Max Torque on Suzue threads

Having a suzue hub with one good side is useless, so I did a test. I took a stock steel crank (alread twisted, so useless) and tried to see how much torque I could put on it before the threads gave out.

85-90 pounds.

Not that anyone should actually tighten them this tight (I could see some damge to the tapers or cranks happening) just some FYI

Re: Max Torque on Suzue threads

This would be considerably more meaningful if we knew whether it was inch-pounds, foot-pounds, yard-pounds, dog-pounds, or just some random Sofa unit.

Latest is I’ll be in Ontario Mon 23 Feb to Sun 29 Feb. Could change again. Arrival date will remain the same, departure date may move later.

Those are Sofa pounds, which after a quick check on the measurement convertor has those equal to foot pounds.

I’m travelling to North Bay on the 29th, if your date is extended we can hook up. (I’ll even go to Sudbury to see ya!..but I’ll still owe you 10 hours :slight_smile: )

Cool experiment, Sofa. Thanks!

Great test! Darren told me 40 ft-lbs awhile ago, looks like there’s lots of margin to failure (at least for the hub threads) in that number.

Thanks for the peace of mind!

Was that lubricated Sofa please?
How did it fail:
Strip hub threads
Strip nut threads
Bit of both


I think Darren’s max 40 is saying you should only use a max of 40.

there was no grease, and it was the threads of the suzue that got ruined.

The still perfect nut went right back in the tool box after threading onto another spindle for testing

Re: Max Torque on Suzue threads

On Fri, 6 Feb 2004 14:16:08 -0600, dazedNcontused
<> wrote:

>Great test! Darren told me 40 ft-lbs awhile ago, looks like there’s
>lots of margin to failure (at least for the hub threads) in that

I’m not sure that 40 ft-lbs max leaves a lot of margin. Doesn’t riding
put all kinds of forces on the crank including sideways forces which
would transfer to the hub threads? Or would one assume that if the
crank is on OK, all those stresses are taken up by the square tapers?

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: Re: Max Torque on Suzue threads

It would be difficult to answer that question directly without some sort of expensive study. However, I started with 35 ft-lbs as an increase from the standard bike torque of about 25 ft-lbs, then increased from there after about a year. I have never had a problem with 40 ft-lbs, on many different personal and customer unis now, provided that I keep a close watch on the cranks. I check them before every ride and redo them if there’s any doubt in my mind about the connection. So it works in practice. People don’t strip hub threads by riding, but by honking down with big wrenches in order to make it “really tight”.

Re: Re: Max Torque on Suzue threads

I think the maximum stress in a threaded fastener typically happens during installation. At that point you have the forces of the threads pushing against each other combined with the forces of the threads rubbing against each other. Once it’s on, you should be fine. And yes, the square tapers should take all the bending and torque loads from the cranks.

Re: Re: Re: Max Torque on Suzue threads

Probably the more so in my own Suzue. Recently, I posted a picture of my self-ratcheted (SP?) cranks. I have to overcome a ‘stress hill’ when tightening the nuts, but once installed they sit in a ‘stress valley’.

Klaas Bil