How Much Radial Runout Is Acceptable?
 

The rear wheel on my wife's 2009 FX 7.3 has about 1.5 mm of radial runout. There is very little lateral runout and no signs of any spoke or wheel damage.

I realize that the Bontrager Nebula wheels are not exactly top shelf, but the bike has only been ridden about 500 miles and all of that has been on paved MUT's.

Is 1.5 mm radial runout too much?

Should I expect the Trek dealer to true the wheel under warranty?

How long have you had the bike? If you purchased it from the LBS and it is still within the service period, I would expect the wheel trued as part of the service plan. As for whether it is service under warranty, you need to read the warranty that came with the bike. But I doubt it, but I don't know since I have never owned a trek and haven't worked for a trek store.

Radial runout isn't as simple as X+ is too much and X- is OK. Is the runout a high spot or a low spot? Is it long and gradual like a big cam, or a fairly local spot that you feel as a pulse when it comes around.

In my experience radial runout doesn't change much over time except for local spots resulting from impact. Bring it the the shop and have them examine and possibly correct the wheel. If you can't feel it as you ride keep an open mind because correcting a cam shaped wheel can me more trouble than it's worth.

BTW- acceptable runout also depends on your tires which aren't perfect either. If the rim is closer to true than the tire any runout is functionally meaningless.

I have a hard time believing that 1.5mm of hop is within factory spec. I'm quite slackerly about radial runout and my wheels mic out to .6mm at the most. It's pretty painless to get a wheel to that point and a bike shop professional should probably be able to do better.

I agree that runout of less than 1mm or less than half that is easily possible and I'd expect it in new handbuilt wheels. My personal standard is that the entire wheel must be as good as the worst spot in the joint (I build mostly light non-welded tubulars).

But the OPs wheel has 500 miles on them and we don't know if he has a low spot, high spot or a cam so I tried to give a qualified answer.

We also don't know for sure that the runout is in the rim and not in the tire as the OP wasn't explicit how he measured it.

+/-1.5mm is not acceptable with any new wheel. You should expect to see +/-0.1mm with a custom wheel, and +/-0.5mm with a machine-built wheel.

ha .5mm for a machine built wheel? yea it can be done but takes more time in the machine. specialized kids bikes wheels(20, 24in) come out great for a machine. i have seen many machine built wheels that look like a roller coaster

Sorry, I should have been more specific.

The 1.5 mm of runout is visible at the OD of the rim (and the tire) and seems to be a high spot of about 60 degrees more or less centered on the valve stem.

Thanks for the help.

You mean a machine-built wheel that has been stress relieved and trued by a human, right? I buy a lottery ticket everytime I see a wheel on a brand new bike that doesn't have to be touched up before the bike is sold. The norm is much greater that +/-0.5mm. Cheap wheels are worse, but I've had to correct mid-range Mavic wheels that have been out of dish by 10mm.

Cheap Wally-World wheels are garbage.

Most bikes with MSRP north of $600 should pass the +/-0.5mm radial run-out. Even the cheap 27" steel wheels sold in the 80s were well within the +/-0.5mm spec. Check out those $400 to $500 road bikes at Costco (Northrock and Diamond Back brands). Their wheels have good tension with very good radial run-out. Lateral run-out can be sloppy due to shipping.

Novice cyclists should check radial run-out without the tire.

Sounds normal for a Trek wheel. They must not do much hand truing on them at the factory. Just about every one I see needs some touching up, usually at the seam and valve stem area. And don't get me started on the wheels on Trek Kids bikes. Some of those look like eggs when they come out of the box.

trek kids bike wheels are awful, terrible

Possibly i have lower standards than everyone
else here, but I'm usually OK with a wheel that
I can ride on a smooth path at speed without
feeling a thump or regular vibration set up by
the hop (radial runout) in the rim.

As others have said, tire can also be a factor.
If your wife notices nothing at speed on a
smooth path, what exactly is the problem
other than aesthetics? At any rate, given
the fact that this much runout in a wheel
can be caused by a single significant bump
in less time than it takes to talk about, I
wouldn't get my hopes up for a warranty
replacement.

But you never know. Somebody ought to
be able to pull this reasonably round in a
stand in ten or fifteen minutes.

Most respectfully,
Mike Larmer

I guess my standards are a little lower
 

In most cases I`d be happy reducing the runout on a wheel to 1mm myself. Yeah, I kow, it would be nice if it was perfect but nothing else is anyway. Most tires have more than that. Apparently the Park Tool website also uses 1mm as a reference too, but that certainly doesn`t make it a bad thing to go for less.

But not everyone has high end bikes either and 1.5mm right out of the box is common on bikes costing less than $600.

I am curious about how some people are measuring runout though. I do ocassionally use a dial gauge for critical work, but have never managed to get a negative reading out of one. How do you end up with a reading like +/-0.5mm anyway? ?y readings are always positive. A zero reading would be no runout. A negative reading? You lost me!

.5 mm is about the worst I usually get.

+/-0.5mm is the same as -.0.0mm to +1.0mm.

That's enough that I wouldn't be comfortable building the bike and letting it go out the door like that. I don't shoot for the stars on bikes in that price range, but it shouldn't be something that catches your eye when you spin your wheel past your brake pad either.

Yeah, just let them know you noticed it and would like it improved upon. That should be all they need to hear to get it handled.