How Do You Test Rim Trueness

Willsmotorcycle

Willsmotorcycle

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Oct 26, 2020
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Location
Makefield Highlands PA
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2016 ST1300P
2024 Miles
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Greetings all, I posted this picture in another thread. Eagle eye @Andrew Shadow noticed what may be a bent spot. I can't feel it or I can feel it... Without a specific device, how would one check if this is bent ?


IMG_5176.jpeg
 
Dial indicator is the best and most accurate. Barring that, you are lucky that it is the rear wheel which makes it easier to spin it in place without lateral movement.

You need a solid stable surface to work from. If you have them, set up two jack stands beside the wheel. Take whatever you have that will not damage the wheel- a hardwood broom handle works well. Place the broom handle across the top of the two jack stands- two stands makes the broom handle more stable. Rotate the wheel while slowly pushing the end of the broom handle closer to the wheel until it touches. If it touches in only one spot, that spot is not in the same plane as the rest of the wheel.

If you don't have jack stands, a bucket or any thing can be used because this is just to give you an idea. To have any meaning you need to know how much run-out there is. The run-out needs to be accurately measured with a dial indicator. It should be measured in both planes. The rim can be bent to the point that it can easily be seen by eye and still be well within Honda's allowable run-out limits. It is quite surprising how much Honda allows.

From what I see in that photo, I highly doubt that it is anywhere near the Honda limit. If you don't feel any vibration or other strange rotation related symptoms, don't worry and go ride.
 
Can use a straw and some wood etc. You basically want to have the straw touch the outer edge of the rim like a dial gauge would.

Spin the wheel and see how much the straw either flexes as the wheel moves towards it, or for the gap if the rim moves away from it.

You can really use anything that will flex and deform if the wheel pushes on it.

Something like this... and you can mount the "straw" to anything.

1694134000833.jpeg
 
Or you might have hit a pothole like I did. Or a fair sized rock. On your way up to the Arctic Ocean. If it is bent (and I also think it looks bent), it looks like it’s bent towards the centre of the wheel, as opposed to being bent away from the tire. That’s what my front looks like. And I can’t tell the bend is there just by riding it, only when you rotate it and watch it spin. Heres what I would do: put the bike on the centre stand, run it in 2nd gear and hold a black sharpie or a stick, anything really, close to the edge of the rim and your bent area will immediately become visible. OR. Put the wheel on your balancer and spin it; you’ll likely be able to see it just watching it.
 
Can you feel it when riding?

Does it hold air?

I would be looking more closely at the wheel as opposed to the bead. I hit a 4" X 4" at 70 mph and knocked a very obvious dinger in the back wheel. It lost about 10 psi immediately. The front bead area went from near vertical to near horizontal for about 7". The center portion, between spokes, had about a 3" split. Went flat immediately. I wore the rear tire out and put another tire on it. No problems.
 
Ron said:
Can you feel it when riding?

Does it hold air?

I would be looking more closely at the wheel as opposed to the bead. I hit a 4" X 4" at 70 mph and knocked a very obvious dinger in the back wheel. It lost about 10 psi immediately. The front bead area went from near vertical to near horizontal for about 7". The center portion, between spokes, had about a 3" split. Went flat immediately. I wore the rear tire out and put another tire on it. No problems.
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No, can't tell it's bent, held air for a while now.
 
If it is bent I am sure that it will not cause any problems, on Uncle Larry's VFR he bent his wheel a lot worse than that in two places and the tire held air and he could not feel it. The tire bead on his looked like it would not stay seated, he road it home after patching three flat tires caused by some sharp objects he ran over. This damage was caused by a road he picked us to ride which turned into a very rough and rocky river bottom. He did send the rim off and had it straightened by a company.
 
for me personally the test is it either holds air properly, or it doesn't. Yours does appear to have a very small bend to it, but nothing I'd be concerned about. However, what's going on with the bead of the tire in that area, it looks like there's a long split in the rubber surface. I'd keep a close eye on that until the tire eventually gets replaced.
 
If it holds air and there is no detectable wheel hop or shimmy I consider it good to go. My RT has a flat spot on the front you can easily see, no gauges needed. No effects when riding or mounting tires for more than 50,000 miles. It was like that when I bought the bike.
 
dwalby said:
for me personally the test is it either holds air properly, or it doesn't. Yours does appear to have a very small bend to it, but nothing I'd be concerned about. However, what's going on with the bead of the tire in that area, it looks like there's a long split in the rubber surface. I'd keep a close eye on that until the tire eventually gets replaced.
Click to expand...

FYI that's a darkside tire so the sidewall on it looks about like it should for a car tire. It appears to be excess rubber from the molding process.
 
Obo said:
Ahh the old stationary pencil test.... where you're left to draw your own conclusions about how sketchy it might be.
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I will be unable to erase that from my mind, although to your point, you are write. I may be trying to hard here.
 
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