hybridbkrdr

So I decided to do things on my own but do not have a torque wrench. In any case, when the bottom bracket was installed, I used as much force as I could (as per a youtube video I saw). On the (square taper) crank bolt, I didn't want to strip it so I used just enough force. I thought it was enough but one day one side started wobbling. So I tightened it again and it stayed for a while until it started creaking. I put a reasonable amount of force this time (I think).
Now, the question. Will this continue to occur after this happens once and do I have to ask a shop to use Locktite?

trailangel

After the initial tightening of the crank bolt, did you re-tighten after 20 miles or so? You are supposed to.
Some instructions here:
https://www.renehersecycles.com/wp-c...2016_03web.pdf

Threadlocker can be used instead of grease on the threads.

Possibly you have ruined the crank arm by riding it loose.

ThermionicScott 

Just buy a damn $20 torque wrench.

Jeff Wills

That bolt requires 300 to 400 inch-pounds of torque... which is a crap-ton if you're using an ordinary socket and ratchet wrench: https://www.parktool.com/blog/repair-help/

Once a crankarm works loose, the tapers where it mates to the spindle are distorted and there's no good way to fix them. Replacing the crankarm is the only correct repair.

I've been working on bikes for 40+ years. I've never seen a crank bolt strip, but I have seen lots of crankarms ruined by insufficient torque.

Trevtassie

I had a new one on my ATS Speed Drive... the washers under the bolt heads dished while I was on tour (I discovered when I got home). Cranks kept coming loose, tighten up, come loose. Fitted properly originally, re-torqued etc etc. Pulled them off when I got home and discovered the washers were made of flattened out beer cans. Because they dished they distorted the crank taper , so it became a bit of a self reinforcing problem, since the distortion was stopping the taper from properly seating. Anyway, hopefully I've fixed the problem with a high tensile washer under the bolt head and a clean up inside the crank..
You can see where the dished washer distorted the top of the taper.


Old washer, really soft and small in OD. The new one fits neatly in the crank, so should spread the load away from the edges of the taper.


New washer is much thicker and is stronger steel as well.

Andrew R Stewart 

Can't say I have ever seen a crank bolt washer as thin as a beer can... Andy

davidad

https://www.sheldonbrown.com/brandt/...ng-cranks.html

ThermionicScott 

Your bolt looks like it has a washer built in to the head -- why bother using anything extra? I never do.

phughes

No it's not, it's only 33.3 foot pounds at 400 inch-pounds. That is not, "a crap-ton." That is very easy to exceed without a torque wrench, so it is not difficult to achieve with a socket and ratchet.

hybridbkrdr

I have two bike builds, one mountain bike and one flat-bar road bike that are fine. The mountain bike has Shimano Alivio square taper cranks (Niagaracycle) and Stronglight bottom bracket (got from xxcycle in France). The flat-bar road bike has Shimano Sora square taper cranks (Chainreactioncycles) and Shimano BB-UN55 bottom bracket (Niagaracycle). So, if I apply force sideways on both bikes, there's no play.

However, for my winter bike, I chose to install a Suntour bottom bracket and Suntour cranks. I have the feeling the cranks are on solid now but the spindle seems to have a little bit of play in it. Is this normal for a Suntour bottom bracket?

San Rensho 

And oil the tapers of the spindle. Then the arms will grab the spindle harder and the arms will be much easier to remove.

Bike Gremlin

I use anti-seize (mounting paste) on the axle, bolt threads and face of the bolt (part that pushes against the crank).
That way I'm certain that when tightening, it slid all the way it should and that proper preload was achieved.

Never had one come loose installing them that way and they are fairly easy to get off afterwards.

Grease to should do the job, though, for mounting stuff, I prefer the mounting paste.

Trevtassie

Ummm, because the washer was separate from the bolt and it dished so badly it damaged the crank? There's even a picture of one of the washers with the bolt head impression in it. Those bolts are needed because they are drilled for the shifting mechanism shaft. I could have drilled some shouldered bolts, but putting a high tensile washer on the already drilled bolt seemed easier.

ThermionicScott 

My bad, I thought the bolt heads had built-in washers and additional washers were being used. Your new washers look up to the job.

trailangel

I must really be... behind. WTH is a "shifting mechanism shaft"?

Trevtassie

For these: Welcome to ATS
Not a bad jigger actually, so far after my first tour, apart from the #$%^ cranks coming loose constantly. Comes out about 200g heavier than having a double chainring and shifters. Mostly I run it in 1:1 with a Rohloff. When I'm coming down hills I bump it into high gear and go like hell, the Rohloff runs out of gears too soon for my liking otherwise. It makes a bit of racket in high gear, which will quieten down a bit hopefully once it's worn in.

Zinger

Check it for looseness every ride thereafter for a few but back off your torque on those a little so you don't hob your crank tapers and pull the cranks too much towards the frame.

When I tried that without a torque wrench I wound up having to shim 2 sides, 90 degrees apart, of each side of the internal crankset tapers with spark plug gap gage material matching in thickness on each individual side of the bike...

So torque wrenches in your workplace, like tire boots and chain breakers on rides, are very occasionally more than just handy.

Wilfred Laurier

Hard to be 100% certain from the blurry pic, but I think the taper on that crank arm is fornicated. Either from riding while loose or from overtightening. Find a replacement left crank and throw that one in the trash.

As for the washer, generally when you have a crank bolt with a flanged head like the one shown you do not use a washer.

Dan Burkhart 

I will go out on a limb and guess a Schlumpf drive is involved