Hot answers tagged

98

Consensus seems to be more and more this: Do not use training wheels. The most important part of cycling is not the pedaling, but balancing and steering. Steering is mostly done by leaning (therefore balance) and not by turning the handle bar. Training wheels do not help in learning to balance the bike and actively prevent leaning. Therefore it might be ...


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 ...


42

With a traditional non-through axle, there's a slot at the bottom of the fork (or the dropouts), the axle is hollow, and there is a skewer through axle. You use the quick-release to loosen the grip around that slot to slide the skewer (vertically) in and out of that slot, while it's still going through the wheel. With a through axle, there is simply a hole ...


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. ...


39

To taco a wheel means you've bent it so badly its a write-off and cannot be salvaged through truing. This is significantly worse than going out of true, because the rim will be creased or torn, spoke holes will be pulled through on the outside of the taco curve. A damaged rim alone is not a taco, there has to be a folded wheel to earn the title. ...


30

Bicycle dynamics A bicycle may only be ridden because of the peculiar steering geometry. The centre of the contact patch of the tyre is behind the point where the steering axis intersects with the ground. The distance between these points is called trail. In order to visualise it you may have a look at this figure from the bicycle dynamics article on ...


28

Those look like packing pieces used to stop the axle ends from punching through the cardboard box partially assembled bikes are delivered in. I'd imaging they are being used to stop the axle nuts getting scuffed or scratched.


27

So your boy is simply sitting and not pedalling, so you push him along? Of course he's not going to pedal when he's getting a free ride from you. Stop Pushing! Firstly, does he understand how a bike works? Do you ride? Does he see you or others riding? You might consider going the other way, and remove the whole transmission and the training wheels. ...


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 ...


26

This is a common problem, but really not a big deal. I've usually heard it called "toe overlap". I have it on all my bikes. Basically, it's a bit shocking the first time it happens, but you get used to it. It's no big deal. If you're simply aware that it can happen at slow speeds, you'll avoid it easily enough. Since it can only happen at slow speeds, it's ...


26

That's not the correct skewer for the wheel. I think you likely are using the rear skewer in the font wheel. Front hubs are typically 100mm between the drop-outs, rear are 130 or 135mm (or even 145mm on some mountain bikes that have stronger through-axle designs).


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 ...


24

This is a standard quick release mechanism simply grab the lever indicated below and flip it the opposite direction (green arrow). At which point it should loosen up a bit, then you can spin it around to the left to unscrew it further. You do not have to take it all the way out, just loosen it enough to be able to slide the wheel out. You can also hold onto ...


22

The "asymmetric wheel" terminology is a little misleading. This particular wheel has an asymmetric rim. Any bike with a rear derailer setup will have an asymmetric rear wheel, because the gears take up space. The usual way to handle this is that the spokes on the gear side have less of an angle (closer to vertical) than on the non-gear side. (That is, they ...


22

You could probably add training wheels, but not a crank. There simply isn't anywhere on the frame for cranks to go. Also, adding training wheels to a balance bike is kind of defeating the purpose of a balance bike. It's meant to be an alternative to training wheels that allows the child to learn to steer into falls and "scoot" around and eventually learn ...


19

Centerlock largely exists because since the beginning of modern disc brakes for bikes, Shimano has more or less alone had a weird cautionary take on the physics of rotor bolts theoretically being able to loosen in the six-bolt design. That's why their six-bolt rotors have always come with various retention systems for the bolts that nobody else bothers with. ...


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

looking at your bike, which I basically see as a alu-105 setup (albeit a good setup, Felts are lovely bikes), I can suggest a few things but right away I'll say I don't think there is a "magic bullet". In no particular order: wheels, as you say. On a lot of low-to-mid-range bikes, you just need to look at what wheelset they have to realise that this is ...


18

From Sheldon Brown: Spoke Protector A plastic or sheet-metal disc that fits between the cluster and the right-side spokes of a rear wheel. This is intended to prevent the derailer or chain from getting caught in the spokes, possibly causing very extensive/expensive damage/destruction to the wheel, the derailer, and the frame. A spoke ...


18

You are correct that those levers are designed to be opened with your bare hands. Unfortunately it's usually easier to push the lever closed than to pull it open, so it's easy to over-tighten it. Start with the lever open, and facing back as shown in the picture Wind the nut on the other side back 2 or 3 turns. Close the lever. It should be very easy, and ...


18

No, not possible. If you want to go the other way, buy a 12 inch bike and then remove the chain/pedals/bottom bracket/bearings and degrease it. Store the parts so they don't rust. Optionally put something over the ends of the BB tube to protect the threads, even some duct tape would help. When the kid is old enough, refit all the transmission parts. ...


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 ...


17

The increased weight of the larger wheel (if indeed it does increase) will of course add weight to the bike, but additional weight adds very little rolling resistance (though it does of course affect hill climbing). It is a myth that "rotating mass slows you down". In terms of top speed there's no difference between weight on the wheel rim and weight ...


17

If the nuts are rounded they're stuffed. You want to remove the nuts but not damage other things, like axles. I'll assume you're talking about axle nuts, but the same ideas apply to all nuts, bolts, and even screws to some extent. So your nuts look something like this: Clean the flats up with a file. Use a medium flat file and smooth off the lumps of ...


16

Depends on how "little" the accident was. First double-check that the handlebar really is "square" to the fork, and not slightly cocked one direction or the other. (Though this problem shouldn't cause the wheel to turn when you let go.) Next, oddly enough, do the same check with your seat. If the seat is slightly angled to one side or the other then it ...


16

As usual, Sheldon's got the answers. ISO 622 is the unambiguous way of referring to the following rim sizes: 700c (you see this marketing on road, hybrids; this is from the French system; the c is often dropped, but there are rare a,b sizes) 29"x decimal (you see this on mountain bikes; usually only applied to wide rims) 28"x decimal (particularly in ...


16

That's a pinhead security fastener. You should have got a key to match with the bike. Without the matching key number you can't get a replacement key either. Here's a picture of a pinhead key fom about 2010. Yours will look at bit different. The key number is under the red blob, and the pins to mate with the nut are in the silver bit on the right. As you ...


16

Not knowing how widespread this apporach may be, I'll just contribute, what strategy my parents applied: My father bent the trainers more outward/upward - this left more room to tilt from one side to the other, or to balance in between. I figured that it would be cool (and less noisy) to try to keep both trainers off the ground. Soon afterwards, the ...


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