Guru Carbonio

[Bentley]

Anyone know anything about this bike? Obviously I could have posted this in the PSA thread, but I’m curious about the bike. Lugged carbón with Titanium... interesting. My fear would be catalytic corrosion. Anyway, anyone know about this bike?

Ray

Oops https://ebay.us/mb9MZU

Forgot

[Clean39T]

Anyone know anything about this bike? Obviously I could have posted this in the PSA thread, but I’m curious about the bike. Lugged carbón with Titanium... interesting. My fear would be catalytic corrosion. Anyway, anyone know about this bike?

Ray

Oops https://ebay.us/mb9MZU

ForgotI don't, but that is from forum vendor "Cool Planet Bikes" if I'm not mistaken...

Sent from my Pixel 2 XL using Tapatalk

[kingpin75s]

I have only heard good things about the ride quality on these.

I know some of the all carbon super light Guru's had issues due to pushing the weight boundaries, but this is obviously a different construct. Corrosion can always be an issue but I have had no issues with any metal/carbon frames I have built that have been running for over a decade.

My first dream for me bike was a 2003 Guru Veloci'Ti that I bought NOS in 2006 and ran for a decade.

[dave thompson]

Anyone know anything about this bike? Obviously I could have posted this in the PSA thread, but I’m curious about the bike. Lugged carbón with Titanium... interesting. My fear would be catalytic corrosion. Anyway, anyone know about this bike?

Ray

Oops https://ebay.us/mb9MZU

Forgot

A carbon/Ti joint has the least possibility of corrosion issues. Calfee uses Ti as the bottom bracket shell on their carbon bikes for this very reason.

[Dino Suegiù]

The Guru Carbonio/Ti had an excellent reputation, sturdy. Guru were so good, and the price for that frameset + looks very fair. People are selling Reynolds Ouzo Pro forks alone for $125+ used/mint to ~$250 new.

A carbon/Ti joint has the least possibility of corrosion issues. Calfee uses Ti as the bottom bracket shell on their carbon bikes for this very reason.

Yes, this exactly.
I think Calfee used to isolate any alloy parts from the carbon with fiberglas, before using more reliable titanium components.

Further information from the old but still excellent "Calfee Technical White Paper" (https://calfeedesign.com/technical-white-paper-1/):
4. Interfacing Carbon with Metal Parts
...Material discontinuity (where two dissimilar materials are joined) creates stress risers (concentrated areas of stress). Coupled with galvanic corrosion, thermal expansion, or an inadequate bond, these areas can catastrophically fail...

...Two ways of addressing this issue are to use materials with similar coefficients of thermal expansion to join the tubes without bonding and to use mechanical retention systems along with bonding for parts attachments. If metal must be used it should be titanium. Titanium, unlike steel and aluminum, is not susceptible to corrosion. Although a metal, it also has thermal expansion characteristics fairly similar to carbon fiber while aluminum and steel are quite different...

...The best solution lies in creating a system where, if the attachment of metal parts is required, they should be formed with a material that exhibits similar properties to carbon fiber. An important requirement is that the material used should have a coefficient of thermal expansion similar to carbon. Titanium is the most appropriate metal for use in applications requiring metal mated to carbon since it is highly resistant to corrosion and it has a similar thermal expansion coefficient to carbon’s. Additionally, if bonding is required, it should be combined with a mechanical retention system. Mechanically retained parts reduce or eliminate the reliance on bonding alone...

It seems that the Guru Carbonio/Ti employed all these practices.