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51

Rims are worn out when the groove disappears. If the groove is clearly visible, well-defined and of uniform depth all the way around, the rim is not quite worn out and certainly not dangerous. New brake blocks will cause less wear as they will be free of hard particles of grit and metal that get embedded in the relatively soft rubber over time. Given the ...


28

Not enough points to comment, so here is an answer instead, based mostly on my own experience. I've been using a bike as my main, if not sole, mean of transportation for the last 20 years or so. During that time, my weight changed a lot (from 80 to 130kgs (176 - 286 lbs)). When I was 80, I nearly never broke a spoke (maybe once per 10 000km), and only after ...


25

Sorry, those rims are trash (or wall art). I'd chase down the seller and demand your money back, and report them on whatever sites they were advertising on for selling items in a known dangerous state. The crank may be small now but it will propagate in both directions and get bigger. Cracks on thin section aluminum cannot be welded as the heat will destroy ...


21

The real answer is you need inner tubes with longer valve stems. Tubes come with various length stems to accommodate deep section rims. There are screw-on valve stem extenders available for both Presta and Schrader that you could use to extend your stems. (I think some Schrader ones are actually for car tires, but they would still work for a bike.) With ...


19

It's a wear indicator. The friction of the brakes gradually abrades the rim away and the track lets you see how fast that's happening. Once the rim has worn enough that the track is very shallow, the wheel is starting to lose strength and should be replaced. For wheels that don't have a wear indicator groove, you can detect wear by holding a straight edge ...


19

I suggest you get the wheel rebuilt properly, once and for all (probably by a different bike shop). A well-built wheel should be able to handle even riding off kerbs or small unavoidable potholes without breaking spokes. You should unweight the saddle and take the weight on your feet, but even if you don't it should survive an occasional hit. A hybrid like ...


18

That is the seam where the two edges of the rim were jointed. Cracks, as you have noted, do not form in such a perfectly uniform way. As long as the edges remain closely butted together as they currently are, you are good to go.


17

This is a more detailed answer. I cautiously don't agree with Chris that the OP needs to stop riding the wheel, but it does depend on how the rim is constructed. Basically, the aluminum piece is a sleeve of some sort. The sleeves are structural elements in some but not all rims. I believe it is not a structural element in this rim, which the OP described as ...


17

Imagine a theoretical new bare rim made to perfect tolerances with perfect uniformity of materials and construction. Without spokes, it is perfectly round and flat. Add spokes and tension them all the exact same amount per side. It will still be perfectly round and flat. Make it a real, good quality rim. It now has a seam that makes the radial runout repond ...


17

These are wear indicators. After years of braking, the surface of the rim will grind down to a point that these grooves will no longer be discernable. At that point, you should replace the rim.


16

One general consensus is that if your wheel has suffered damage enough to break three spokes in the same event then the rim may have suffered enough damaged to write it off. You should clean the rim, remove the tyre/rimtape and give it a careful examination with bright light. That's distinct and different from "I found three broken spokes on the wheel&...


16

It may be worth glancing at this more detailed answer that discussed how aluminum rims were constructed. But in brief, aluminum rims are first extruded in a flat bar, then they’re cut and rolled into hoops, then the ends of each hoop are joined somehow. One method is to simply pin the ends together without smoothing out the joint. Your rim was built this way,...


15

To me, it looks like whoever (or whatever, as it was likely machine built) used the wrong size tooling to hold and screw the spoke nipples as the wheel was built. Not a rim manufacturing defect but a wheel building defect. If it's still under warranty, I'd get the wheel replaced. Any cracks are bad cracks and could propagate. If it's not under warranty, I ...


15

In the days before factory built wheelset, rims where produced without being specifically for front or rear wheels. On most general-use standard bicycles it is still that way. The only difference was the spoke-hole count. But many rear wheel rims today are no longer symmetrical, meaning the right side is different from the left. This is mainly due to the ...


14

Lower spoke numbers are primarily of interest to weight weenies (though for a given price, a lower spoke wheel will probably use a heavier rim offsetting the spoke reduction weight savings). As usual, Sheldon is some good reading. There is also a whole book on how to build wheels well and design decisions, by Jobst Brandt, called "The Bicycle Wheel". What ...


13

When a rim is extruded, the shape of the material can give added strength to the rim. There are many rim types, but the two most common are single-walled and double walled. A single walled rim uses a simple U shaped extrusion. A double-walled rim adds a cross brace across that U shape, creating a D-shaped extrusion. Triple hollow construction add extra cross-...


13

This particular rim strip absorbs color from everything, and it is not a problem. Mine have turned green in use from something leaching from tubes. In general, rim strip should be replaced if it splits, stretches deep into the spoke holes or exposes the spoke holes. Discoloration happens, but since rim strips aren't usually visible this is not much a ...


13

Fold a paper towel a couple of times and stick it between pad and rim. Squeeze the brake lever and rotate the tire. Depending on the contaminant you may want to wet the towel, douse it lightly with a solvent, or (to get solvents off) use alcohol.


12

No you will not be able to use your 700x23c tire on a 650c rim. The bead seat diameter of 700c rims is 622mm, this will also be the bead diameter of the your 700x23c tire. The bead seat diameter of a 650c rim is 571mm (see Velocity's Spec section). Your 700x23c tire will be 51mm too wide.


12

Sorry to hear about your damage. I don't think the crack is due to impact. Maybe, maybe not, but regardless of a reason the wheel has become damaged. On the two sided likeness of damage — things are not symmetrical in practice, especially pot holes, and a crack does not have to be symmetrical. Is this repairable and worth repairing? It depends on whether ...


12

This doesn’t look like a simple scratch from grazing the side of the pothole. It almost looks like it buckled or severely deformed and now you have loose/delaminated fibers sticking out. Even if the structural integrity of the wheel were not compromised (which I doubt) you do have a crack in your braking surface. I doubt it’s possible to repair this since ...


11

Hub Width On road, mountain, and hybrid, the front hubs are 100mm in width. On road bicycles the rear is typically 130mm, where on a MTB it is typically 135mm. Measure this from your old hub, and DON'T stretch/force a different hub width. Wheel (Rim) Diameter The most typical road rim is a 700c which will mean the bead seat diameter of the rim is 622mm, ...


11

You can (theoretically) mount any 700x(something) tire on any 700c (ISO 622) rim. However, you need to make sure the frame (and brakes if rim brakes are used) can clear the tire without rubbing. You generally want to match the rim width to the tire though -- too narrow or too wide of a tire on a rim can lead to tire/rim damage or bad handling. In your ...


11

Is the cut always the same distance around the tube from the valve? If so then you have something wrong in your rim. Use the punctured tube to measure where the damage is coming from... that will give you at most two positions, one in front of the valve hole and one behind. I think you'll find a cause in this very small sector of the rim. BTW - had you ...


11

You have the correct tires. This does not have anything to do with tire width. The diameter determines whether tires will fit or not, unless there is a huge width mismatch. Rims and tires are both made to a tolerance, and you just happen to have an unusually large rim and small tire. I have had the opposite problem with some Schwalbe tires, they were so ...


11

As @abdnChap correctly stated, not all rims have wear indicators, which are usually one or more dimples on the rim or a groove machined around the whole rim. Without a wear indicator, gauging the amount of permissible wear is subjective (unless the rim is cracked, but you don't want to let things get to that point!). So, how are consumers to gauge wear using ...


11

I will be the suspicious person, and I will wander a bit off-topic. No offense intended, I will only describe a worst-case scenario. I make one assumption: did you buy it second-hand because the price was a very good one (given the general condition you could see from the picture)? The bike was very clean: recently bought? that would explain it. cleaned ...


11

Cracks in the wheel rim do generally need attention. If the cracks are around the nipple and you're a gambling man you can keep an eye on the crack's propagation and maybe use it a little, if they're in the side/wall, it's possible failure will be a little more exciting. If you purchased them recently you may wish to return or exchange them. Welding is ...


10

I would be very careful with a deal that sounds too good to be true. Take a look at what happend to this carbon wheel in another question: Carbon Wheel Heat Bending I wouldn't buy from a company I've never heard of before and will never hear from again (like when the wheel deforms from the heat of braking and I'm trying to get a refund). Even the tagline ...


10

I figured out a solution. The thing that is supposed to stop the inner tube from expanding into spoke holes is called a rim tape. The tape that came with the bike is really flimsy. I'll purchase and apply a high pressure rim tape. Hopefully that would fix the problem. Update: I've decided to go for a cotton rim tape as they're more durable than rubber ...


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