What bolts would you not replace with alloy?

I’ve decided to replace a lot of the steel or stainless bolts on one of my bikes in an effort to hit a weight point. Where wouldn’t you do this. Current list of locations I’m looking at change are;

Brakes, lever clamp bolts (x4)
Brakes, calliper mount bolts (x4)
Brakes, disc bolts (x12)
Stem, face plate (x4)
Stem, steerer clamp (x2)
Chainring bolts (x8)

I’ll be using a torque wrench to avoid mashing the alloy.

disc mounts
Caliper mounts
chainring
Steerer clamp
Faceplate
Use TI for these

Stainless steel is an alloy.

What Teej says apart from chainring bolts. Many chainsets come with aluminium bolts as stock

I fitted alu bolts to my brake calliper mounts – but only the ones in compression… 😯

Anything that invloves substantive shear or tension forces I’d not go near with alu though.

My experience of aluminium ALLOY bolts is they’re too soft to use on anything safty critical. Which rules out (for me anyway) brakes and steering related bits.
At a push I’d use them as chainring bolts and possibly shifters clamps.
At TJ says Ti may be a better option, but them you’ll have issues with them galling unless you use the correct assembly paste.
I’d stick with steel and have a good log chopping session before riding.

Just go for a poo. It’s far more cost effective (and or lose some weight generally).

Why do people always say “have a poo” etc?

Do you not think that people with light bikes might just have worked it out for themselves?

Hmm, was expecting a few of those to be no goes but not that many. Don’t think I want to splash out to Ti so maybe a bad plan! I’ve got the assembly paste already (as have to use that between Alloy and steel on my car).

😀 bikes not even that light, 27lbs at the moment, I just want to get it under a certain weight (yes I know) without compromising certain bits (i.e I don’t want to use normal grips instead of lock ons).

All of them, there is likely to be a cheaper way of saving the weight.

Yes:
Stem steerer end
Brake levers
shifters
chain rings
Brake calipers if in compressin

No:
Stem face plate
Brake calipers if in tension

So do lever clamps, (even in brake levers failure will not be catestrophic I would have thought) bottle cage mounts, light brackets, brake reservoir cap bolt, front mech clamp bolt, that sort of thing

So do lever clamps, (even in brake levers failure will not be catestrophic I would have thought) bottle cage mounts, light brackets, brake reservoir cap bolt, front mech clamp bolt, that sort of thing

Very true. I tend to have levers done so they rotate under undue force anyway so that would probably mean these bolts would not end up under a lot of stress.

Could use 3 steel bolts instead of 6 in each disc. Loctite them in with a high grade and check regularly, sure a lot of the pro’s do it.

Stem steerer end
calipers if in compressin

I wouldn’t…and what bolt is ever in compression?

brake reservoir cap bolt

M3 x 8mm or so…how much weight wil lthat save

TJ – failure of brake lever clamps “not catastrophic”? You’ll be advocating home-made carbon fibre caliper mounts next! 😛

none of them the weight saved v risk makes it not worth it IMHO
Seriously how much do you expect to save doing this? a few grams max surely.

I once fitted alloy bolts to my front v-brakes. I’m lucky I still have teeth, as they snapped the first time I braked hard.

none…..

Why do people always say “have a poo” etc?

Because it’s cost effective and safer. Come on, everyone knows that.

Do you not think that people with light bikes might just have worked it out for themselves?

No, of course not.

Look at all the people with 20% body fat buying carbon road bikes thinking it will make them climbing gods.

I wouldn’t…and what bolt is ever in compression?

Front post mount caliper bolts?

Ashima do alu rotor bolts, they’re a bit soft, but they’re designed to be rotor bolts, so I figure they’ll be fine!

I’d not use alu in stem, seatpost, seat clamp and it’s probably not that sensible in calipers (although I’d certainly do it). Everywhere else they’re fine, so everything in your mechs, shifters, brake levers, chain rings, bottle cage, headset top cap etc. In fact, get one of the Mt Zoom one piece top cap and bolt, cheap, neat, and saves a chunk of weight over a normal bolt/top cap.

On the other hand, if your bike is 27lbs, changing all those bolts may get you 80g or so, which isn’t really much, so I’d look elsewhere first, unless the bike’s an 8″ travel DH bike.

However.

Bolt correctly fastened can only ever be in tension. Even if the joint is in shear the bolt is in tension and the shear forces are resisted by the friction between the surfaces. otherwise the bolts fret and wear.

Why bother first bit of mud you hit will add the weight you have taken off.Why do people get so anal about a few grams?

Because it adds up. And adding 100g to a lighter bike still makes it lighter than the equivalent heavy bike.

Allowing for ‘alloy’ = aluminium I’d go with none too.
Might be ok for bottle cages (apart from the slight risk of bi-metal corrosion of course).

I go the other way, and swap as many bolts as possible for decent stainless. Ti bolts make me feel queasy doing them up, so I now don’t use them (and that’s with suitable lubrication and a torque wrench).

You are right, it does all add up, but I’m a slow old tourist now, so I’m not tremendously concerned about shaving the weight right down, especially in exchange for resilience (and I’m certainly not shaving!).

Bolt correctly fastened can only ever be in tension.

Yes absolutely, in fact, correct tension is critical for the bolt to remain fastened securely.

There are, however, the additional forces exerted by the brake when its actuated. I’m thinking specifically post mount here – The pad contact area on the disc becomes a ‘pivot centre’ and the caliper will attempt to rotate around this centre, resulting in increased tension in one boltas it tried to rotate away from the post/adaptor, whilst the other part of the caliper will be pushed into the post/adaptor. This means I can change one bolt, since the increased compressive load puts little extra stress through the bolt.

I’ve probably explained that fairly badly.

Theres no way I’d use an alu bolt in any application where it sees appreciable tension or shear beyond that required to fix it securely – its not worth the risk.

Why bother first bit of mud you hit will add the weight you have taken off.Why do people get so anal about a few grams?

Sommat to do isn’t it? Alu bolts are pretty cheap anyway.