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-   -   Tubing choice for a fatty (me) (http://www.bikeforums.net/framebuilders/680155-tubing-choice-fatty-me.html)

mudboy 09-14-10 08:52 AM

Tubing choice for a fatty (me)
 
I'm about to embark on my second frame, a 650b wheeled "path bomber" - a bike primarily designed for the packed gravel paths in my area, but also at home running to the store and riding around the neighborhood with my kids.

My initial thought is to use 9/6/9 road OS tubing with a lugset (one of Dazzas) built for a sloping top tube design. I built my first frame from Columbus SPX, so similar butting, but standard diameter. However, I'm using Ceeway to source parts for this build, and the only tubeset he has that is 9/6/9 road OS is seamed Dedacciai. For a number of reasons, I'm not wild about seamed tubing -- unless todays seamed bicycle tubing is significantly different from the seamed tubing of 20+ years ago.

However, there are lighter gage (8/5/8) heat treated road OS tubesets that would also work, but I just want to make sure that I won't be building a noodle. Is a good heat-treated 8/5/8 road OS tubeset too light for a 240 pounder? I'm a spinner, not a masher, and my competitive days are far behind me.

Any advice would be appreciated.

Thanks,

Pete

JohnDThompson 09-14-10 10:41 AM

I would stay with the 9/6/9 Dedacciai. And yes, today's seamed tubing is much nicer than that of 20 or more years ago.

mudboy 09-14-10 12:28 PM

Quote:

Originally Posted by JohnDThompson (Post 11462544)
I would stay with the 9/6/9 Dedacciai. And yes, today's seamed tubing is much nicer than that of 20 or more years ago.

My main concern is when it comes to crimping the chainstays. I'm concerned about the tube failing at the seam when it's crimped.

unterhausen 09-14-10 01:21 PM

then get ROR? i don't think you have to worry about that too much, past experiences notwithstanding

JohnDThompson 09-14-10 08:01 PM

Quote:

Originally Posted by mudboy (Post 11463188)
My main concern is when it comes to crimping the chainstays. I'm concerned about the tube failing at the seam when it's crimped.

Modern seamed tubing is drawn over mandrels like seamless tubing, and this obliterates the weld seam quite effectively.

Silverbraze 09-14-10 08:52 PM

1 Attachment(s)
Quote:

Originally Posted by mudboy (Post 11461855)
I'm about to embark on my second frame, a 650b wheeled "path bomber" - a bike primarily designed for the packed gravel paths in my area, but also at home running to the store and riding around the neighborhood with my kids.

My initial thought is to use 9/6/9 road OS tubing with a lugset (one of Dazzas) built for a sloping top tube design. I built my first frame from Columbus SPX, so similar butting, but standard diameter. However, I'm using Ceeway to source parts for this build, and the only tubeset he has that is 9/6/9 road OS is seamed Dedacciai. For a number of reasons, I'm not wild about seamed tubing -- unless todays seamed bicycle tubing is significantly different from the seamed tubing of 20+ years ago.

However, there are lighter gage (8/5/8) heat treated road OS tubesets that would also work, but I just want to make sure that I won't be building a noodle. Is a good heat-treated 8/5/8 road OS tubeset too light for a 240 pounder? I'm a spinner, not a masher, and my competitive days are far behind me.

Any advice would be appreciated.

Thanks,

Pete

How about using XL tubes (called double over size in the USA)
HT 36
DT 34.9
TT 31.7
ST 31.7
Use .8/.5/.8 tubes and you get a very strong and stiffer frame than a OS .9/.6/.9 tubed frame.
The tensile or yield strength has no effect on the rigidity, that is determined only by the material dimensions.
Up the diameter is my call.
Use 30 x 16 CS, .8 but .9 would be better
You may need single bend CS pending your tyre choice
and do not skimp on seat stay diameter, as they have a lot to do with the back end of the bike, maybe 18mm or even 19mm ones are cool on big bikes or the big fellas.
It is your tyres that do the work with shock absorbtion with big fellas.................................................................... you don't want lots of movement in the stays, or this means breakages one day
Forks, plenty of light and heavy steerers in 28.6 (TrueTemper 28.6 steerer is lighter than the standard Columbus 25.4 steerer)
but I would use the Columbus 28.6 steerer and a wide crown (they are available) and 1.1 mm thick fork blades. (True Temper)

cheers Dazza

mudboy 09-15-10 06:52 AM

Thanks Dazza,

I'm using your road OS lugs for the sloping top tube; ceeway carries 'em. I'll be using the Pacenti P-B-P crown.

Double OS sounds interesting, but I'm a fan of threaded heaset and quill stems, so I need a 31.8 head tube/25.4 steerer. I'm planning on using stout stays and blades.

Thanks

Pete

Silverbraze 09-16-10 07:51 PM

Cool
Have fun
Quote:

Originally Posted by mudboy (Post 11467487)
Thanks Dazza,

I'm using your road OS lugs for the sloping top tube; ceeway carries 'em. I'll be using the Pacenti P-B-P crown.

Double OS sounds interesting, but I'm a fan of threaded heaset and quill stems, so I need a 31.8 head tube/25.4 steerer. I'm planning on using stout stays and blades.

Thanks

Pete


mudboy 09-17-10 08:30 AM

Hey, Dazza, the lugs I ordered (the L5 on Ceeway's site, I believe they are the "Singer" lugs) have a raised line on the points. I've seen enough old French bikes to know that those raised lines are supposed to be there, but do you recommend any specific finishing for them, or should I leave them as-is?

Thanks

Pete

unterhausen 09-17-10 11:35 AM

the raised line has the combined benefit of making the casting more robust and can help you avoid overheating the lug tip. You should remove it. You don't want the lug to be too stiff out at the point. Look at a lot of Dazza's bikes, the points on the lugs are almost totally gone.

Silverbraze 09-17-10 02:03 PM

1 Attachment(s)
Quote:

Originally Posted by mudboy (Post 11479715)
Hey, Dazza, the lugs I ordered (the L5 on Ceeway's site, I believe they are the "Singer" lugs) have a raised line on the points. I've seen enough old French bikes to know that those raised lines are supposed to be there, but do you recommend any specific finishing for them, or should I leave them as-is?

Thanks

Pete

The story of the raised line is all about casting production, nothing else.
In 2005 I visited LongShen Taiwan where my lugs and Richard's and 95% of the worlds frame castings are made.
It was during this visit that I discussed the raised ridge on lug points that I had seen before on another brand of lugs. They grabbed the idea, purely for helping the flow of metal during the pour fill the fine tip of the lug, thus reducing the failure rate during the pour. They thought it a great idea and I am all for helping them out, they have got to make living as well.
The ridge on the lugs and some left over gate is left on the seat binder boss on the seat lug because the builder will do a better job of filing them off than a factory worker who grinds 15,000 of them each day.

One needs to be careful filing/cleaning the shoreline at the tip as the raised ridge can over hang the final flow of the shoreline. I remove all before brazing.


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