Why do bikes need Allen keys?

[Mom]

Answer to your first question...phuck nose.

More robust methinks..less able to round out under pressure.........if I was smart enough to comment from an engineering perpective it is probably something to do with even pressure being applied to wider surfaces, avoiding the whole..........GRRRRRRRRRR F#@K me now I have to drill it out thang happening.......

[Motu]

Nothing to do with them rounding off when being dismantled....they make bikes to be assembled quickly,not to be pulled apart.Phillips head screws were used for several decades...the change has come from consumer demand.Allen screws look cool because the racers use them,hence production race rep bikes got them...now they all have them.Like airconditioning or power windows in cars - you never saw them 20 years ago,now every car has it.

[Animal]

Hey Bert,

Unless you buy cheap, nasty, evil shit tools, the metal used is is always heat-treated / processed to be a helluva lot harder than the nuts or bolts they're undoing. If the Allen key suddenly becomes rounded because the hardness if the bolt exceeds the hardness of the Allen key, you should give yourself a healthy kick in the arse for buying crap tools. If the jaws of a spanner you're using to undo a hex bolt suddenly spread open like a Hillbrow whore, the same applies: Crap tools vs hardened steel bolts. Unlike spanners, which need a large turning arc to undo the subject bolt, an Allen key - especially those with a square drive socket base - require very little turning arc, and you don't run the risk of demolishing your knuckles on adjacent bike parts. I don't think I've answered your question but it was a helluva lot of fun trying to!

[krash]

Hey man, Coastal fasteners are on abel smith st in wellington. Can't go wrong.

[moko]

...the change has come from consumer demand.Allen screws look cool because the racers use them,hence production race rep bikes got them...now they all have them.

Hit the nail on the head with that one.There was a time when accessory sellers were making a fortune selling Allen bolts to replace the invariably poor quality fasteners fitted as standard to bikes.Be grateful,just about any job on any bike was made twice as hard as it should be because of crappy bolt heads rounding off and it was pretty standard practice to get replacement Phillips screws before you started any job where you`d come across them,biggest mystery was always how the Japs got them to tighten in the first place because no matter how careful you`d inevitably trash the bloody things getting them out.

[Pixie]

Hit the nail on the head with that one.There was a time when accessory sellers were making a fortune selling Allen bolts to replace the invariably poor quality fasteners fitted as standard to bikes.Be grateful,just about any job on any bike was made twice as hard as it should be because of crappy bolt heads rounding off and it was pretty standard practice to get replacement Phillips screws before you started any job where you`d come across them,biggest mystery was always how the Japs got them to tighten in the first place because no matter how careful you`d inevitably trash the bloody things getting them out.

The Phillips screws weren't poor quality.
The "mechanics" that use the wrong sized driver or pozidrive drivers on them were the ones responsible for buggering the heads.

[Ixion]

Not entirely. The screws were tightened at the factory using air operated equipment. Often they were very tight (and I believe tended to tighten up in use, too).

Removing them with an ordinary Phillips screwdriver could be very difficult. The design of the Phillips screw is such that , unless a considerable axial force is maintained, the driver , with its angled tips, will tend to "cam" up the slots in the screw. Once that happens the resulting damage to the head makes removal very difficult.

I never had any problems, using an impact driver. But not everyone has one

The Allen head, having no angled faces does not have this problem.

[TLDV8]

Ducati V-Twins have used capscrews as standard since 1971,maybe the singles going back to the 1960's also.
The phillips head screws used on japanese bikes in the 1970's were made of cheese,if they were anything like tight they were not going to be removed with anything short of an impact driver,not to mention secondhand bikes and previous owners backyard mechanic's.You can actually torque a capscrew with ease which is half the problem solved.
The force applied to a capscrew is direct to the rotation unlike a cheesey screw.
Capscrew's are available from any Engineering supplies outlet or fastener retailer.As close as the Yellow Pages or an a'Courts Business Handbook.
As far as Allen Key's (imho) you get what you pay for,buy a quality set and they will last the distance.Home use,that could be decades.

[HenryDorsetCase]

Hit the nail on the head with that one.There was a time when accessory sellers were making a fortune selling Allen bolts to replace the invariably poor quality fasteners fitted as standard to bikes.Be grateful,just about any job on any bike was made twice as hard as it should be because of crappy bolt heads rounding off and it was pretty standard practice to get replacement Phillips screws before you started any job where you`d come across them,biggest mystery was always how the Japs got them to tighten in the first place because no matter how careful you`d inevitably trash the bloody things getting them out.

absolutely! one of the first tools I bought was an impact driver so I could get shitty Philips screws out of old Jap bikes. My CB400 still had them, and Ive bought replacements (mmmm polished, pity the cases carry their 30 year "patina"). Back to the old standard WD40, impact driver and a 3 pound hammer. I used to get completely livid when a ten minute job turned into an epic because I had rounded off a phillips screw.

You get handy with drills and ezy outs and stuff like that though......

[HenryDorsetCase]

oh yeah, one of those little magnetic trays is useful. I have a roller stool with a a tray under it as well for collecting bits and bobs.

and Im pretty sure the tradezone Xmas catalogue had long handle quality allen keys (with ball ends too) for reasonable money... about $30??

[ManDownUnder]

Allen keys are made of high tensile steel (i.e. they're damned strong) and their head design is small, relatively discreet and can easily be recessed into things - drill a whole the same diameter as the allen key head and you're good to go.

Try doing that with a hex head bolt... high tensile or not.

[Motu]

Which comes down to ''it looks cool'',and that's why production bikes have allen head fasteners.

[Brian d marge]

The head on an allen screw is smaller . ie smaller area , so the forces are distributed over a smaller area , not good

Thats why the washers ( head design ) are built into the factorybolts , load spread , espesially when used with High silicon castin alloy , and a stack of other desighn concideration ,,, sorry bit rushed so crap answer ,,, but given choice I use the factory bolts ,,,except where a protrusion could hurt someone in case ocf a crash ..eg top yoke

Stephen

[froggyfrenchman]

Cap screws are made of high tensile steel (the same grade as average brands allen keys) so you do really need good allen keys. One of the major attractions of capscrews is the thread is cut right up to the head there is no "blank" section of flank.

Remember when buying capscrews for your bike, the anodised coloured ones may look pretty, but you can only anodise alloy, so they have roughly the same tensile strength of old cheese. Be gentle tightening these and only use for decorative purposes where no strength is needed!

Just 2c from an biker/engineer.

For the record, almost every bolt on my bike and any machinery i build is a cap screw. They are better in all the ways listed by everyone in this thread

[Crasherfromwayback]

Not entirely. The screws were tightened at the factory using air operated equipment. Often they were very tight (and I believe tended to tighten up in use, too).

Removing them with an ordinary Phillips screwdriver could be very difficult. The design of the Phillips screw is such that , unless a considerable axial force is maintained, the driver , with its angled tips, will tend to "cam" up the slots in the screw. Once that happens the resulting damage to the head makes removal very difficult.

I never had any problems, using an impact driver. But not everyone has one

The Allen head, having no angled faces does not have this problem.

Maybe why 'posi-drive' was sometimes used? They're a bit 'flatter' in the bottom of the grove no?? One problem I don't think anyone has mentioned with allen head bolts is I feel......it's way too easy to over tighten things if you're heavy handed....which can cause real serious problems!!