact has induced a bulge into the hollow (spoke-side) of the rim, that too can be corrected but it is a bit more complicated.
Because the rim is in compression from spoke tension, by panelbeating on that side of the rim will cause the rim to relax and shrink towards spoke tension. You first have to loosen the 6 or so spokes adjacent to the bulge before panelbearing it. The method is the same, using a rim whacker, hammer and anvil. If your rim doesn't have a brake track, you have to be extra careful in holding it in the right position on the anvil.
This is NOT a one-man job.
Drink a beer afterwards and go for a ride.
Flat anvil, nylon rod and ball-peen hammer.
Position the wacker nicely in the middle of the dent. You will have to have the rim against the edge of the anvil so that the wacker's lower edge can be positioned lower than the anvil level.
The rim is held with the brake track flat on the anvil and the helper will be holding it steady and pushing towards you. You will counter the push with the wacker.
This is the damage done by someone who attempted to bend it with a shifting spanner. Yet, we still managed to get this brake track flat again and save the rim. If the rim itself made contact with tarmac, there will be rough edges what will interfere with the brake blocks. File, sand and hone them out.
The wacker has to hang over the edge of the anvil in order to reach inside properly. That's why you need an anvil with a flat top and perpendicular edge. A standard anvil does not have such a surface.
