Current Projects chat and miscellany

That happened to me once in London traffic, not ideal!

Since then I always use a bit of blue loctite on the tapers, works well and have no trouble taking the crank arms off.

frames with italian thread require bottom brackets with 70mm shell width but will it make any difference if i get a bb with 68mm shell width?

There's much more to it than shell width. Italian threads are different diameter from BSC, and on the drive side even a different hand.

I always use a bit of blue loctite on the tapers, works well and have no trouble taking the crank arms off

You'd have even less trouble if you used a spot of grease on the tapers, and if you do that and torque the crank bolt correctly they don't loosen.

ok, thanks, so hopefully crank hole edges aren't worn

always wisdom, thanks!
will grease up and tighten!

chrome duffle bag recommended...

I've got a prologic tackle bag which is a perfect fit between the drops, just need to figure the best way to secure it, may get some restrap magnets fitted.

badass beetle ftw

You're right the issue was lack of torque, I have since bought a torque wrench.

The loctite is probably slight overkill but gives me peace of mind ;)

The loctite is probably slight overkill

It's not overkill, it's just plain wrong. The grease isn't there to make disassembly easier, it's there to make the assembly correct in the first place. Bolt torque gets converted into bolt tension, which converts to axial load on the crank, which pushes it up the inclined plane of the taper. There's a lot of friction on an inclined plane, and it's only by lubricating it that you can turn that push on the crank into the right amount of distance up the hill to create sufficient strain in the crank boss, which generates the hoop stress which provides the resistance to loosening by applying radial load at the interface. If the initial hoop stress is too low, the pressure between axle and crank will drop to zero on the low side when you start pedalling, and that's what lets the crank fall down the hill. Once that starts, it's then looser on the next turn and things start to fail catastrophically. A square taper is a pretty awful design, which is why you'd never see one on a machine designed after the invention of spline broaching tools except on a bicycle where legacy designs from the Victorian era remain current. Despite the problems, you can make a square taper into a reasonably reliable crank attachment if you understand the physics and give the kit its best chance of working.

Don't get me wrong I don't want to advise people to not use grease. Apart from that particular set of cranks I have always used grease, and I know there are a lot of people online and even in bike shops saying that you shouldn't use grease when installing square taper cranks, which results, as you rightly mentioned, in the crank not being pushed far enough up the taper.
However I was under the impression (and this is only from observation) that the Loctite would provide enough initial lubrication for installing the cranks correctly before it becomes solid. Anyways I shall use grease from now on and thanks for the explanation

Loctite would provide enough initial lubrication for installing the cranks correctly before it becomes solid

In terms of lubricity, it's certainly better than dry assembly, but something whose sole purpose is lubrication is always going to be better.

Which Prologic bag? Do you have a link?

I've had this happen, once with square taper and once with gxp.

I should probably buy a torque wrench.

ky?

ky

OK for lubrication (water is actually a really good lubricant), not so good for corrosion prevention.

i've had it a few times on low end shit mate, managed to sort it hopefully today, I used copper grease on the axle, and following the befamed 'tester's advice, tightened crank bolt up as much as i dared, just done about 18 miles on it, so Jah willing, all will be good

In other news, bit worried I may not find an expanding seat bolt clamp for me pista build, think I'll hold fire on any other parts purchases till i sort it

such a comfy set up

Do you like camo?

such a fun comfy set up right now

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How long are your arms?!?!?!

Rear wheel needs matching tire!

Beetle own the street