Cheap chinese MTB handlebars... beware!

[postman]

And condoms and bungee jumping gear.

Crikey how tall is your wardrobe.

 

[Yellow Saddle]

Torqued by hand with a multi tool, so doesn't give much to go on. TBH I go by hand feel rather than Nm, but I can't recall that I've ever sheared a bolt/stripped any threads/crushed a tube in this way before in many years of working on bicycles, tractors, chainsaws and other power tools.

There's your problem right there. Used a multi-tool.

It isn't a matter of stripping anything, but a matter of getting the four bolts up to equal torque and correct. Correct, so you don't strain the bolts or crush the bar and equal, to prevent one bolt from straining more than others and failing prematurely. Remember, a four-bolt stem uses smaller bolts than a 2-bolt stem and are exponentially weaker. Exponentially because of the Pi R Squared rule.

Then, pairing a poorly installed bar with 700mm of lever is looking for trouble.

I also usually assume that all the DB +3D stuff is probably bollocks (if it's even in comprehensible English, not always a given for Chinese sellers) and I don't count grams on any of my bikes. I'd further (erroneously?) assume that cheaper stuff is usually heavier/sturdier than some of the more expensive stuff - seems to be the case on eg Shimano Tourney vs Deore XT (or at least it used to be in the 90s/00s, not sure what the modern stuff's like as don't own any!).

Ironically, this is actually true in this case.

This happens on expensive, branded bars too.

 

[ChrisEyles]

So you'd advocate always using a torque wrench? Always thought they were complete overkill for the tolerances present on a bike (or for people who just can't help gorilla-ing every single bolt as tight as they possibly can).

 

[Drago]

I don't use a multi tool for anything other than road/trailside repairs. They're the tool of the bodger and charlatan, not a valid piece of workshop equipment (unless you're a Halfords bike tech).

 

[ChrisEyles]

Why no love for the multi tool? Surely all that's different is the handle?

I've also got a nicer little mini socket wrench with Allen key bits... But mostly end up using the multi tool as it's in my panniers/rucksack.

 

[fossyant]

I don't use a multi tool for anything other than road/trailside repairs. They're the tool of the bodger and charlatan, not a valid piece of workshop equipment (unless you're a Halfords bike tech).

The only 'multi tool' I used on my bike regular was a set of Park Allen keys that you 'flipped out'. My son's 'borrowed them'... I've gone out and bought some long handled/colour co-ordinated allen keys now he's 'lost' them.

 

[Yellow Saddle]

So you'd advocate always using a torque wrench? Always thought they were complete overkill for the tolerances present on a bike (or for people who just can't help gorilla-ing every single bolt as tight as they possibly can).

No, not always. If you are a very skilled mechanic with lots of experience, then some bolts don't require a torque wrench, especially where the margin of error is huge, such as on BBs and cassette lockrings.
However, on a front loader stem with four 4mm bolts, it is important. It is not about the absolute torque (or tolerances), but the evenness among the bolts, as I attempted to explain earlier on. Further, when the clamp holds a lightweight bar, going over the limit is an added complication, as you've seen.

 

[DRM]

And why not? If demand increases you are suggesting supermarkets won't attempt to meet the increased demand? which they are encouraging by offering deals like Asda's. Delivery Tuesday Wednesday and Thursday for a year £28. They are all offering deals like that. Delivery slots can hardly be increased overnight without training drivers and buying Van's. Do you know at one time they didn't deliver at all?. When they first started delivery do you think they started with the same amount of vehicles and drivers as they have now?

I don't use a multi tool for anything other than road/trailside repairs. They're the tool of the bodger and charlatan, not a valid piece of workshop equipment (unless you're a Halfords bike tech).

Exactly they are ok for emergencies but for a four bolt stem you have to tighten using the cross method, ie top left, bottom right, top right, bottom left, a bit at at time making sure that the gap is even all round from the front plate to the stem itself, torquing it up ensures none of the bolts are over stressed, it’s so easy to strip an aluminium thread

 

[Drago]

Why no love for the multi tool? Surely all that's different is the handle?

I've also got a nicer little mini socket wrench with Allen key bits... But mostly end up using the multi tool as it's in my panniers/rucksack.

You can carve a sunday roast with a swiss army knife, but you wouldn't unless it was an emergency. Then why indulge in similar workshop bodgery?

 

[Vantage]

A multitool is no different to a stand alone tool other than its handle.
The only disadvantage of using one over a normal tool is having to fold in its other tools to switch between them and in some cases, not having the same leverage.
I can and have stripped and rebuilt my own bikes almost entirely with a multitool except in cases where a specialist tool is required (bottom bracket etc).
If one can't do that without royally f**king up the bike, one shouldn't be near a tool at all.

 

[ChrisEyles]

Already use the cross method and torque all bolts as evenly as I can by hand.

Guess my internal torque settings just aren't calibrated for light weight components!

Have to say I'm always very reluctant to work on friends carbon bikes for this reason.

 

[Drago]

Chris, is your real name Bruce Banner, perchance?

 

[ChrisEyles]

Haha, had to Google that, no I'm decidedly stringy

 

[12boy]

You guys have a point....the stress on handlebars has to be severe. I've never had a problem using the same bars for decades but it would sure be horrible to have one fail going downhill at 40 mph. Are non-straight bars such as drop bars, North Roads and bullhorns more or less likely to fail?

 

[ChrisEyles]

Would have thought they're all equally likely to fail at the clamping point - also the wider the bar the more leverage.