With all due respect, you have it wrong on what I do in "'tube-to-tube" construction.
My tubes are made for me per order, in the US, material(pre-preg), laminate is unique in each tube. My investment in stay molds is also unique to my brand, my design and was also expensive. My joints are wrapped with very high quality UD prepreg sourced in the US with the same resin system as the tubes. My joints are meticulously laid by me and only me. OOAC Vacuum bag cure with assisted pressure distribution in a process outlined in 3 US patents pending(unpublished). The results speak for themselves.
I am sure you have seen many "tube-to-tube" processes and see low quality and low technical processes but I assure you not all are created equal just as in your world of bladder molded monocoques.
You can take a queue from the picture here. Right out of the oven. No sanding needed, only the texture of the "peel ply". Only need to file off the flash just as in your molding. This joint was layed in one shot with no secondary cosmetic layer after sanding(like so many). This is a well consolidated void free laminate co-molded to the tube junction. In all of my destructive testing I have never been able to create and instance of cohesive or adhesive failure between the substrate and wrap. Load to failure always is drawn far from the joint and generally takes dynamic loads of well over 1200lbs to failure in a front impact on my typical 900g frame. If you know bike engineering, you know this is a very excellent.
My question for you is "weave" throughout the laminate?? This is not so good IMO. And given the weight of your frames, I worry about interlaminar sheer between layers of woven fabric as well as the overall lower tensile strength of crimped woven broad goods in the laminates I see in the posts. Can you address this? They do not look like spread tows. Why no UD in there?
Mattias Hellöre wrote:
There´s some main differences here.woven
Monocoque OR tube to tube (commonly called tube to lug).
Tube to tube construction is easily done with small investment.
1. Buy or make tubes.
2. Buy or make lugs.
3. Glue them together
4. If neccessary add carbon weave on joints and critical areas.
5. Sand it, paint it.
6. Sell it.
BIG investment for molds often in 2 or more parts, separate molds for each size, some manufacturers take shortcuts here and making moulds for headtube and then seat and toptube and lower half of seat tube and downtube maybe chainstays.
1. Make moulds.
2. Buy carbonfiber (prepregged to your spec).
3. Read layup howto for each customers needs.
4. Do it in one pass.
5. Put in oven and then make minor finish adjustements for parts, glue them together.
6. Sell it.
Monocoque is in my eyes a perfect solution IF and only IF it was done for a big part of frame not making shortcuts and do universal fitting.
I walked around in Eurobike and could see raw and cutted up frames in flesh, not impressed of the finish when comparing to the price tag.
In this case Rolo has succeeded, why?
I assume they use a front triangle mould, a chainstay mould and last a seatstay mould.
Three big parts, easily replacable if you crash or damage the frame, BUT in same time you can get a finetuned frame due to different layup, as there´s possibility with different layup, adding and subracting carbon fiber for a desired performance.
With that said, in a tube to tube frame you are not free to make such options, as the tubes are PREmade, or bought in bigger volumes to your spec or standard, not economically good to have a lot of detailed tube spec in stock, only a very few can do it.
You all know whose they are and they are so good, no namedropping here.
If a specialist frame maker would do the tubes from prepreg weave rolls ground up to a finished frame, what would it cost?
Seriously?, in my eyes very time consuming work with too small profit in this business.
For me as amateur carbon butcher it would be a lot of workhours invested then I need to have a competitive pricing quotes too.
Main flaws with lugged frames or separate part monocoque frames is:
Lugs arent flexible as fillet brazed steel joints.
Too big difference in degrees for example 50 cm frame to 56 cm frame gives visible holes in lugs.
1. Separate lugs for each frame size or 2 sizes = expensive.
2. Moving over to no lug construction = time consuming.
Monocoque universal frame parts:
Main flaw with them like GURU and many other that boasting about full monocoque frame construction yada yada.
1. Separate moulds for lower parts of seat tube and BB and headtube.
2. Separate mould for headtube and front toptube, of course upper part of downtube.
3. Upper seat tube and rear toptube.
4. Chainstay and seatstay mould.
Pro: swap out a mould to a smaller or bigger: another size.
Faster production, all layup is same for this specific mould.
One big investment, better payoff.
Con: stack and reach not consistent and flexibility/stiffness ratio is not consistent for each frame size, small is rock solid, bigger is flexy.
BIG glue joints give a unpredictable manner for this tube, what´s the point with expensive good carbon fiber when you splash on 30% of this surface area with glue that have stiffness numbers 1/10 or worser of your $$$ prepreg roll of carbonfiber when you are gluing together the frame for a random customer.
Hope I made it readable from my view of things.
I have no university exam so don´t take my words as truth.
My view is based by EXPERIENCE with making these things for living.