Nut dents crank?

The right crank on Het Beest, my Nimbus II Muni, creaked when I was out on the trail and appeared to be somewhat loose. Not having tools with me, I 1-footed home (in fact I 1.2-footed) and then tried to tighten the nut but it seemed rock-tight. With wood and a hammer I nevertheless could hammer the crank further on. I tried again to tighten the nut using even more force, and it suddenly gave way for a small fraction (1/24) of a turn. Shoot, what was that?

I undid the nut completely to check the threads etc, and found out that the nut which has anti-loosen dents on the underside, had deformed the crank face it has been pressing against for at least half a year. (The crank should be flat there, shouldn’t it?) I tightened the nut once more, and the last bit went in 1/24 turn increments. I’m not sure if the nut is fully tight, but I can’t overcome any more bumps. Nor do I know if the loose crank is cured well, haven’t ridden Het Beest since. Pogosticking in the garage alternating with both feet forward, it looked OK. The crank is a Bicycle Euro 170 mm, the nut may be the one that came on the Nimbus II or I may have swapped it.

Does this problem sound familiar to anyone?

The pic shows the crank face and the underside of the nut. I haven’t checked the other crank.

Klaas Bil

crank_and_nut.jpg

Cool. Auto-ratcheting. I don’t remember taking off steel cranks but if the serated nut is harder, as it obviously is in your case, then it’s no surprise that the crank face will be deformed like that. All that deformation gets sheered off of aluminum cranks when I remove the nut because it’s so soft.

I think your results are normal. Sounds like your crank is good and tight!

With alloy cranks, you tend to get more of the aluminum “scraping off” onto the underside of the nut.

I’ve long felt that those serations on the back side of crank nuts do more harm than good. Of course, the idea of the serations is to act as a kind of ratchet and prevent the nut from loosening. Maybe they DO help to keep the nut from loosening on steel cranks (unlikely IMHO) but they chew up aluminum cranks. I think the serations just add resistance when tightening the nut - thus preventing the nut from adequately pushing the crank on to the taper. I’ve even gone so far as machine off the serations.

The only real solution is to use the crank installation recipe that John Childs has written about many times.

Steve Howard

Re: Nut dents crank?

On Wed, 14 Jan 2004 21:52:08 -0600, showard
<showard@NoEmail.Message.Poster.at.Unicyclist.com> wrote:

>The only real solution is to use the crank installation recipe that John
>Childs has written about many times.

If I remember correctly, it focuses on hammering the cranks on rather
than tightening the nut to get them on? That’s basically what I do.

Klaas Bil - Newsgroup Addict

I have a feeling you might need two points of contact with the ground for such a thing to work? Or at least training wheels on the front and rear. - John Foss commenting on a picture of a one-wheeled vehicle he saw on RSU.

Re: Nut dents crank?

Confess, Klaas; you did not feel that it was 1/24 of a turn, but you counted the dents :wink:

But even if the nut marked the crank: Shouldn’t the crank stay where it is when properly hammered on? Hm.

Regards,
Juergen

Re: Re: Nut dents crank?

Put grease on the taper. Use a big C-clamp (bar clamp) named Bessey to press the cranks on. Then use red Loctite on the retaining nut threads.

The Loctite is the important bit. I would suspect that with the Loctite you could file off the scallops on the retaining nut. The Loctite would keep the retaining nut from working loose. That would keep the scallops from digging in to the crank like that.

i like the feeling you get from those on a steel crank arm while torquing down that final time.

thump thump thump…

Re: Re: Nut dents crank?

Of course. In fact, “as soon as” the wrench lost its ‘resistance’, I stopped pushing it so it felt almost the same as if the wrench had slipped on the nut (which is 1/6 turn).

No, the hammering on puts the crank at the right position, but the nut is supposed to keep it there. However, if the dents on nut and crank are too high, the tops of the nut will be in the valleys of the crank. And that may not be tight enough.

Re: Re: Re: Nut dents crank?

Of course, how could I forget? A recipe by John Childs always contains loctite, just as some other people’s recipes always contain pepper (or something else). :slight_smile:

Loctite, a universal spice…

Re: Nut dents crank?

170s in the Netherlands? Pulling a trailer?

Re: Nut dents crank?

On Thu, 15 Jan 2004 19:05:17 -0600, cjd
<cjd@NoEmail.Message.Poster.at.Unicyclist.com> wrote:

>170s in the Netherlands? Pulling a trailer?

Some of the grades on the MTB trails near my house are over 30%. I
love torque. Speed on the MUni is hardly relevant for me.

Klaas Bil - Newsgroup Addict

I have a feeling you might need two points of contact with the ground for such a thing to work? Or at least training wheels on the front and rear. - John Foss commenting on a picture of a one-wheeled vehicle he saw on RSU.