Yeti c-26 replica help

[oliverracing]

bit of background before you all tell me to attempt something else , I'm an automotive engineering student with a bit of a crazy liking to building bikes, to start with bolting components to frames was enough, then wheelbuilding took my fancy until this summer I built a carbon frame from almost scratch clicky, but I've always admired the old Yeti C-26, and especially Tomacs drop bar one!

Image credit to whoever owns it

So my idea was to attempt to use the same or similar methods (with more modern epoxies/bonding methods), as was used on the c26 to mod an old scot summit I have with a dented top tube into a modernist drop bar monstercross tribute to the mighty c-26 -

Image credit to me on bikecad.ca

But I have a few questions, which if there are any experts (or ex yeti guys :roll: ) out that would be willing to help I would be eternally gratefull...
(1)-on the originals where were they most likely to fail?
(2)-how did yeti bond the tubes? (resin type? rough gap between tubes and lugs? any extra reinforcement used?)
(3)-of the originals does anyone know of any that are still ridden hard and surviving?
(4)-dimensions of the seatpost - any chance of a fag packet sketch on how that section worked? (odd question but I'm working out how I'm going to do mine based on an old frame with a 26.6 seatpost)

If any of these things I'm asking are still yetis intellectual property I can be discreet if you don't want to post of the forum feel free to PM me :roll:

I'm planning on building this up with a gear hub for simplicity but short term/for testing it will be run with a 1x8

 

[rumpfy]

(3)-of the originals does anyone know of any that are still ridden hard and surviving?

I know of one that is both original and still actually being ridden as a mountain bike. Every other C-26 is either a reproduction, broken, a wall art show queen, or maybe sees a light parade lap at the local bike festival. I hope I'm wrong, but I've not seen anything to the contrary.

 

[CTK]

Didn't a Grisley or Peugeot have the same carbon tubes?

 

[ridevintagemtb]

1. The ones that failed did so at the bonds. The tolerances provided to Yeti from Easton were off, so the lug/sleeve bond was extremely tight. So much that most of the adhesive (3M Permabond 210 iirc) squeezed out upon application. The ones that did survive failed because of the different expansion and contraction rates of aluminum and steel. Yes, the "carbon" tubes from a C-26 were just alloy sleeves wrapped in a carbon weave.

2. Answered above

3. I know plenty survivors but only a few are being ridden. Member Rumpfy has made a thread on his.

4. All but one had diameters of 27.2. Mine is 27.2. There's one where the owner swears its 26.8. The rear triangle assembly photo is below.

RE: your drop bar intentions. Tomac made them work but later regretted it. Flared dirt drops are really the only way to properly execute a drop bar MTB. Only people who say otherwise are stubborn, content with being uncomfortable, and not getting anything aggressive out of setup.




Ahh... Tomac's DH bike. I'm standing just off to the side of the bike in that photo. Threw a leg over, sniffed the saddle, all that good stuff. For many, the holy grail.

 

[oliverracing]

Rumpfy - nice one - lovely to see one still being used for what they should be, I'm in the crowd of if you stop using it as a mountain bike, it stops being a mountain bike and becomes art (which may not necessarily be a bad thing mind you)
also lovely to see those close ups of the joins - it really does amaze me how little overlap is needed/used on these!

CTK - not sure, but I know raliegh did something similar around the same time. I was planning on manufacturing my own tubes any for this to help get the correct sizes as it seems to be quite hard to buy tubes in the right sizes (and cheap enough to manage on a student budget )

ridevintagemtb -thanks - that seems to tie up with what I had been told previously, I was planning on slightly larger gap (within reason) and slightly more flexible epoxy (am I right in thinking 210 is 100% rigid?), I was also planing on 100% carbon tubes as that's all I can make in my garage In terms of the bonds I was also planing on having a overlap of about 12-15mm more than the originals did just to be safe

EDIT: - as for the drops - already have the donor bike built up with the flared drops and love them (salsa woodchippers)

 

[rumpfy]

Yeti. Not a bicycle of perfect. Mine has held, but some of the bonding isn't as flush as it should be. Its never been a problem in all its years of use. If it ain't broke, don't try and fix it.

 

[ridevintagemtb]

It's the build that really makes that bike

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[rumpfy]

It's the build that really makes that bike

LOL! Fcuk running Bullseye cranks, those things suck!