Carbon fiber rear rack?

[cwah]

Hello all,

I'd like to start playing with carbon fiber, my idea is that if that can be strong enough to support a bike, it may be good enough for a 10-15kg rear rack on a bike?

Can I start with a kit like this one?
http://www.ebay.co.uk/itm/Carbon-Fibre-Fiber-Laminating-Starter-Kit-Epoxy-Resin-Cloth-Weave-Mat-PVA-/261322661493?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cd80b5e75

It looks like it's just enough for a small job, if I need more, is there place to buy it for cheap?

Thanks lots

 

[arkmundi]

Carbon Mods seems to offer any quantity you want. Their starter kit is just that, to give it a try. Thanks for the referral.

 

[silviasol]

Check out compositescentral.com. To make a pretty looking part with the square patterns you see on high priced premade stuff you need a vacuum infusion set up and a mold making materials, making the mold takes just as much time to make as the carbon fiber part. I believe that is £39.95 is around $80usd which is more then 5 maybe even 10 times mark up for what that stuff is worth. Just buy some carbon fiber and search for resin. You can get a big roll of carbon fiber for around $50usd and probably 3-4 times more resin/hardener for $40-50. I use composites to repair stuff I sell but never got around to getting into carbon fiber but have been researching it for years.

 

[d8veh]

The reason to use carbon fibre would be because it is very strong compared with its weight. You can get the same strength with other materials as long as you construct it right.

That carbon fibre kit is unsuitable unless you already have expertise in making carbon fibre tubes. If you definitely want to go with carbon fibre, you should start with ready made cf tubes, then add some mounting points. Before you start, you should investigate the Youtube videos that show how to make frames out of cf. It's not easy.

 

[ScooterMan101]

There is at least one place , here in America, that sell already made carbon fiber tubes, I forgot the name of it right now, a search will find it and others,
So across the Pond , where you are there must be places as well . What about the Soviet Union ? or is it risky to order anything from there ?

 

[amberwolf]

Regardless of material used to make your rack, keep in mind that the rack doesn't have to just carry a certain weight.

It has to handle sudden increases in weight up to several times the actual weight of the carried items due to inertia from bumps and potholes.

It also has to handle the weight not only straight down, but in side-to-side sway and side-loading, depending on how you pack it on there and how you ride and park, and what situations you encounter on a ride.

All the mounting points for the rack also have to handle the side-loading and bending, repeated constantly from vibration/etc., as well as the vertical loads of the carried items and shock forces.

Look up "rack" in my posts on ES for a number of design thoughts on them over the years, in reference to various existing rack designs and modifications people have done or wanted to do to their bikes.

 

[xenodius]

if you have a knack for CAD, and access to a 3d printer, mold-making is an excellent application for them. Especially since you can make high-infill molds which are fairly stiff, but very light, and can be used as a permanent core. There's a CAD plugin compatible with Autodesk, Solidworks, et al. called 3dPrintTech that lets you cut up really large prints into, essentially, custom Legos. Use ABS and brush with acetone before assembly or spray a blast of carb-cleaner on it and it'll be as if it were always one piece.

You can even brush or spray your ABS mold and lay up your first layer of cloth into the softened shell before you actually impregnate and bag it.

 

[scfoster]

go for it.. Carbon fiber can be addictive.

Here's one of my "summer projects' from back in the late 80's. Building a whole fuselage out of composite technology was cutting edge back then.

Learned a LOT about how to build large structures with carbon fiber technologies. As posted earlier, "how" to make things can be a whole lot more work than the actual manufacturing process.

One thing to note is failures tend to be catastrophic, rather than metal which bends and can give a lot more warning. Distributing loads at attach points will be the most difficult part and you need to keep crushing in mind when bolting things together.

 

[Chalo]

You can probably learn the same lessons much more cheaply and just as effectively by making a rack out of bamboo sticks and fiberglass tape with two-part resin. Or bamboo sticks plus hemp twine and wood glue, for that matter.

Just like CFRP, bamboo isn't good at supporting point loads-- like the loads that luggage hooks and inadvertent impacts apply frequently to bicycle luggage racks. If you use "throw over"-style conjoined panniers, carry only soft items, and never let your bike fall over or get bashed into by other people parking their bikes, then either bamboo or CFRP should do the job fine. You'll need to provide metal inserts at the points where the rack bolts to the bike, though.

 

[tomjasz]

My brother runs a carbon fibre fabrication plant and made hollow rods for a time. I have a bunch I used as plant supports and was shocked at how fast they failed from uv exposure and that's in Minnesnowta, not exactly the sunshine capital. Faster than the fibreglass. Never asked about uv treatment but it's on my curious list. Obviously painting would change or fix that but interesting to note.

 

[silviasol]

If you want a quick but strong build buy tubing/flat premade pieces and some carbon fiber tow. Just wraping the carbon fiber tow to connect the tubes then adding superglue to the carbon fiber tow will make a very strong hold, then you can file down the tow to make it look nice.

Also carbon fiber is a bit overkill for a bike rack. You can get other materials that will work well, just some pvc tubing if made correctly will make a very strong build. Then use carbon fiber tow for the connections.

 

[tomjasz]

Carbon fibre shafts, seconds, are pretty cheap...

 

[Chalo]

Carbon fibre shafts, seconds, are pretty cheap...

Golf clubs? Arrows? Fishing rods? We need more clues as to what you're discussing.