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BigUgly 09-26-11 10:33 AM

Flat Spot on rear wheel?
I have encountered something strange on my last two rides. It feels like there may be a flat spot on my rear wheel. It's hard to explain but I can really feel it on the smoother roads. It feels like a thumping on each revelution or maybe a small hesitation. Gets kind of uncomfortable on descents. That being said. The ride before this started I flatted less then a mile from home and changed the tube. Didn't notice it on the last mile as I was crawling back because I was beat. Subsequent rides it has been very noticeable. I even replaced the tube that I put it because I flatted again on my last ride(I guess I didn't get everything out from the first flat). I thought maybe I installed the tube wrong the first time because I did it quickly and just wanted to get home. Has anyone ever experienced anything like this? Thanks.

GMJ 09-26-11 11:18 AM

What kind of tires are you running? I know my dad right now is riding with high-volume/low pressure tires and I always notice that the bottom of his back wheel is "flattened" by his weight.

If you're constantly getting flats, there might be a problem with your tire. Look inside and see if there is anything in there that could potentially puncture it. There's also the possibility that your spokes are puncturing your tube as well.

edit: just realized you've been riding for a while and probably are aware of everything I just said. This is what I get for being a newbie and giving advice.

BigUgly 09-26-11 11:28 AM

Don't sweat it. I may have jinxed myself because I stated to someone this summer that I never get flats. These are the first flats I have had in 3 years. I am running 700x25 and the tire is new as of last fall. I usally run 100 - 105 psi in my tires. It's weird because I have eyed the rim, rolled it over a flat surface without the tire on it and still can't pin point anything.

CACycling 09-26-11 12:20 PM

Is the tire seated properly? I know I had that symptom when I flatted and didn't check to make sure the bead was set all the way around. Check the tire where it meets the rim all around the perimter on both side to see if it dips in. You can also spin the wheel and look at it from the side. You should be able to see if it isn't perfectly round.

pdlamb 09-26-11 03:12 PM

+1 to checking the seating.

If the tire's seated properly, and if you have a bike rack on your car, hang the bike on the rack and check the wheel for true. Grab a Sharpie or a pencil, steady your hand on the frame (or fork) just where the tire meets the rim, and spin the wheel with your other hand. If the wheel jumps up, down, or from side to side, by more than a couple of millimeters while it's spinning, it needs to be trued. Go ahead and check both wheels while it's up there, although the rear wheel seems to lose true way more often than the front on my bikes.

c_m_shooter 09-26-11 06:51 PM

The tire probably isn't seated proberly at the valve stem. let the air out, then push the valve stem in so that it isn't between the tire and rim. I've seen this on narrow road tire before.

BigUgly 09-26-11 07:36 PM

Thanks. Found the spot. Doesn't look like its seated properly. It dips in a little bit at the spot. Never ran into this before when changing tubes but haven't flatted since having this tire installed as the shop last fall while it was in for a tune up. Whew, glad it was something simple like that...

indyfabz 09-27-11 06:55 AM

If you still feel it, turn the bike upside down, spin the wheel and look at the vertical relationship between the rim and the brake pad to make sure you really do not have a flat spot in your rim.

sbentjies 07-20-16 06:38 PM

I'm trying to get a reply on this old thread because it describes my problem. I have what feels like a flat spot and the tire visibly jumps when it goes past that spot. The rim appears to be true so I don't know what to make of it shy of taking it to the shop.

indyfabz 07-21-16 07:26 AM

The rim can be true side to side (i.e. vis-a-vis the brake pads) but you may have a flat spot in the rim. You would be able to see it buy doing what I describe in post #8 of this thread, focusing on the rot the tire. If a portion of the rim looks like it's rising towards the hub, that is a flat spot in the rim. That's a rarer cause than an improperly seated tire. You may also have a bulge in the tire due to damage or a defect.

sbentjies 07-23-16 01:16 PM

Thanks. Turns out it was poorly seated. Reseated it and it's fine. I will still look at the rim though

ChuckD6421 07-26-16 10:01 PM


Originally Posted by sbentjies (Post 18933262)
Thanks. Turns out it was poorly seated. Reseated it and it's fine. I will still look at the rim though

Check the rim as it passes through the brake shoes. No need for a truing stand. I've built many true and durable wheels using only the brakes on the bike. Check that it's true side to side, and up and down (round).
Also check that the valve stem is coming perfectly perpendicular through the rim. Riding a tire soft sometimes can cause the tube to hump up inside the tire making a bunch right at the valve stem.

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