bikeme

I noticed a pogoing from a rear wheel while riding (on my hardtail mtb). It's like an elliptical feeling. Can that be trued out? It also has the typical side to side wobble which I know can be eliminated. Thanks.

fietsbob

Bike shop can see and fix things..

elliptical feeling but not seeing out of round?

take the bike in for service

FBinNY 

Short answer, it depends.

It depends on the amount of hop, how local it is, and whether it's up or down (inward or outward), along with other factor like the rim's material, shape and condition. Odds are that if you're just discovering it, it's probably an inward dent caused by hitting a deep pothole, or jumping a curb. The side to side wobble reinforces that theory. Local inward hops are the hardest to fix, and many shop mechanics won't even try, but they often can be fixed and the wheel gotten decent, though not as good as new.

Bring to to a shop for a repair quote, and compare with the cost of replacement. Your best bet would be at a co-op, or "blue collar" bike shop catering to commuters and family bikers, rather than a high end shop which may feel that thee wheel can not ever be brought back to their higher standards.

bikeme

You can see the hop while spinning it--looks like Biopace

bobotech

MOre than like a couple of millimeters worth?

FBinNY 

Either way, we can't align it over the internet, and I'll venture that it's beyond your skill set. As I said, hops are difficult to correct, and sometimes impossible, but it's a judgment call, whether to even try.

So, you'll have to either live with it or visit a shop, or shops, and go with their advice re. repair or replace.

AnkleWork

Did this happen suddenly? Is the tire seated properly?

FBinNY 

This is a good point. Are you watching the tire or rim when you say you can see the hop. If in doubt, look at the rim at the brake shoes for a frame of reference. You may be in luck of the rim is basically OK and it's only a tire problem.

dddd

Since mtb rims can require so much more force to bend back in shape, it would be easiest to replace the rim or entire wheel depending on what you've got there.

I've repaired many flat-spotted rims using home-spun methods, and it's a lot of work, requiring removing 3-4 spokes, judiciously pulling out the flattened area, then replacing and re-tensioning spokes to a high standard.
Most shops around here would only offer to replace the rim or wheel, and as it is, your wheel now probably has very uneven spoke tension and so is seriously weakened, while the loosest spokes will only get looser.

DannoXYZ 

Yeah, removing spokes in the low-areas, hanging from the rafters and doing pull-ups can undo a low-spot. Sometimes I've had to tie a rope to the axles and make a sling to really get my weight yanking on the rim.

Worse-case scenario of a taco/potato-chip, I've unlaced the rim completely from the wheel. Lay it flat on a glass coffee-table and mark the high/low spots and which direction to bend. Lay two opposing sides against a door-jamb and push. Wide double-layer box-section MTB rims are quite strong and sometimes, I would to lay a 2x4 on the ground and stand on the rim with a slight hop to unbend them. Do it gradually and check flatness on glass coffee-table. If over-do it and require re-bending back in the opposite direction, you may have damaged beyond repair and it may crack on you when bending back or during spoke-tightening.

FBinNY 

I've had to save a folded wheel on the road, and found sewer gratings the best thing to lever the rim against. Unfortunately (or fortunately) all those long slot grates have been replaced with bike safe versions, and rims no longer slide in far enough to do the job.

Once, in Upstate NY, finding nothing of use, we went to the local police station and asked if we could use the bars of one of their cells.

They thought we were nuts, but back then touring cyclists were enough of a novelty that they let us out of pure curiosity. Worked like a charm, and afterward Sarge invited the three of over for dinner, and ended up putting us up for the night.

Kayaker

I had a failing tire once that caused a wicked hop at speed. The tire was seated properly and the rim was perfectly round though the tire was certainly not round. It was a relatively new tire and was replaced by the manufacturer under warranty. Just another possibility.

Bill Kapaun

Last April, I discovered that at least one motel in N. Idaho still has the old style.

FBinNY 

I hope you didn't learn that the hard way.

Bill Kapaun

The semi-hard way!
At least it was the rear wheel I dropped in it. Hard enough to bounce up off the seat about 6-8".
My 32 hole Sun Rims M13II with 14/15 DS & 15/16 NDS DB spokes came out fine.
I had about 30 miles on the wheel at the time, so needless to say, I was much relieved.
Also relieved I didn't spill, since I really didn't need to abuse my recently installed titanium rod.

Camilo

This - for me the most common problem when I feel a "bump"

Turbo231

I too think it's a tire problem. Try and reseat it, slowly inflating the tube and checking to make sure the tire hugs the rim the same all over.

As said, you can check it out by just spinning the wheel and eyeing the wheel and tire to see which is out. My bet is on the tire being out for whatever reason.