Karl's V20 variable seat angle solution

[Robertas]

Great to see that you are doing this!

I asked the manufacturer of the hinge about this, and he recommended gluing it only, so I did that, but found that the screw holes were very helpful in fixing the position, so I left the screws in also for extra safety. One or the other on its own is probably strong enough also.

Your picture looks like you have two separate hinges side-by-side. Is that true? In that case I would definitely glue them to avoid that the smaller one rotates against the lower base of the seat and increase bonding strength.

Thanks for the answer. Yes, it`s two separate pieces as seller did not have one 15cm piece, just 10 and 5cm.

 

[Karl42]

Thanks for the answer. Yes, it`s two separate pieces as seller did not have one 15cm piece, just 10 and 5cm.

As I said, I would glue this to the seat on both sides to increase strength. Any MMA glue is probably ok for this, as recommended by the carbonhinge company.

 

[Karl42]

Also, I found it helpful to practice on something small with the MMA glue to get a feeling for mixing and applying it correctly, before applying it to the expensive carbon hinges. Gluing those was certainly a bit scary for me, but then it worked out well and was easier than expected.

Therefore, when you order 2-component MMA glue, get plenty of spare mixing tips so that you have enough to practice, as they are single-use only.

 

[Robertas]

Today I bent the alu back plate into the right shape

Hello Karl, what dimensions of back alu plate you finally used?

 

[Karl42]

Hello Karl, what dimensions of back alu plate you finally used?

The final size I used is 12 cm by 15 cm, the thickness is 2 mm. This is what it looks like at the end of the season:





I put a thin plastic sheet on the carbon fibre as isolation, and then used double sided sticky carpet tape on both sides of the sheet, and used nylon screws to avoid a conductive contact between the alu and the carbon to prevent galvanic corrosion.
The carpet tape would have been strong enough to hold the backplate on its own, so the screws are just for extra safety.

Bending the 7075 alu plate into the right shape was tricky. In the end I used strong screw clamps to clamp one end of the plate to a solid table, and then clamped the other side sandwitched into two pieces of hard wood, and with that was able to overbend it enough until it would take the shape.

On the pictures you can see that the top end of the plate is filed into a sloped edge. This is so that the hasp can slide over the edge of the plate and doesn't get stuck there.

The piece of foam at the bottom of the seat was added to add a bit of support to the hinge, and to prevent the seat sliding laterally in the reclined position. This was just a piece of fairly thick packaging material that I had lying around.

The two small wooden blocks on the side of the frame are used as spacers to allow the backplate to rest there in the reclined position. I think newer models of the V20/V20c don't have these fins on the frame anymore to which I attached the blocks on my bike. In that case I would perhaps cut a strip of the 7075 alu in 2 or 3 mm to extend over the sides of the frame and use the same screw hole used for the hasp to fasten it to the frame, so that this can provide the mounting point for the spacers. Or maybe the support doesn't need to extend over the sides of the frames at all. I just attached the wooden blocks there because my frame does have the fins there. Also, these blocks are provisional and I was planning to replace them with plastic ones that are more waterproof, but haven't got around doing that yet, and the current ones are holding up fine so far.