fast_eddie_72

So I've been fixing up my bike and really enjoying riding it. But it's had this "ka-thunk, ka-thunk" when I ride. Like a lump in the rear tire. I assumed I had twisted the tube or something, so tonight I took it all apart. No, I actually did a fine job putting it on. The stem is seated all the way in the wheel. There's just a visible bump in the tire. And yes, these are very cheap tires from eBay. I thought about just swapping the front and rear tires, but when I looked at the front one, it's exactly the same.

So is that a thing? Tires that just aren't... round? What's a reasonable quality tire that isn't real expensive, but, you know, round?

delbiker1 

Fast Eddie, are you a troll, or is this a real question. You think the wheel might have something to do with it?

aggiegrads

I vote for bead not seated all the way around.

Andrew R Stewart 

If the rim is narrow and if the valve stem base was fully seated in the rim's valley then the sides of the valve base might be keeping the tire's bead from fully seating onto the rim at this point, resulting in a hop. But we don't really know what the OP means by "lump" or "visible bump" since we can't see the wheel. If this is correct then the OP didn't do a "fine job" after all. Andy

79pmooney

On most tires there is a line in the molding just above the rim. If you hold the wheel in your hands and spin it, that line should stay the same distance from the rim as the wheel turns. If that line jumps up or dives below the rim, well there is your issue. (Be sure to check both sides.) Deflate the tire part way, You may be able to massage the tire with your hand to ease a place where the line had dived back up (so the tire bead is properly sitting on the rim shelf). For bulges up, deflate the tire entirely and work the tire around the rim and reinflate. Partially inflate and check the line.

Your issue may be some thing else entirely but this is easy to check (and you want to get it at least close because the high portion popping off the rim means a blown tube that cannot be saved and sometimes tire damage.

Ben

fast_eddie_72

Golly, thanks for the helpful reply.

KCT1986

If the tire has a wire bead, (non-foldable tire), check that the wire bead is bent or kinked. Deflate the tire and push the bead away from the rim and inspect all around the rim. Bend to straighten if needed.

TimothyH

First step is to mark the tire and rim at the high spot with a piece of chalk or sharpie or something similar. Put a line from the tread, down the sidewall and across the rim right at the high spot.

Then take the tire off, rotate it 180° on the rim and reinstall.

If the high spot stays where it is then the problem is with the rim, rim tape or tube. If the high spot moves to the other side of the wheel then the tire is the problem.

Proceed accordingly from there.

Aside from that.... Some can actually feel overlapped or incorrectly installed rim tape. Make sure the rim tape is not folded over or overlapped at the end. Extra thick glue patches can be felt in very thin, supple tires as well. Make sure the tire is inflated properly.

If it is the tires then any decent name brand should do. Vittoria, Schwalbe, Michelin, Continental, etc.

I'd be interested in seeing the eBay ad or knowing the brand and model of the potentially defective tires.


-Tim-

cecu

A photo would really help here...

fast_eddie_72

Thanks everyone. Obviously I'm far from an expert, but I'll look at it tomorrow and try to follow some of the advice here. Thanks!

Or a video I think.

It's not the wheel. The rim looks just fine. But the tire has a high spot followed by a low spot. It's very noticeable. And the pattern looks the same on the front.

I have worked on some bikes before, and have a couple of others here that I'm fixing up for my wife and my son. I put the same brand of tires on my son's bike and don't see the same issue. But there is a difference. His went on like I remember tires going on from my experience many years ago. The ones on my bike are really difficult to get on. Like the wheels are just slightly larger. They're the right size - and the same size that came off of it. And those were almost certainly the original tires that came on the bike. But it takes a lot of effort to get these on.

Anyway, thank you all for the help and I'll see what I can see in the daylight tomorrow.

fast_eddie_72

Thanks Tim,

That's exactly what I did this afternoon. The spot moved with the tire.

cecu

If the tire is hard to put on it might be that the valve is not seating properly in the rim, as suggested by one of the poster already.

Jeff Wills

^^^ If the tire was difficult to mount, check to see that the inner tube is not caught under the tire bead at some point. Also look at the molding line in relation to the rim (per Mooney above). Some tire/rim combinations are just tough to get seated properly on the first or second try.

79pmooney

There are tires and rims that just do not play nice. You might consider different brand tires for that bike, keeping those tires for the bikes they play nice on. I've had tires and rims where getting the beads to sit nicely was near impossible. I've decided life is too short to play those games. Watch rto see if the issues stay with the tire on a different bike. Could just be a tire that flunked GC.

Ben

fast_eddie_72

Maybe this will help. It may very well be that I'm just doing something stupid. Wouldn't be the first time. But thank you for helping me figure out what it is.

fast_eddie_72

Yeah, I just looked for this and I think you're right. In fact, it jumps around quite a bit, but is up considerably where the hump is. Okay. I'll have at it again.

Thank you!

cecu

yeah looks like the tire is not properly sitting on the rim.
see how there is a very thin line about 2mm above the rim, when you watch the wheel spin you can see that the line goes up and down.. where the line goes up (further away from the rim) that's where it's not seating properly in the rim..

might want to try deflating it and making sure that the valve is seating properly

delbiker1 

I apologize to Fast Eddie, my previous reply was not helpful an unnecessary. Before I post, I have to remind myself of the fact that I pose questions that other people probably do not take seriously.

Andrew R Stewart 

Thanks for the vid. What rim is that? It sort of looks like a mid/late 1970s and if so likely doesn't have a hooked edge. Modern tires are designed around said hook edge. Andy

Spoonrobot 

I've had quite a few Grand Bois Hetres from Panaracer that were out of round. I think 3 at this point, out of the 12 I've purchased. These are $60 tires mind you, so it's not just cheaply made tires that can have the issue. I haven't had any issue riding them until the fail but be aware they'll fail early, the rubber at the high spot will wear away first. They presented the same as your video, except for one which was worse and had a radial and horizontal hop as well.

I've yet to have another tire out of round from the many companies I've purchased from so I doubt it's a common occurrence. I'd recommend looking at some cheaper tires from Michelin, WTB or Schwalbe. All have lower-priced lines that are very good.

Brocephus

Looking at the video, the tire does appear to be inconsistent, but I'm also seeing the lip of the rim moving up and down as it rotates. Watch the edge of the rim, relative to the brake pad, there's a lot of variation there.

fast_eddie_72

Yes, it's my late 70s Gitane.

fast_eddie_72

All fixed! Thank you all so much for your help. I had to fiddle with it for 15 or 20 minutes, but the hump is gone.

Yes, the wheel could use some work, and I'll get to that, but it wasn't causing that big hump.

TimothyH

The camera appears to be hand-held and not steady.

Even the brake pad holder moves up and down.

Brocephus

yes, but that's not what's causing what I'm seeing. I just watched again, and the little camera movement there isn't affecting what's clearly an out-of-round rim. The rim edge is bouncing up and down, relative to the brake pad holder. The cameraman would have to keep the camera focussed on the same central point, while moving up and down significantly, to create the illusion of the rim being out, but you can tell from other reference points that wasn't happening. But even so, I wasn't actually thinking that amount play was sufficient to have created that big tire lump, that's just me observing and yammering .