Velocite filament wound rims

[bruto]

Thank you, Victor

curious how machining the rim bed affects its mechanical properties - you're cutting right through those crisscrossed filaments, aren't you?
I would conjecture it requires more material to be left there, but the difference between FW and CTL versions of the 507 TCD rim is mere 10g

[vmajor]

I cannot actually disclose how we make the rims, but there are no structural drawbacks.

Regarding the weight difference between 507 rims, the FW version is a projection as we are still working on it.

[kobec]

Thanks Victor, I completely agree with you that the carbon fiber technology hasn't changed much, and it's refreshing to hear and exciting to see that people like yourself are breaking free from the mold!

Coming back to FW vs CTL then...if we had a FW 507 and a CTL 507 - is there any reason to pick one technology over the other? e.g. one is lighter but less stiff, the other is "heavier" but more stiff etc. Would the CTL be more expensive than the FW for the same wheelset?

[vmajor]

CTL will cost more...and despite inherent superiority of CTL compared to the standard segmented rim construction, it will by default be more prone to variation than FW process. Mechanically, not sure yet as we have yet to make the FW version. We are aiming for parity in major mechanical properties (Stiffness, strength) but I expect different riding behaviour simply due to vastly different layup. Our FW rims now exhibit better road holding compared to standard rims for example.

[bruto]

FW looks better, you can tell that much from the photos
if you dig the argyle pattern, that is

[kobec]

Interesting....it sounds to me like FW is still the way to go, plus it was part of your original vision! Any idea when the 507 FWs will be available?

[vmajor]

We are working on the FW pattern now, so hopefully we can start sampling before the end of the year.

However, CTL is still a superior process compared to other hand made rims, so do not let the lack of FW version hold you back

[kobec]

Hahah! I suppose you're right.

Last question (for now) - what are the tire ranges for the 507? (for the 19mm internal). Any issue running a 35mm and taking it off-road into gravel?

[vmajor]

There should be no problems with wide tires or with gravel riding.

[bruto]

I wonder if FSE are licensing your technology, Victor, or have found a way to work around the patent(s)
(see fse.bike)

[vmajor]

No they just copied our basic story, our claims and added quite a lot of their own claims, but the "wound" rim they show looks definitely woven not wound. Woven automatically made rims have existed for a while, originally developed by the Technology University of Munich (TUM) then sold via Munich Composites, and one other whose name escapes me. This is not winding.

So, in short, nobody figured out how we do what we do and FSE revolutionized nothing that I can see.

[Fiery]

It's possible to automate the production of woven carbon rims? How is it done and why is it not done more often?

[vmajor]

It is indeed possible. It uses a sock or hose weaving process at as a basic step - similar to what BMC used to get Impec manufactured and what Time uses in house to make their frames and forks. The hose weaving process was invented in the 1920s to weave reinforced hoses - specifically fireman's hoses.

Carbon fiber is used instead of cotton and you get super strong hoses. Using modern technologies and clever tricks you can then weave this basic sock shape into more complex shapes, now referred to as 3D weaving.

Resin is infused after the fact as weaving tacky fibers is not practical and this is where the cost becomes an issue, beyond the cost of the weaving machine (see Time video on YouTube) is the resin infusion process, called RTM. RTM process is again dependent on a very expensive machine. Thus once you amortize for all the rather large equipment costs and forecast unit sales, each unit sold becomes expensive.

Thus there are two disadvantages to automatic weaving production of parts for bikes:

1. High unit cost due to high cost of the manufacturing process
2. Woven parts will never be as stiff or as strong as wound or even (carefully) UD laid up parts due to fiber crimp problem with all woven fabrics.

V.

[bruto]

theirs actually look like the common 3K sheet
so weaving allows them to 1) automate 2) boast about continuous fibers but 3) have way less tension than with FW process and therefore, crimping ?
I wonder if using more fiber (thicker weave) would alleviate the lack of stiffness at all (they use less, though, if the published weights are correct)

[vmajor]

Crimping is a result of the weaving process, not tension. This image from Oxeon explains it quite well: http://www.hydroflex-surfboards.com/fil ... xtreme.jpg

Crimping is not good if mechanical properties are the first priority. Crimping is good if you want good drapeability of the fabric and better surface finish as crimped fabric can stretch a little and thus conform to the mold a little better.

The great equalizer of all fiber reinforcement weight calculations is gsm = grams per square meter and basically the higher the gsm the better the mechanical properties, but higher the weight. Thus for crimped fabric you need more gsm to achieve the same stiffness and weight that is achieved if you use non-crimped fibers.