I read somewhere here that the bolt needs to be real tight around 40 Nm, someone suggested standing on a hex key to get it about right.
After the initial hand tightening a few days later I tried that, only to find I could go on and on tightening it this way so I stopped before I presumably either split my crank arm or sheared the bolt..
The torque is AFAIK radius x N = 0.16 m x 9.81 m/s^2 x 85 kg = 133 Nm. A bit much isn't it?
No idea about the maths, but i wouldn't dream of attempting to use my body weight to tighten that bolt. Sure it needs to be tight but i've never had one come loose and have only ever hand tightened them.
Square taper always needed a check a ride or two later but still only went to limit of strength with an 8" lever. Never needed to stand on it.
Next thought, to grease the taper or not?
I barely do mine up past nipped and they haven't come off.
40Nm is normally the toque for a cassette lock ring isn't it? Another spec that gets roundly ignored.
Standing on tools is removal only in my book. With the exception on car wheels at the side of the road.
If I remember correctly 25nm was the max I ever went to, that was with shinano, fsa, raceface, middleburn and topline cranks, never had one come loose.
Little bit of grease rubbed between finger n thumb then smear on taper leaving a film of grease.
Generally the size of the tool roughly dictates the maximum torque you can apply by hand. Standing on them violates that 😉 So standing on a 0.16m Allan key with 700N is huge overkill. Did you put all your weight on it? If you were still on one foot then you probably put less than half through it, say 350N with a torque of 56Nm which sounds better.
Never had a problem with the full size Park Allan keys but have never needed to stand on one either.
It's a bit high but some cranks can take it. I ride a unicycle and that puts huge forces on the cranks. These days they are usually splined but they used to be square taper. You had to really monster them up to stop them coming loose. It was possible to split the crank though if you over did it, but that was rare
Standing on tools is removal only in my book. With the exception on car wheels at the side of the road.
Indeed..
Generally the size of the tool roughly dictates the maximum torque you can apply by hand. Standing on them violates that 😉 So standing on a 0.16m Allan key with 700N is huge overkill. Did you put all your weight on it? If you were still on one foot then you probably put less than half through it, say 350N with a torque of 56Nm which sounds better.
Never had a problem with the full size Park Allan keys but have never needed to stand on one either.
Yes almost all as I stood on it, perhaps more realistically 60 kg worth so 94 Nm, I could just keep going so I stopped - hopefully in time to prevent the crank arm hole from getting permanently dilated lol.
But also bear in mind that's only correct when the Allen key is exactly horizontal. As it rotates the effective torque decreases as it is not aligned so clearly with the gravitational pull.
Speaking of square taper bolts does anyone know where to get a thin wall socket to fit a hex crank bolt (as opposed to allen headed)?
Do you need thin wall? Can't say I can ever recall a socket not fitting. If you do have particularly thick sockets, maybe impact sockets, then try another brand, particularly a cheap one as they often have less metal
It's a quite ancient Kamasa set. Maybe newer ones are thinner. I suppose if I take my socket into Halfords or similar I could do a comparison. Or just ride my bike down the aisle and check one!
Box spanner or you do get thin ones.
Although to be honest normal socket has always worked for me.
Crank removal tool has flats on the side to use a spanner on. Never used a socket on square tapered bb.
I always do mine up FT. If they come lose, then the taper in the crank gets damaged and they'll never be right again. I do it up with a hex bolt then replace with the Allen bolt, for no other reason than it looks nice.
99 middle burn rs7 xc duo still in weekly use, fyi.
Usual torque for Shimano square taper is 29 lbs/ft which I think equates to just over 39 N/m? Yes, unless you’re after the retro look of plastic covers over a hex bolt replace with a nice Allen bolt - easier to tighten and repair on the trail - if you don’t torque properly..
Original square taper crank pullers should be able to undo the bolt as it has a built in socket. Modern pullers don’t have this luxury.
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