Strut brace size

A1ex · Post by **A1ex** » Tue Jul 03, 2012 12:19 pm

Just about to order some of this stuff to make the CF strut brace;

http://www.easycomposites.co.uk/Categor ... -Tube.aspx

It's 3 times the strengh of aluminium & 1.5 times stronger than steel

Do any of you know the diameter of the main bar on your strut brace so I can make sure the strength/stiffness is comparable?

Post by **NafemanNathan** » Tue Jul 03, 2012 12:40 pm

Totally depends on what make of brace people have. I'd say my Neuspeed one is about 20mm diameter. Most are ovalised though and probably about 40-45mm x 20mm.

A1ex · Post by **A1ex** » Tue Jul 03, 2012 12:46 pm

I'll go with 20mm, I was looking at the 10mm stuff but by the sounds that'll be too small.

Next question then

how long is the brace, just the tube? the 20.8mm carbon tube is £30/m and is done to the nearest half

fingers crossed for 0.95m

Post by **Merlin** » Tue Jul 03, 2012 12:47 pm

What do you plan to do about the feet? On most braces its the feet that is the weak point.

Post by **Donald** » Tue Jul 03, 2012 1:00 pm

As Nafe said the Neuspeed one is round but my Spoon one is like a rounded rectangle.
As for length, wont different braces have different bar lengths due to the feet design, shape of the bar, etc.
Again using the same examples, the Neuspeed brace is a straight thingy across the bay, whereas the Spoon one bumps up.

IIRC the front braces are different between 5G and 4G, with the 5G overall difference being about 10mm or something close to that? The rear braces are interchangeable.

A1ex · Post by **A1ex** » Tue Jul 03, 2012 1:05 pm

I found my dissertation on the weekend, it's got optimum designs (done by myself) for multi layer fibre layups. Will be doing a 6 layer symetrical setup (very stiff) which will be vacuum formed and bonded to the cross member. One of my designs was 5 tmies stronger than titanium

. Connection will be similar to how it's done on the type s brace but obviously with CF & resin rather than welding steel.

The basic design is being taken from the shape of the ebay strut foot but I will be modifying it with extra stiffeners to carry some extra load and reduce flexure. The design will also make sure the cross member doesn't pop out of either end or fall out. I'm thinking V2 will be adjustable too so it can be pre-loaded.

Post by **Donald** » Tue Jul 03, 2012 1:09 pm

I'm interested in this if it works out well

I think ideally you need to have a look in your own bay and work out what shape/dimensions will work best, like looking at the best point to have the foot begin, etc. And if you're basing it on the Type S one make sure it works without the need for Type S top hats

A1ex · Post by **A1ex** » Tue Jul 03, 2012 1:17 pm

already made the type s top hat mistake

It will be very loosly based on the ebay one as it uses a straight bar and the feet will fit my 3 stud top hats. Making it from fibre I can modify out all of the stupidities that are in it at the moment.

Post by **NafemanNathan** » Tue Jul 03, 2012 1:27 pm

What Gordon said. You need the feet first and then measure between them. I had assumed you were going to use some existing steel feet. Structural carbon fibre parts still make me nervous

bb1boy · Post by **bb1boy** » Tue Jul 03, 2012 1:33 pm

I once had carbon fibre handlebars on my mountain bike, they were called Barflex because they were designed to flex slightly to absorb some shock - but I never trusted those things, they were scary as hell ..bombing down a track with bloody bendy handlebars is not cool at all. That said, they never broke...