27 votes

Is it bad for the bike to pedal backwards?

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 ...
whatsisname's user avatar
  • 12.1k
25 votes
Accepted

Plastic ring on new Shimano crankset, toss or keep?

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 ...
Móż's user avatar
  • 23.3k
24 votes

Stuck pedal, I've tried everything

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 ...
Criggie's user avatar
  • 121k
21 votes
Accepted

Why does a loose pedal destroy the crank threads?

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 ...
Argenti Apparatus's user avatar
19 votes
Accepted

Should square taper cranks be greased before installation?

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 ...
Nathan Knutson's user avatar
18 votes

Does the saddle height need to be changed when the crank length changes?

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 ...
Nathan Knutson's user avatar
15 votes

Would variable crank arm length be beneficial to a rider?

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 ...
David Richerby's user avatar
15 votes
Accepted

What type of crank fitting is this?

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 ...
ojs's user avatar
  • 21.8k
15 votes
Accepted

Broken bottom bracket?

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 ...
Argenti Apparatus's user avatar
14 votes
Accepted

What tool do I need for this bolt that holds the crank arm on this stationary bike?

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: ...
abdnChap's user avatar
  • 3,324
13 votes

What are the advantages and disadvantages of the different chainset designs?

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,...
thelawnet's user avatar
  • 4,170
13 votes

Crank-arm fell off *after lube*

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 ...
whatsisname's user avatar
  • 12.1k
13 votes

Does crank length affect the number of gears a bicycle needs?

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 ...
Adam Rice's user avatar
  • 29.2k
12 votes

39-53t chainring on full suspension bike

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 ...
Andy P's user avatar
  • 18.3k
12 votes

Fuji bolt fell out please help!

The crank appears to be a cottered crank and hence the missing part is a cotter pin. See the article by Sheldon Brown about cottered cranks https://www.sheldonbrown.com/cotters.html These parts can be ...
Vladimir F Героям слава's user avatar
11 votes

What if both wheels were powered by pedalling?

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 ...
Móż's user avatar
  • 23.3k
11 votes
Accepted

What are the advantages and disadvantages of the different chainset designs?

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 ...
Weiwen Ng's user avatar
  • 29.7k
11 votes

Stuck pedal, I've tried everything

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 ...
Pisco's user avatar
  • 783
11 votes
Accepted

Are the chainrings supposed to have irregular sized teeth?

Yes, modern chainrings have teeth that vary from each other. They are formed that way to enhance shifting between the different chainrings. Older chainrings from a couple of decades ago had teeth ...
Ted Hohl's user avatar
  • 6,089
11 votes

Removing a pedal that has skipped a thread

The most likely cause of what happened is the pedal was installed with insufficient torque. This can allow movement in the threads that degrades the crank threads, which are aluminum in most cases and ...
Nathan Knutson's user avatar
10 votes

What is "crank preload"

Good question. This is a term that is frequently referred to but not clearly defined. I added a definition of preload to the terminology index under the bearings page. Consider your crankset. Preload ...
Weiwen Ng's user avatar
  • 29.7k
10 votes

Disassembling crank on a 2006 Trek Pilot 2.1

I had this exact issue come up at work today, with the same crank. It was quite frustrating! Unlike the OP, I tried progressively harder hammer smacks early on. And also unlike the OP, I was unable ...
Nathan Knutson's user avatar
10 votes
Accepted

Do crank arm pullers vary in sizes or there is just one size?

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 ...
Nathan Knutson's user avatar
10 votes

Would variable crank arm length be beneficial to a rider?

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 ...
ojs's user avatar
  • 21.8k
10 votes

Shorter crankset on road bike

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 ...
Weiwen Ng's user avatar
  • 29.7k
10 votes
Accepted

How to keep square taper cranks tight?

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. ...
Nathan Knutson's user avatar
10 votes
Accepted

Do forged alloy crank arms suffer from age-related fatigue?

Aluminum has no fatigue limit and thus it is impossible to make an aluminum bike part that won't fail with enough use. Fatigue accumulates with load, not time. Good forged cranks with designs that ...
Nathan Knutson's user avatar
10 votes

Can I update a decade-old mountain bike to modern standards?

A large 11-speed cassette with 26" rear wheel is tricky. The derailleur arm is very long in comparison to the wheel and the ground clearance is quite poor. But a good news is that usual hubs are ...
Vladimir F Героям слава's user avatar
10 votes

Can I update a decade-old mountain bike to modern standards?

Despite the massive moves and designed obsolesce, with marketing and social media driving all the hype over the latest and greatest next best thing, the parts to maintain the bike are readily ...
mattnz's user avatar
  • 49.1k
9 votes
Accepted

Are the Truvativ powerspline BBs reliable?

The TruVative power spline BB is a decent, if inexpensive design, and is unlikely to have failed through a design fault. All bikes, regardless of price or quality level, require periodic maintenance....
zenbike's user avatar
  • 29.9k

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