Custom Titanium Options

[Mikej]

Originally Posted by tv_vt

Don't know. Could also tie into their build philosophy.

I know Eriksen only does 27.2 ID seat tubes, or almost 'only'. Certainly doesn't hurt the ride at all.

Ti is for sure harder to work with than steel.

Depends on the size- there are 30.9 Eriksen bikes out there. Friend had one nd it was sooo bumpy for my 155 lbs body.

[tigoat]

Originally Posted by old fat man

Please show me the ti insert that Paragon sells to bring a 34.9 tube down to 27.2.
It's okay to not know everything

Call them, they will make you one, as they make a lot of custom machined parts not shown in the catalog. These seat tube inserts are just a simple stepped sleeve. Heck I could machine you one with a manual lathe (no CNC) with you pay me enough.

[tigoat]

Originally Posted by Kontact

It isn't the same, but it is brand differentiation. Seven, for instance, refuses to do quite a range of things because they believe it adversely affects the ride and long term durability of the frame. Other companies have their own philosophies that limit what they will or won't do.

We should like that these companies have created their own sets of rules through long experience, rather than getting peeved that every custom maker is like every other.


Does anyone actually complain that Colnago won't supply them with a curved fork or that Spectrum won't TIG a steel frame? Let's get real, here.

I think we are on the same page here.

[Jeff N.]

[QUOTE=old fat man;2366256]Did you even read the response that Mike provided to you?[/QUOTE .... ...

[Kontact]

Originally Posted by tigoat

Call them, they will make you one, as they make a lot of custom machined parts not shown in the catalog. These seat tube inserts are just a simple stepped sleeve. Heck I could machine you one with a manual lathe (no CNC) with you pay me enough.

And what a huge chunk of pointlessly heavy machining it would be.

[tigoat]

Originally Posted by Kontact

And what a huge chunk of pointlessly heavy machining it would be.

Indeed. That is what you get when you have to step it down that much. In fact, another way of doing it would be to press (permanent not those slip in ones) in an aluminum sleeve instead of making the sleeve entirely out of titanium.

[Kontact]

Originally Posted by tigoat

Indeed. That is what you get when you have to step it down that much. In fact, another way of doing it would be to press (permanent not those slip in ones) in an aluminum sleeve instead of making the sleeve entirely out of titanium.

Well, you can always accomplish that with a shim, but most Ti builders have gotten away from aluminum sleeves - probably because of the corrosion issue. But it would certainly be easy to use a thick CF sleeve.

I just don't understand the design rationale behind having wildly different post and tube diameters. No one would put a step in a seat mast style frame.

[Butch]

I can give a little insight as to how and why Moots uses 27.2 and 30.9 and what drove that decision. Obviously 27.2 is a great diameter for a seatpost and a Ti seatpost especially. The way Moots makes that size is to use an aluminum glued in insert to bring the 30.9 ID of the insert down to 27.2. We chose 30.9 because it is a popular size (dropper posts readily available) and so the insert welded into the top of the seat tube had a good diameter to wall ratio. As the ID grows for a given OD the wall thickness gets thinner and with titanium the distortion that takes place when the top tube and the seat stays are welded making it out of round increases dramatically. This makes it difficult to have a round interface between the post and the insert.
The other reason Moots selected these sizes is to provide an in house made seatpost. The materials Moots purchases from Sandvik for the seatpost material has the diameter held to a very tight tolerance +0.000" -0.004" in OD and needs to be ordered 1000' at a time. Again the diameter to wall ratio plays a part in getting a post that is strong and lightweight and the mill needs to inspect each tube to make sure it is to the diameter spec.
One more thing I want to share here that might be a little off topic is that the maximum diameter to wall ration before the "beer can" effect hits is 46 to 1. Working with Ancotech, Sandvik and Haynes over the years with developing tubing for the Moots bikes I learned that when the diameter goes up getting a heat treated tube in a CWSR state becomes very difficult to keep the tube round and straight. This is why whenever you see a titanium tube that is 44mm or bigger it is made in China and will be annealed. RMI used to make a 1.75 diameter tube that was seamed in 3/2.5 and Haynes used to make a 1.64" diameter tube in 0.035" that was CWSR as well. When we bought that material the engineer at Haynes called and was quite proud of pulling off that dimension with the mechanical properties they achieved.

[Jeff N.]

I must respectfully disagree about 30.9 being a popular size with seat posts. Unless you a dropper type seat post that you mention, or want an ugly, no-setback Thomson or some other Chi-wan-made post, your options are quite limited, IMO (Enve? Zipp? Deda? Fizik? Forget it). I own several Ti bikes (Holland, Mosaic, Lynskey, Passoni) that're spec'd with 31.6 posts (and it is the size that I'll request for any custom Ti frame if it's available), because of the added stiffness they provide. I'm a big guy. These frames have quite a bit of TT slope, resulting in a lot of seat post showing, so the added stiffness that the 31.6 post provides (over a 27.2) is a real plus.

[sandyrs]

Originally Posted by Jeff N.

I must respectfully disagree about 30.9 being a popular size with seat posts. Unless you a dropper type seat post that you mention, or want an ugly, no-setback Thomson or some other Chi-wan-made post, your options are quite limited, IMO (Enve? Zipp? Deda? Forget it). I own several Ti bikes (Holland, Mosaic, Lynskey, Passoni) that're spec'd with 31.6 posts (and it is the size that I'll request for any custom Ti frame if it's available), because of the added stiffness they provide. I'm a big guy. These frames have quite a bit of TT slope, resulting in a lot of seat post showing, so the added stiffness that the 31.6 post provides (over a 27.2) is a real plus.

Enve absolutely makes a 30.9 post as do lots of other brands.

Oh and the thomson setback post comes in 30.9 too. Seems like you’re confusing 30.9 (common) with 30.6 (found on a few high end steel tube sets, far less common)

[Jeff N.]

Originally Posted by sandyrs

Enve absolutely makes a 30.9 post as do lots of other brands.

Oh and the thomson setback post comes in 30.9 too. Seems like you’re confusing 30.9 (common) with 30.6 (found on a few high end steel tube sets, far less common)

No confusion. I stand corrected on the Enve. Give me "lots of other brands".

[sandyrs]

Originally Posted by Jeff N.

No confusion. I stand corrected on the Enve. Give me "lots of other brands".

Thomson, Ritchey, PRO, 3T, Easton, whisky, salsa, I’d keep going but that’s what the 30.9 filter on any major online bike shop is for. http://www.jensonusa.com/Rigid-Posts?Diameter=30.9mm

[Jeff N.]

Originally Posted by sandyrs

Thomson, Ritchey, PRO, 3T, Easton, whisky, salsa, I’d keep going but that’s what the 30.9 filter on any major online bike shop is for. http://www.jensonusa.com/Rigid-Posts?Diameter=30.9mm

Thanks! I'll take a look! Looked. All ugly, all look to be for MB's. I give.

[Kontact]

Originally Posted by Jeff N.

I must respectfully disagree about 30.9 being a popular size with seat posts. Unless you a dropper type seat post that you mention, or want an ugly, no-setback Thomson or some other Chi-wan-made post, your options are quite limited, IMO (Enve? Zipp? Deda? Fizik? Forget it). I own several Ti bikes (Holland, Mosaic, Lynskey, Passoni) that're spec'd with 31.6 posts (and it is the size that I'll request for any custom Ti frame if it's available), because of the added stiffness they provide. I'm a big guy. These frames have quite a bit of TT slope, resulting in a lot of seat post showing, so the added stiffness that the 31.6 post provides (over a 27.2) is a real plus.

A quick look on Ebay shows Enve, Easton, Raceface, Shimano, Fizik, Specialized, Ritchey, KCNC, and Kore readily available in 30.9. Is there some particular feature you're looking for in a 30.9 post?

[cadence90]

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