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41

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. ...


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 ...


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 ...


17

The idea used to be that a triple was just a double with an extra small, 'granny' ring (i.e. only grandmothers would need to use that one) so there was definitely some snobbery in a triple; that it was designed for those who needed a little more help. So on the club training run, you might be teased for it. (Google for 'triple granny ring' for various forum ...


15

If you are looking at the Biopace/Rotor/O-Symmetric relationship as similar due purely to aesthetics, or their similarity due to their lack of similarity to round chainrings then, yes, they are similar products. But, that said, from the RotoR website "The Q-Rings are elliptical; the Biopace and O.SYMETRIC chainrings are asymmetrical.". And Sheldon Brown ...


15

I don't think you can make a 3x1 setup work. In order to have the chain change gears, there needs to be a mechanism to take up the slack in the chain. In a normal dual-derailer setup, the rear derailer does that. You might be able to make it work with a chain tensioner, but I'm not sure if you can find one with enough range to do the job as well as a rear ...


14

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 ...


13

While pro riders often change gearing or whole bikes depending on the nature of the race or the stage, you do sometimes see compact cranksets, particularly among domestiques in mountain stages or races. A big-name example is Tyler Hamilton in the 2003 Tour De France. After crashing and breaking his collarbone before the huge mountain stages he was unable ...


13

As the others have stated, there's nothing wrong with any various drive train types (triple, double, 1x, single, etc). Compact drivetrains and triples are becoming more common because they provide an easier set of options for casual riding. A traditional double for a road bike may be more than most people want for casual riding. For example, if you take a ...


13

I doubt that you actually managed to screw your pedals into the wrong sides. If it can even be done, the amount of force required to do so would have easily alerted you that you were doing something dreadfully wrong. Not to mention the aluminum shavings that would have been all over the place. Pedals can get pretty snug just through the action of peddling ...


12

Obviously, the simpler the better, and a triple is a little, er, "crankier" to maintain and use than a double. But on most bikes it will mean that you have both a slightly larger large gear and a significantly smaller small gear, in addition to having closer "jumps" between gears. Exactly how this all will work out depends on the manufacturer's choice of ...


11

Here's what I'd recommend As others have suggested, you should avoid a stock bicycle. They're designed with the top of the bell curve in mind, and you're simply half-again as much man as the normal one. For more information on any of these topics, consult a bike shop! Crankset: Since you asked specifically about them, I'll start here. The stiffest, ...


11

There are bicycles with a crankshaft that runs through the rear axle. The "Tur Meccanica Bi Bici" is such a bicycle: I can't tell from your picture if it's the same bike or not, but it certainly could be.


10

I don't like to be the bearer of bad news, but I've been down this road once or twice. As a hobby, I sometimes pull bike frames out of dumpsters and rebuild them to sell for my cost on Craigslist. I have learned over the years that bicycles, when new, really cost at least $300-400. "Bicycle-Shaped Objects" (BSO's) are sold at stores like Wal-Dart and ...


9

Ultimately it's a trade-off between a wider range of gears and bigger jumps between those gears. There will always be uphills that are too steep for your lowest gear and downhills where you spin out. If you try to fix both problems with a wider range cassette (your triple already has a great range) you may find that you're never quite in the "right" gear ...


9

Your crank arm is trashed. With the crank bolt removed, gently ride around a few miles, it should work itself loose enough that you can yank it off. Otherwise many shops have basically a slightly larger crank puller for addressing this issue, where they chase out a larger set of threads, then use the larger puller to get it off. The crank arm typically ...


9

Like you said, they are cottered, what makes them aligned is that pin through a hole, which at the same time tightens the crank arm around the axle. If you google "cottered crank", you can see the spindle, which has a slot in each side. My hypothesis would be: or the cottering bold got deformed, or the spindle slot itself got deformed, or both. A bolder ...


9

This is actually a matter of the force multiplication that each chainring provides, and the size/mass of each chainring. Force difference Let's propose, only for a moment that you had a chainring as big that the radius of it is almost the same as the crank length. If the rider stood to pedal while using that chainring (and using simple platform pedals). ...


9

Yes, you need to replace the crank arm, if tightening the bolt does not make it 100% solid again. No doubt the crank arm had been loose for days, and had you tightened it earlier you might have "saved" it. And there's some danger that you have damaged the crank axle as well, meaning the bottom bracket cartridge will need changing out as well. I have ...


9

You must use a Crank Arm Puller tool: Park Tools Crank Arm Puller Here's how to use it: Video


8

This is probably going to depend on a bit more than just your height or leg length (though I'm sure a rough idea can be gleaned). Your specific bike (geometry) and riding position will also affect crank length a bit. Here are a few good links on the subject that go beyond my knowledge on the issue. http://www.cptips.com/crnklth.htm ...


8

There are many possible causes of creaking. But Deemar has the most likely reason in this case - the cranks are loose on the axle. Think about how a creak is produced. It's one item sliding over another. But instead of sliding it's repeatedly sticking then jumping. The amount of movement might only be a fraction of a millimetre. The OP would have noticed if ...


8

Well, you're a big guy, so a lightweight racing bike is probably not for you. You might want to look at touring bikes, and, in particular, some of the Surly models. For the crank problem you probably should have a splined vs square crank, and you need to regularly check the torque on the crank bolts.


8

Could be any number of things. The first thing to check (because ignoring it can rapidly cause expensive damage) is that the crank arms are tight. Even if they don't seem loose it doesn't hurt to put a wrench on the fixing bolts and torque them a bit. (If one moves more than a small amount, get a torque wrench and do them up right.) Likewise with the ...


8

You're right, you want to space it between the shell and cup. You can put spacers on either side to get the chainline right. Most cranksets come with spacers (2.5 mm is probably the most useful size for you) but if yours didn't any LBS should have a few to sell you. Something like this: http://wheelsmfg.com/bottom-bracket-spacer.html (I don't know if ...


8

Without seeing any pictures, I think you'll likely want to replace both, but you can figure it out easily enough. Usually, the bottom bracket will be fine after a crank improperly coming loose. The bottom bracket spindle is typically made out of a hard steel and only the most miserable metal cranks are made from anything other than aluminum, so when the ...


8

The lock nut is used to wedge to crank on the bottom bracket spindle. If you open it, you should still not be able to get the crank off, at least not easily. For square tapered bottom brackets, usually you have to use a tool called a "crank puller", which is hold in place with the outer thread. See this article over at Sheldon Browns for details and very ...


7

This is a common setup for many freeride bikes, as it allows uphill peddling and a bash guard. However only certain models of chain guide support this, and the one your son has doesn't officially (though it wouldn't hurt to try if you have crankset to test, might affect derailleur...). The DRS is eThirteen's 'official' dually chain guide.


6

In the 2010 Giro, on the Plan de Corones, Vinokourov rode an 11-32 cassette to 8th place (with compact (34) up front). Gadret rode the same setup to place 3rd on the stage. http://www.theroaddiaries.com/?p=2726 Contador used a compact and a large, I think 30-something rear cog, on l'Angliru in the 2009 Vuelta a Espana. Compacts are definitely used by ...



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