back wheel goes up n down. help?

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3/4/2015 7:58 PM

Well I was going back home I was on a flat surface and I noticed that I was like bumping up and down as my back wheel turns. I put my bike upside down and turned the wheel and I could see how the wheel was doing the up and down. I just true it and it doesn't go to the sides, the tires is kiiiinda good with the rim obviously not perfect but ok. I don't know iis the rim or the spokes. Should I buy a new rim? Sometimes I can land a little bit to hard so that might be a cause. Any sugestions?


3/4/2015 8:03 PM

You gotta learn to true that out the right way.

Tighten the group of spokes opposite of the area that is furthest down and loosen the group of spokes the furthest away from the frame.

Making the wheel a true circle is ALWAYS the hardest part of truing, but with patience and time you can do it.


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3/4/2015 11:00 PM

I had the same problem with the last wheel i build, to true that, the first thing to do is to locate the bump spot (which was a quarter wheel for me) and took of the tyre and rimstrip, then you'll be able to see if your spokes a way too tighten, or too loose obe the other side, or both..
To fix it, loose all the spokes to the same point and tight them correctly with patience.


3/4/2015 11:23 PM

What rim is it?

If it's a single wall rim, it very well could be the rim and not a trueness issue. Double walls are harder to fuck up THAT bad, but can still happen to them.

Look at the photo below


Let's say your wheel is hopping up at the circled parts, you would want to tighten the spokes JUST in the circled parts, and loosen them everywhere else. So tighten the circled spokes, but loosen the rest. Starting at the valve makes it easier, but locating where it's hopping is tricky without a truing stand. At home I just eye it up in my frame as best I can, or use zip ties and get it as best I can. Up and down is a pain in the ass but taking your time and doing 1/4 turn on each and being patient will go a long way.

It's best if all your spokes aren't piss tight either to start with, if they're pretty damn tight, loosen them a tad so you don't risk messing the nipples up or snapping a spoke. Also make sure your rim is fairly true side to side, you don't want it completely straight because when you go to do the up and down, you'll throw it out of true again anyway. So get it fairly straight, then do the up & down hop, then fine true it side to side.

Also keep in mind you said it is an old/beat rim, so it will never be 100% true, so don't be surprised if you can't get it 100% after spending a lot of time on it.


3/6/2015 7:39 AM

Ive trued out hops but its honestly easier and faster (ateast for me) to just relace it and do it right.


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3/6/2015 7:52 AM

Just a random suggestion-did you make sure the tire bead isn't bulging off the rim? That will make it bob up and down.


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