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39

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 ...


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

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

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 ...


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, ...


10

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 ...


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

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 ...


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 ...


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

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 ...


7

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 ...


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.


7

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 ...


7

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). ...


6

if you are positive it's coming form the bottom bracket, and you have already R&R'd them, try using Teflon tape instead (plumber’s tape), wrap it around the cups and reinstall them - this should fix any squeaks in the BB.


6

In general, crank fixing bolts need A LOT of torque. This chart list torques for several varieties of crank arms. (I suspect you have a variety of Octalink.) You're probably looking at something in the neighborhood of 350 inch pounds, which would be 35 pounds applied to a 10-inch lever arm. Too much force and you shear the bolt. Too little force and the ...


6

The positive of a triple crank is a greater range of gears. A triple crank will give you a lower low gear which may be useful for climbing steep hills. The negative of a triple crank is weight. You have an extra large gear which will likely weigh around 8 or 10 ounces. Since those ounces are on a part of the bike that rotates, they matter. So if you ...


6

A 59-61cm frame, most likely. Also, I would recommend you up your budget a fair bit, unless you are willing to replace the bike in a relatively short time. The weight of a frame should not be a major consideration for you, but the lateral and vertical flex should be a primary factor. Those things will affect your direct power output. Something like a ...


6

what spacing is the is the rear hub? I bought an s2c recently to commute on my track bike, two speed internal geared hub with a gain of 38% but it might be over kill for yourself. Given your setup you have a gearing of about 55inches, if you were to switch out the rear cog to a 12 tooth you would gain 5inches, bring you to around 60 which is considered a ...


5

Are you sure the creak is coming from your cranks? It could be the rear hub, it could be the pedals themselves, it could be some combination of things which when you put your weight on them causes a creak. Are you putting extra weight on the bars when you get the creak. I've had creaks from: the seatpost, the headset, the rear hub, the front hub, the ...


5

It sounds like the cranks are loose on the spindle - hence the creak every pedal stroke / 180 degrees. If the cranks have been loose for a while, then the action of riding the bike will have usually rounded either the square taper on the spindle, or the hole on the cranks. If this has happened, then you will never be able to tighten that set of cranks up ...


5

The best option would be to place the crank in a table vise - or in a pipe that has been gripped in a table vise. If you don't have access to a vise, another option is to try and attach the pedal wrench so that the handle is only a few degrees away from inline with (right on top of) the crank, so that you squeeze the wrench and the crank together.


5

Some BMX cranks are keyed, so that they will fit only one way. If yours is not keyed, then, no, there is no better way to line it up than to do it by eye. If you want to double check it, take a plumb bob, and place it across the center of the pedal threads on one crank. Turn the crank until the string lines up with the other pedals' thread center. If the ...


5

First off, got to a bike shop and get a new crank bolt. They're a fairly standard item. Can't tell for sure if your bike had "self removing" bolts or standard ones, but it doesn't matter that much, a standard style should fit. The large threads in the crank arm are for holding a removable trim plug over the bolt (or holding the "self-removing" part of a ...



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