27

There are a couple of things you should consider: Your bike isn't going to care. You aren't going to loosen pedals or cranks spinning in reverse, because you're not applying any load, so there is no force in which to cause precession or fretting. You are getting no benefit (health-wise) from doing so. It might be better not to even bother.


23

I haven't seen one of those before, but it looks as though it could stop the chain dropping between the bottom bracket shell (the bike frame) and the crankset if you ever drop the chain off the inside of the small ring. When that happens it can be tricky to get it back out, and if the chain is oily you end up with that oil everywhere (mostly on your hands ...


23

I think your pedal is a lost cause. Even if you did get it off in the current condition, reinstalling and later removal will make later-you hate current-you. I would disassemble the pedal from the outside - remove the axle cap, locknut, cone, and bearings, then slide the pedal cage outboard. You may have a second set of bearings inboard, or a bushing. The ...


22

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 ...


21

Once loose, the pedal spindle will describe a cone as the crank rotates. This concentrates force at certain points in the crank threads, leading to damage. Top image shows the pedal spindle in the threaded hole in the crank. The threads are fully engaged and tightened, and forces are distributed. Note there is space between the male and female threads (...


17

Saddle height for new bike setup purposes should always be set relative to the pedal, not the BB center or any other reference point. So yes, crank length makes a difference. Using the ground or BB center as a reference point is convenient for re-establishing a given height after the post has been moved, but not for setting up one bike to have the same leg ...


17

I started getting seriously into bike work circa 2002 and was lucky enough to come across Jobst Brandt's view of the topic around that time. Since then, most of which time I've spent working as a mechanic, I've observed that the Brandtian observations of the mechanical dynamics at hand are wholly correct, but I don't agree with him on what to do about it. He ...


15

The system you propose is just a third way to change gear, in a mechanically very complicated way. Any benefit that could be obtained by lengthening the cranks can already be obtained by moving to an easier gear and a bike with two or even three front chain rings and anywhere between five and eleven rear sprockets has plenty enough gear ratios available to ...


15

The bottom bracket spindle is for cottered crank. The bottom bracket looks like threaded one, so it is likely that it can be replaced with square taper or external cup bottom bracket. To tell which thread the bottom bracket has, we'd need to know the exact dimensions.


15

The bottom bracket is not damaged, the left hand crank arm is. You have a 'two piece' crank where the right side crank is permanently attached to a steel axle, and the left hand crank clamps onto the axle with two pinch bolts. The axle has small splines cut into it where the crank clamps on and the crank has corresponding splines cut into it. for the crank ...


14

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). ...


14

There are multiple components that can contribute to a clicking or grinding sound in your drive train in addition to the bottom bracket, including the chain, the pedals, the derailleur and the rear hub. That said, the symptoms you describe seem to indicate a problem with the pedal bearings or the bottom bracket. Here are my steps for troubleshooting the ...


14

That nut was put in the wrong way around. This is what the nut looks like: The hex end is what you should tighten with a approriate socket. This is what it should look like when installed correctly: If it ever get's super tight as it is now, to get it off, the easiest way is probably to cut it with a tremmel and chisel it out. Good luck!


14

Not really. You might want different gears, but probably not fewer. Shorter crankarms give you less mechanical advantage—they're functionally equivalent to being in a higher gear. So you might want a lower gear range to compensate. It is common to express mechanical advantage as "gear inches"—this is (front sprocket/rear sprocket) × wheel diameter ...


13

144mm: supported chainsets such as 52/42 with relatively narrow range freewheels 130mm: allowed a range such as 52/39, as freewheel (then cassette) range expanded 74mm: necessary to add a smaller ring, e.g., 30t on a road triple 110mm: this supports anything down to 33t, hence this was introduced for Shimano FC-R700 around 2005 as their first compact ...


13

Your crank arm is toast. In my experience, if a square taper ever gets loose while riding, even once, it's done. Retightening the bolts buys you a few miles at best but it'll loosen up again before long. I think the connection to lubrication is coincidental. You said the problem started after you applied lube, but that's not true. You did that because it was ...


12

The Giant Reign is a long travel 'enduro' bike that is designed to be ridden down steep technical trails, not pedalled down road/fire trail. It's most likely that changing to a 39-53 will not work as the inner chainring will catch the chain stays, and even if it did work, it would compromise the bike in technical terrain, increasing the chances of '...


11

Many two wheel drive mountain bikes exist. Here's one article advertising a new one: There’s been no shortage of attempts to build a workable two wheel drive bicycle over the years, but this latest effort from Double of Japan looks like one of the most compelling yet. https://www.bikeradar.com/news/this-is-a-two-wheel-drive-bike-done-right-sort-of/ They do ...


11

I'm not an engineer or a historian, so I'm going to go off my memory and, where I can find it, companies' stated rationale for making a change. Bolt circle diameter The larger the BCD, the bigger the minimum chainring size. 41 teeth is the absolute smallest chainring you can fit on a 144 BCD. For the 130mm BCD used by Shimano and many third party cranks for ...


10

By "non-drive" I assume you mean the left side. This is more apt to come loose than the right because of "precession" -- most crank bolts are right-hand thread on both sides, but the motion of the crank arm relative to the shaft tends to loosen the bolt on the left side, whereas it tends to tighten the bolt on the right side. But if this is occurring it's ...


10

The clicking, only under load and always at the same point of the stroke, can be due to: A bad pedal. I've had this a couple of times. The crank arm slipping on the crank. Generally if you've been riding it this way for more than 100 miles or so the crank arm (and possibly the crank) will have been permanently damaged, but tightening the fixing bolt may ...


10

Believe it or not in the range of lengths you are looking at there is very little scientific support for there being any real discernible differences in performance (both in absolute power and metabolic efficiency). For the lengths you are considering I would suggest this is largely a personal preference choice. Crank length and maximal power If we are ...


10

The main distinction is whether the puller is for square taper (and Powerspline) versus Octalink/ISIS. Among square taper crank pullers, there are some older ones made with nutted spindles in mind that don't play nice with the now more common bolt-style ones because their tips are too narrow and can jam into the bolt hole and damage the threads. A couple ...


10

The research on subject (source: Wilson & Papadopoulos: Bicycling Science, MIT Press 2004) shows that crank length has very little effect on pedaling efficiency or or maximum power output. There is a small increase in maximum power output with shorter cranks and and in efficiency with longer cranks, and racers who optimize to the last percent do use ...


10

There is little research on the impact of crank length on power output in cycling. There are some lab studies, and they seem to show that even for crank lengths significantly shorter or longer than the norm, the metabolic cost to maintain a specified speed or power output in the lab doesn't change. Importantly, some of these studies included lengths ranging ...


10

You are undertightening the crank bolts on initial installation. 44Nm or 33 ft-lb work well as generic values for square taper cranks. A basic large beam-type torque wrench works well for crank bolts. If you aren't able to get one, it's safe for basic square taper cranks to reef like mad with something like a 12" ratchet or breaker bar. You'll be ...


10

I would try removing the crank and clamping the pedal in a bench vise. With the pedal pointed downward and held very firmly in the vise, you’d then try to turn the crank clockwise. Otherwise, the specific model of left crank is not essential. You just need it to be a 175 mm Left Hollowtech II crank arm. Some cranks have different q-factors, so you’ll want ...


9

I disagree with the selected answer as most of the provided links are simply opinion without any analytical backing. In terms of choosing a crank length on the basis of performance, there is very little scientific support for there being any real discernible differences widely used crank lengths (160-180 mm). For an overview of some of the scientific ...


9

If you keep the rest of the bike the same a shorter crank gives more ground clearance at the bottom of the stroke, and that's going to be the main thing most people notice. You're unlikely to notice a change in power output unless you're shorter than, say, 1.7m, which would put you firmly on the down-slope of the power curve (ie, the part where longer = less ...


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 ...


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