Randybb

Brought in my back wheel that was noticeably out of true, when I picked it up, they said they weren't able to true it radially, and there are still a couple noticeable jumps on the rim. My question is, are they just not so skilled, or is it actually impossible to true? New wheel time? (This is a 700c)

It's fine for road riding but on rollers I can feel the bumps.

fietsbob

My Guess... Damaged Rim got an Impact Flat spot .. they trued it to run between the brake pads ,

start out rebuild with a New rim, that's round.. maybe build a Trainer Only wheel, so It wont see Road Hazards..

Aside..
I've seen a Crude technique of Slamming the rim from the inside Out .. having a solid Post sticking out horizontally,
that fits between the spokes , and those spokes in that sector loosened ..

so the equal Force to the damage, can Bang the rim back out.

but mostly done on Cheap steel wheels not double wall alloy Nice ones ..

Airburst

At the end of the day if you've bent the rim itself, the only way to get it true is to unbalance the spoke tensions. Assuming the rim was perfectly straight and round beforehand, all the spoke tensions on each side of the wheel will be uniform when the wheel's at rest. That's a good situation - it ensures that the load's carried equally by all the spokes. If you start unbalancing tensions, the spokes which are tighter will take more of the force and therefore are more prone to failure. Therefore there's only so much bend that a bike shop can remove before spokes are either slack (and doing no good for the wheel's strength as a whole - they might as well be removed) or too tight and taking too much force.

Homebrew01

Yes, some rim damage can not be fixed.
At some point just the rim can be replaced if needed.
Keep riding it on the road if you don't feel the bumps. Check spoke tension every now & then to make sure they don't loosen up.

FBinNY 

I'm sorry but I have to disagree.

Any aluminum that is not bent so sharply as to have a crease or fracture can be aligned to near perfect, but it may take special measures. The spokes alone can only handle gentle curves or flexes, otherwise the resistance of the rim would call for greater than acceptable differences in spoke tensions. But more serious bends and warps can be pulled closer to true by brute force before the spoke work is done, then aligned as would a new build.

It does take extra work, and some basic hand skills, but anyone who's had to do emergency field repairs on crashed bikes probably has stories of bending wheels back to shape in sewer grates, or pushing out low spots with their feet.

Problem is that too many mechanics lack the depth of knowledge and experience to do any "heroic" repairs these days.

Can a wheel with a bent rim be made perfect again, probably not? But it can be gotten very close with skill and patience, and it doesn't take that long. IMO the standard should be whether it can be trued to work within the brakes and with hops less than you can feel. A skilled mechanic can make an assessment before starting, and either tell you the limits that he expects to achieve, or tell you that the best possible is poor enough that a total rebuild is a better option.

dabac

I do a variation of that, but I use a wooden cradle and c-clamps to pull out low spots. Has worked well so far. But then I've only done low-profile rims yet - but double Wall alloys. Did a tubular that was outright scary. The inside face of the rim was so soft, I had to make a rather elaborate padded "shoe" for the clamp to push against not to dent it when I tightened the clamp.

FBinNY 

Next time you have a light tubular, try it my way. Slacken the spokes in the area as you normally would, take off your shoe, then hold the rim at 10 and 2 while you push it out with you foot.

For rims a bit stronger than you are, you can brace the axle, as in a truing stand, and use a wide nylon web strap like the kind used for lifting or towing and an improvised lever to pull the local area down.

dabac

If I ever get the chance, I will. But light tubulars doesn't cross my path very often.

I think it's a good illustration about how important details are. Rims are not created equal.
First time I tried pushing out a low spot I'd been inspired by a guy who'd poked a broom handle through the wheel, rested it against the backs of two kitchen chairs and heaved.
Didin't work at all for me.
In hindsight I can theorize about him either being a Sumo, or been working on a very flimsy rim.
Then and there though, all the evidence told me was to discard that method.
So I went to c-clamps and cradle, which worked fine.
And according to "don't fix what ain't broke" I haven't had the incentive to try something else yet.
I can afford the minutes it takes to rig up the c-clamps.

Although taking off a shoe would indeed be faster.

Don't think I have a trueing stand sturdy enough for that kind of use. Been thinking about building a monster of a stand, but haven't figured out enough details about it yet. How to be able to clamp any kind of axle for instance. Fat bike compatible. Ability to unload spokes in high tension, low-count wheels.....

Not saying it is required, but somehow I like the cradle method as it isolates the part I'm trying to influence from the rest of the rim rather well. Whatever risk there is of collateral damage to the rest of the wheel seems to be reduced by using an external brace instead of the spokes.
Also, I've seen a car rim repair guy do it that way - with the help of some hydraulics instead of c-clamps though.

dabac

Re-bending rims, or pre-trueing or whatever the process might be called is often entirely doable.
Apart from wrinkles or cracks, the only immediate show stopper I've come across are bends near the joint of a pinned rim.
Then, the rim is prone to coming apart at the joint rather than bending back.
But for bad lateral bends I find it very challenging to do it at anything approaching a commercially viable speed and chargeable result.

Although there are certainly plenty of insufficiently skilled bike mechanics around, I'd blame the commercial constraints rather than lack of skill first.

Maybe if the customer is a MTB-er who does fairly rough trail riding, and uses disc brakes. Limited wheel life anyhow, and the rough surface hide plenty of wheel imperfections.

Sure, one can use a known straight/flat rim as a reference to help spot where to brace and where to bend, but the amount of counter bending needed to end up with a straight/flat rim often interferes with the remaining spokes.
And it seems to me that spokes left in can hide/mask bends even if the whole wheel is detensioned to the point of rattling.

I get better results and less frustration if I unlace and straighten the naked rim as opposed to working on the built up wheel.

So although I might get an almost-new result, I also end up spending about as much time on it as a scratch build would take.

Trakhak

A shop I worked in in the mid-'70s had an Overland Rim-True Straightener, which was designed to be used with the tire and tube installed and inflated.

As suggested by dabac above, though, if the use of that crude tool didn't miraculously return the rim to acceptable straightness after the first try, you were likely to spend way too much time in subsequent attempts trying (and failing) to get the rim straight enough (i.e., to the point where pulsing while braking disappeared).

noglider 

But can it be done cost-effectively and profitably by a bike shop? For some, yes, for others, no. Some shops don't know how to do it. Some know how but can't do it quickly enough for it to be profitable. Some don't want to explain to the customer what is involved.

FBinNY 

My point wasn't that it could be done. It was that the shop mechanic should be able to appraise what will be needed and tell the client what can be done and at what cost before taking and starting the job. I've often looked at a wheel and told someone, that for $XX I could get it decent, but it may pulse when braking, or thump every revolution, or even that the brake adjustment will have little latitude. To get it better would be pricier, and maybe not worth it compared to replacing the rim.

There's nothing wrong with a get it as good as possible without heroics job, but properly assessing it let's the customer make an informed decision before spending his dough and ending up dissatisfied.

Bandera

That's the subtle art of properly taking in a service job: setting expectations for the outcome of work, accurately estimating time for the mechanic and cost for the customer.
The job ticket should reflect this: "Touch-Up" vs. "True".
If heroic efforts are required the job ticket should reflect such in instructions, cost estimate and even assign the job to a lead mechanic.

The Front End estimator's work is crucial to the satisfaction of customers, scheduling of resources and profitability of the service operation.

-Bandera

FBinNY 

Yes, and in some cases where a better assessment may be needed, the service writer should bring in the mechanic who'll actually do the work for a tighter estimate.

BTW- rereading the OP, I might add, that fine for the road, but a bumpy on rollers isn't actually that bad for an old road wheel. Possibly if informed that the OP intended to ride rollers, the mechanic might have warned him.

headloss 

Of course, with every movement, the metal stretches a bit and is relatively thinner and malformed. You can never totally remove such damage short of cutting it out and welding in a patch. If OP wants better roundness, it's new rim time. Not to say it can't be made truer to an extent, but damage is damage (assuming there is damage).

Captlink

I did not read anything about the OP's rim being damaged.Its always been my policy to notify a customer if my work would be less than perfect for reasons beyond my control.It appears that he was expecting a 100% job and did not get it.Can't this damage be detected before the work is done and a bill incurred.