[Closed] $99 Forged Carbon Crank

Interesting idea. Effectively like fibreglass but with carbon fibre.

What could go wrong?

Looking at the unpainted part implies that this is an uglier (IMHO) alternative to Campag carbon cranks. Might be cheaper of course...

Indiegogo? I'm out.

You can buy traditionally made carbon fibre cranks from china on ebay for £99 that weigh about 440g with a 104bcd spider and standard shimano axle.

Looking at the unpainted part implies that this is an uglier (IMHO) alternative to Campag carbon cranks. Might be cheaper of course...

I was going to say, looks like my older FSA cranks too.

However I take issue with uglier, nothing it uglier than Campags recent chainsets, even Shimano!

What's up with indiegogo njee?

njee20 - Member
Indiegogo? I'm out.

Not to mention "#recumbant"

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Quite. It's brown M&Ms all over again.

They don't know what forging means? I'm out.

I'm not totally up to speed on "Forged Carbon" but I was given to understand it's not actually all that great at producing [i]strong[/i] components when compared with regular laminated carbon Composites.

But it is a cheaper way to produce larger quantities of composite parts, with tooling, typically for non-structural parts though...

Wouldn't be my first choice for cranks...

yeah I'm a bit confused by it too. This looks more like moulding chopped (recycled waste?) carbon fibre blended with a rubbish (polester) resin. Maybe if they tried to align the chopped strands like you do with metal grains when forging I would see why they call it forging but this just looks like moulding with a chopped fibre reinforced plastic. Much the same way you mould with chopped glass in nylon.

I could see it being very tough and good for kids bikes. I can't see it being stiff enough for an adult wanting to put some power through it. Happy to be wrong though.

I though Magura used similar material for all sorts?

Yeah it's more like a chopped fibre/resin "slurry" compressed in a mould, I remember reading about it briefly in one of the engineering comics at work.

I suppose you might get some degree of fibre alignment but it's all chopped, short, homogeneous fibres, so there's also a chance of getting knit lines, or areas with low fibre density perhaps as you can with injection moulded plastics. It's still quite good if you want to produce relatively strong, lightweight, dimensionally accurate parts in higher volume without the labour costs of laying up carbonfibre.

I could be totally wrong and it is the next wonder technology for composite manufacturing...

All carbon forging is not the same

that is basically a high pressure process similar to HEXmc Bulk or sheet

it will give a surfaces a really nice finish on all sides

The interesting stuff happens over at 300 or so tons and basically you can put to bed any thoughts of impact damage or failures.

Paper here:

pretty much as I thought except for the stiffness they are quoting which seems high but then at 1" long fibres that is classes as "long".

No real results in that paper though and kind of hints really that you will have to completely redesign everything to get more stiffness through geometry and allow more material around mounting points due to the lower strength. ie this stuff is very good if you want tough and light but don't care about bulk.

They use a fibre-resin charge material that is cut and stuffed into a heated compression mould s you do get some orientation of the charge during compression which should impart some directionality if you place the charge material in certain ways. But that itself seems time consuming and vulnerable to error which again comes back to a lower level of critical performance and a material you would treat more like wood.

I would much rather see this being used with natural fibres and resins but the work might spin off to those and benefit those. Just like how we are making composite cars at the moment in the hope that it will pave the way to fibre reinforced thermoplastics instead of thermosets. I still think that cars should be steel and aluminium for easy recycling and no thermosets should be used at all.

So it does lend itself well to making cranks?

What's up with indiegogo njee

It's far less regulated that other crowdfunding platforms - your money gets taken even if they don't reach the target, there are no requirements to have any sort of prototype or proof of concept. You could start an Indiegogo campaign tomorrow for a unicorn farm if you wanted. It's usually far riskier and for more dodgy ideas than (say) Kickstarter.