Hot answers tagged

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 ...


41

Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else. ...


27

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

Spokes bent like that can't take any load (tension), so it would not work. However, bending multiple spokes around each other can produce a feasible wheel with non-straight spokes, like the last photo here. Note that in this particular wheel a single broken spoke will cause multiple others to lose tension, most probably rendering the wheel unrideable.


25

Adding threads to any sort of bolt under tension doesn't actually make it much stronger, beyond the first ≈5 threads. Adding more basically just adds dead mass; either way the whole thing will generally fail somewhere close to the first thread. So, filling the bore with threads wouldn't have any benefit. What it would do however is move the expected point of ...


19

The boundary layer drag (skin friction) is pretty small at large Reynolds numbers and even if still significant, most of it does not happen on the wheels, but also on the frame and on the rider, so the wheel causes only a small part of the drag (and even of the boundary layer drag). For bluff bodies, and a bicycle (and a rider) is a bluff body, the decisive ...


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

Prevention is the best cure. I know it takes 2 tyre levers to deal with a flat on my road bike, so I carry a pair of decent ones (with some silver paint on them so they show up better by torchlight). In addition I carry a third, old and worn but known good, because I've been known to snap plastic tyre levers (luckily at home). They can also ping off into ...


15

Sparks coming from rim brakes sounds like there's some hard object, such as a piece of grit or metal, embedded in your brake blocks. After two months, they shouldn't be badly worn, unless they're very soft, but pads will eventually wear enough that the metal cartridge mount is now touching the brake track. You should check your rim for damage. If it looks ...


13

I presume you were riding in the direction you came across the bridge and down the ramp. I doubt tire pressure had anything to do with it. On a moutain bike sized tire, unless rolling tires of rims, too low tire pressure tends to cause imprecise handling and a general 'sloppiness' in the front end. "wiping out" as you did is not typically caused by low ...


12

Um... buy a new tyre lever? They're so cheap they're practically free. OK, that doesn't help you this time but buying three or four tyre levers means there shouldn't be a "next time" for quite a while.


12

The bore guides the thread of the spoke to the threading of the nipple allowing easier spoking with less risk of cross-threading. The bore also allows the spoke to be threaded deeper w/o adding more threading to the spoke. Imagine you want to thread the spoke all the way into the nipple. If there wasn't a bore, but the inside thread of the nipple would ...


11

The hub for a disc brake wheel has the mounting for the brake rotor machined into the left side, and has shorter spokes that side to make room for the brake. If the eBay wheels are for rim brakes, they won’t have these disc mount features out the box. If the spoke counts match and are sufficient, you could theoretically rebuild the rims onto disc specific ...


11

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 ...


10

Some rim brake pads pick up and embed into themselves small pieces of rock and metal shavings from the rims. It sounds like you have one of these. A temporary solution is to remove the pads, dig out largest pieces and sand the braking surface until it is clean. The problem will repeat soon. A more durable solution is to switch to a different brand. I have ...


10

Normally the rotors will be separate. Also, there are two kinds of rotor mounts: 6-bolt and centerlock. You can get an adapter to put a 6-bolt rotor on a centerlock hub (I don't think you can go the other way), so it's something to be aware of.


10

A security nut is exactly what it is. I've seen similar ones on public bike share bikes. As to where you get the tool for it, no idea. Other ones I've seen have been shrouded; this looks like you could get a pipe wrench on it to replace it with a normal one.


10

I would expect lower tire pressure to give larger contact patch also when cornering so should equate to more grip in corners (assuming the tire stays on the rim). As correctly pointed out in another answer, increasing the contact patch does not increase optimal grip. However, a larger contact patch does give you a form of redundancy: if part of the ...


9

This sounds like you're braking quite a lot (maybe too much and rather brutally) and that the metal part of the brake-shoe that holds the brake-rubber makes contact with the rim. Replace the pads at once! It could also be that the rubber is way too soft and uses up very quickly because 2-months-old pads should not be down that much. But that depends on the ...


9

If you have quick-release or bolt-up front axle that is not properly tightened, then going over a bump could cause it to come out of the fork dropouts. Normally dropouts are equipped with lawyer tabs to prevent this, but they aren't 100% effective or your bike may not even have them. Once it drops out of the dropout, the fork would then no longer be ...


9

If you can put a patch on without overlapping the existing one, it's fine. If the patches would overlap, I can't see any problem but I could have missed something. Were the two punctures in rapid succession? If so, that and the similar location suggests that there's still debris in your tyre: check the area carefully for glass or similar pokng through the ...


9

The most likely problem is that the brakes are rubbing. If you pick up the front of the bike, hold your head near the brakes and spin the wheel you shouldn't hear any noise from the brakes. If you do, then the brakes are rubbing and that's the first problem to be fixed. To be honest, I'd guess that's 99% likely to be your problem. If you have fenders, ...


9

This is not a problem at all. What you see quite often is that riders use tires with a lighter tread and harder rubber compound on the rear of the bike to get the benefits of good grip on the front and less rolling resistance on the back. A common example combination would be to use the grippy Schwalbe Magic Mary on the front and the faster-rolling Hans ...


9

First congratulations and encouragement for getting out there on the bike. Don't get discouraged, the problem is fixable. I totally agree with other answers saying get the wheel rebuilt with new spokes. I'd go with heaver gauge spokes as well. Although this will cost some money it's likely the most cost-effective option in the long run. I'd make some ...


8

When the spokes break, do they snap at the J bend? Or elsewhere? If the little mushroomed cap is gone at the hub end and there's a spikey "claw" then your spoke tension is low which is stressing then tensionining the spokes on every wheel revolution. I'd start by lightly tapping the wheel spokes with a screwdriver, key, or something light. And then ...


8

Its a rear wheel security axle nut, with an anti-rotation washer underneath. I see a band brake or a roller brake, and a Shimano Nexus (8?) internally geared hub, which are reasonably valuable, hence the security nut. If you want to get it off with a minimum of damage, I'd make a tool. Get an old set of bootpinch pliers and round off the cutting faces ...


7

Obviously not with conventional bicycle spokes that are only expected to work in tension. With completely rigid compression spokes, it's possible but pointless (I expect the ones @Chris H links to ("not a recommendation") fall into that category), and a weak point with a sharp bend. But there is at least one wheel design with curved (not sharply bent) "...


7

This is inexplicable and we're missing some details. Any modern bike tyre will be 20mm wide as a bare minimum. Your electric scooter appears to have approximately 2" or 50mm tyres from the photos. As such a 5 mm bump will be no more than a quarter of the tyre - its not even going to snake-bite at normal pressures. At 10% the height of the scooter's tyre ...


7

Patches that overlap are less likely to work - even more so if they're those blunt-edged ones. Thin patches that taper off gently will be more likely to work when overlapped. Two patches overlapped may also cause an excessive bump, so I might take off the existing patch and fit the bigger size patch over both holes. On one rare tube I ended up making a ...


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