View Full Version : Seat Mast Top for ISP
Lundbeck
07-12-2011, 05:09 PM
I just finished up a frame and for the life of me I can't find a seat mast topper. I'm looking for something that will work with rounds tubes. This specific seat tube is 28.6. Anyone know of something or someone that can make it for me?
1centaur
07-12-2011, 05:44 PM
Try e-mailing this guy:
cgaulzetti@internationalbike.com
I suspect he looked across the seat topper universe in connection with his own frame line, and ended up having some made, if I recall.
Just looking at Google, 28.6 seems tough from the obvious sources.
Idris Icabod
07-12-2011, 05:44 PM
Ritchey makes one in various sizes and setbacks:
http://www.ritcheylogic.com/dyn_prodfamily.php?k=299426
I just had a closer look and it is too big, perhaps you could use a shim?
EricEstlund
07-12-2011, 11:41 PM
By just finished, did you mean just finished making the frame?
To the best of my knowledge there are no current production 28.6 toppers. 28.6 seat tubes are pretty much only available on steel frames these days, and commercially available round toppers are designed for production carbon and aluminum frames with masts and typically in 30.25, 34.9 and 38.35 (with other odd sizes here and there).
For 28.6 you are likely going to have to fab your own external topper or use an internal seat post. I don't want to be presumptuousness- but don't cut an internal stubby super short unless the mast was designed to deal with that sort of stress.
Lundbeck
07-13-2011, 10:05 AM
Thanks for the advise guys.
@Eric, yes I built the frame and it is steel. I don't have the proper tools to fab my own topper unfortunately. Please be presumptuous, I always appreciate advise.
Cheers,
Grant McLean
07-13-2011, 10:15 AM
There could be some internal type toppers that would fit a 27.2
inside diameter, like the Columbus Ghost. Or you could just cut
down a thomson post, and use a seat collar at the top.
Do you need setback post, or a zero?
Not 100% sure what size this one is.
http://www.columbustubi.com/eng/4_2_26.htm
-g
jimcav
07-13-2011, 10:48 AM
Thanks for the advise guys.
@Eric, yes I built the frame and it is steel. I don't have the proper tools to fab my own topper unfortunately. Please be presumptuous, I always appreciate advise.
Cheers,
I got the bike and topper for my nephew. he mismeasured things and the original allow ritchey ISP topper was fine. so i have this high end carbon MCFK one (which allows more height adjustment--something he thought he needed, but did not). anyway, it is of course 30.2 diameter, but i think something non-compressible as a shim would be fine--something like the 1' to 1 1/8' stem adaptors; so if you can think of a good sleeve/shim material you could look into one designed for the addict.
EricEstlund
07-13-2011, 03:45 PM
Pretty sure all the internal expanders (current) are either for BMX sizes (25.4) or 31.6 for internal in carbon. Please correct that if I am wrong- I'd like to be aware of more options.
This isn't speaking to your frame, but my biggest concerns when seeing some ISP's made in steel is that the post portion itself as well as the "seat tube" part in the seat stay/ top tube cluster are under built. There is more to doing it (well) then just making the seat tube taller.
If it is built with an .8/.6 standard 28.6 tube (or thinner) then I would probably run a light seat post that ran below the level of the top tube and call it a day (or trim it down for a standard collar).
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