Hot answers tagged

84

It's to ensure that young boys who ride BMX bikes will be able to have children when they grow up. Fine print: More accurately, it’s to assuage the worries of the parents that are buying the BMX for their young male child that they might not have grandchildren. Actually efficacy for such purpose is under debate.


59

It's to give the illusion of safety.


58

Cables: The main difference that I am aware of is the diameter of the cable. Most brake cables are 1.5 or 1.6mm in diameter. Most shift cables are 1.1 or 1.2mm, galvanized shifter cables are 1.3mm. I'm sure that there is a lot of science behind the difference but I'll leave that to someone else. One major difference in MTB vs road BRAKE cable is the ...


54

This appears to be a disc brake spacer (block). Such a spacer may be inserted in the disc brake caliper between the brake pads. When the wheels are removed, and hence the brake rotor, an inadvertent pull on the brake lever might move the pistons* so that the rotor cannot be inserted any more. It is even conceivable that the pistons might be dislodged ...


42

If the aluminum is sufficiently stiff it makes zero difference -- the crank could be any shape (a disk, an S shape, etc), but the relationship between the two contact points would still remain the same, and that's all that counts. The only effect the crank could have is adding a bit of spring to the crank, which might be good or bad for effective cranking. ...


34

Economics of scale. For instance, when a bike manufacturer buys thousands of groupsets directly from a component manufacturer, they get a significantly better per unit price than a retailer can. The retailer not only must necessarily buy in lower volume, but also typically buys through one or more layers of middlemen, each layer adding their cut to the ...


33

Here's a little bit of information that's in contradiction to "higher end equals better" Lower end components can sometimes last longer and be less problematic than the higher end components. In order to shave off every single gram they sometimes have to skimp on materials. Also, the tolerances are much tighter, and high end components can often be ...


32

If you want to maximize your max. speed, go for an 11 tooth cog. If you want to maximize your average speed, unless you're a pro you probably are better off without it. Even cruising at 40km/h does not require and 11 tooth cog. For example, take a look at this table, showing cruising1 speeds for a 11- 21 tooth cassette: And compare to this table for a 12 - ...


26

They are called Pegs. Pegs are mainly used by BMX riders to help perform various tricks. Flatland trick (standing with all of his weight on one peg, not damaging anything): Grinding a wall on the rear peg (imagine the forces when the rider jumps on the wall, still: no damage to the hub but of course to the peg and the wall): Images from Wikimedia Commons


25

The comments on the Kickstarter project have a few good explanations of both why the design is effectively identical to a straight crank, and why the plan to make carbon-fiber versions is dangerous. Now leverage: if you tried to push down on the pedal (as shown in the video) when it was exactly top dead center and stopped, it doesn't matter if it is a ...


24

I assume that you're talking about road biking. I can give you my opinion after using these groups for a while: Shimano Sora, Shimano Tiagra, Shimano 105, and now a full Shimano Ultegra. All work, when properly adjusted and when shifting correctly. You have to do your homework and know how to shift smoothly, and adjust the gears. Whoever tells you that ...


23

Other than the obvious fact that your better quality (and better handling) bikes tend to be lighter, there's no real correlation between weight and performance (other than a modest effect on acceleration and the obvious effect on hill climbing). But you can generally (with some exceptions) assume that a bike that is quite a bit (like 2x) heavier than others ...


22

It appears to be a clamp-on pump peg that got moved down out of the way either intentionally or from coming loose.


21

This is just a rehashing of a very old and horrible idea. See PMP Cranks et al. Edited for additional information: RE: PMP cranks A moment's thought shows a straight crank and an L crank always have the same relation between pedals, chain, and bottom bracket. Thus, there is no advantage to L cranks. And an L crank always has more material than a ...


20

It protects the frame from the handlebars. The handlebars, unrestricted by brake or derailleur cables, can rotate freely to the point that they can smack into the top tube. This is particularly easy to do when carrying the bike.


20

For me, and for many riders that come through my shop, the 11-25 is missing the critical 16t cog, which (at least for me) is the sweet spot. That is, the gear which I don't tend to spin out of, and that doesn't turn in to a grind fest. If I'm doing a Euro trip, then I will run an 11-28, with a compact front. But at home, for daily riding, a standard 53/39 ...


18

In addition to economies of scale, you also have to consider the difference in price sensitivity and leverage between a manufacturer and a consumer. If Shimano told Trek that they'd start paying retail prices for their cranks, for example, your next Trek would have SRAM cranks. You can be sure they've negotiated the lowest plausible price, because it's very ...


17

The purpose of such a steering damper is to stop the front wheel from turning when using a (two-leg) kickstand or while pushing the bike. Not much use otherwise.


17

These are to protect your frame from the support bolt on Shimano front derailleurs (I don't know if SRAM have the same). You can see them on page page 7 of this manual.


15

There's no way to 100% secure everything, but there are things you can do to make it more difficult or time-consuming. Don't lock up your bike. Bring your bike with you instead of leaving it outside. Mine goes into my office. Choose a location where you or other people will see thieves messing with the bike. Not a super-high traffic area (in that case ...


15

Unfortunately this doesn't help. The example pictures demonstrate misunderstanding elementary classical mechanics and more specifically, statics. Moment, a.k.a. torque, is defined as M = F * d where F = the force applied d = the perpendicular distance from the axis to the line of action of the force. The shape of the crank has not effect on either. F is ...


15

Flat pedals are great for lots of reasons, but I won't get into the virtues or pitfalls of platforms versus toe clips versus clipless systems (though I am a big fan of plain old platform pedals.) I will try to give information pertaining to the different styles and a few examples rather than an exhaustive list of specific brands and prices. There are lots ...


15

This very much depends on how exactly you define the classes of components and what type of riding you plan on doing. The definitions are not standardized, but component ranges from each manufacturer are easily ranked. The following are the MSRP of complete group sets for Shimano (the price ranges are similar for other manufacturers). Dura Ace 9000: $2699....


15

They're trying to sell you stuff. More expensive stuff (have you looked at 11 speed consumable (chain+cassette) prices vs 10 speed?). I would not bother upgrading. As groups go to higher and higher speeds, the older stuff gets pushed down to lower component levels. So today's 11 speed 105 group will be next year's (or likely a few years later) Tiagra ...


15

The one substitution that will probably give you the most bang for your buck is better tires. High-quality tires roll with much less rolling resistance, have better grip, weigh less, and roll over small imperfections more easily. And if you're riding on tires with knobby treads, but only riding on the road, tires with minimal/no tread will ride much faster ...


14

The stop rings go over the head of the bolt. The grooves on the ring line up with grooves on the bolt head and encourage it to keep from rattling loose. They are simply snapped or pushed over the head of the bolt once it is tightened in place. I suspect that in some country, they may be a requirement for manufacturers. However, I haven't ever actually ...


13

There is essentially nothing in the way of maintenance on a standard bicycle that cannot be done by a competent "shade tree mechanic". It's all a matter of learning the basic techniques and acquiring a few basic tools. The first thing to learn to do, and the most important, is of course to keep the tires properly inflated. Repairing flats, and changing ...


13

It's something that should be experienced. Go grab an old school beater bike (like my old MTB that weighs 35lbs), ride it for awhile. Then, stop by a bike shope and see if they'll let you test drive a nice lightweight bike (usually on the order of 16-20lbs). You'll be astonished at how much more FUN it is to ride the light bike due to the responsiveness (...


13

The ball-end wrenches are really handy when there's an obstruction in front of the bolt, since they can be inserted at a slight angle. But since the contact area is smaller, you're slightly more likely to strip the hole. So I would use a regular wrench when possible.


13

Great question! I think the market drives this -- not necessarily just the folding bike market, but the component market. Mountain bikes have been the predominant type of bicycle for the past thirty years. This has meant that every manufacturer has a line for very, very inexpensive mountain bike componentry. If you want to build up a bike on the cheap, ...


Only top voted, non community-wiki answers of a minimum length are eligible