Seatpost size: 27.0 or 27.2 mm
12-01-22, 01:40 AM
#26
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Cool Lookin' Bike, Dude! it's a step up from the Bianchi MTB's of that age i've seen... Well worth Restoring.... REMEMBER.. As you clean up the Frame tube, the DEBRIS will fall Into The Bottom Bracket area... my advice is to Remove the Crank and Bottom Bracket! If you can't do this, then Lay the Bike On It's SIDE as you clean the rust out of the seat tube, then Empty the Seat tube frequently... and Do Not sand too much out,or your new seat post will slide right down in and be a pain to set correctly.. you can make a flapper sanding tool with a piece of 1/4" or 5/16" steel rod and a Hack saw with a fine tooth blade, 24 tpi or 32 tpi... and some 2" 120 grit Emery cloth strip from a hardware store. you'll need a hand drill too, but WAY easier. Just remove the outty rust, no need to polish every pit out of the inner surface... test frequently, dump debris frequently.
Last edited by maddog34; 12-01-22 at 01:51 AM.
12-01-22, 01:46 AM
#27
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BioPace, U brakes, "X" frame design... a classic example of the early 1990s attempts to better the MtB experience. At least Bianchi saw the reason to not install the rear U brake on the chainstay
Interesting that the catalog shows an Al post and the OP's bike has a steel one... Andy
Interesting that the catalog shows an Al post and the OP's bike has a steel one... Andy
and good point about those mud catcher Brakes...;-)
Last edited by maddog34; 12-01-22 at 02:02 AM.
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12-01-22, 08:10 AM
#28
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12-01-22, 09:34 AM
#29
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More proof that a picture is worth a thousand words. Both the problem and solution are now obvious.
The problem is the rust, and the post will fit perfectly with a light sanding to remove it. Or replace it with an aluminum 27.2 post.
BTW - be careful and do not overnighter the clamp. The ears seem to be bent inward, probably from overtightening in the past. Keep it up and you might Crack the tube, or bend them in enough to touch.
The problem is the rust, and the post will fit perfectly with a light sanding to remove it. Or replace it with an aluminum 27.2 post.
BTW - be careful and do not overnighter the clamp. The ears seem to be bent inward, probably from overtightening in the past. Keep it up and you might Crack the tube, or bend them in enough to touch.
I no longer overtighten.
12-01-22, 09:49 AM
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John, like me, looks to be a sort of historian of design. I had the great opportunity to work for a shop that collected turn of the century (the1899/1900 turn, they considered WW1 as their cut off for collecting) bikes. Each winter we would service one or two of the collection and I got to have hands on experience with bikes that were 75ish years old. This just as the Asian invasion began and through the 1984 Olympic build up. The claims many made as they brought out new products were interesting as I had that 75 year old example of the "NEW and BETTER" product, but done in wood and hide instead of metal, plastic and vinyl. I thought it was pretty common knowledge that Shimano had a department that only did patent searching for both the base designs and their expiration dates, than "borrow" the expired designs.
An interesting part of Bianchi's claim is the separation of the pedaling stiffness need and the bump compliance and how a frame handles them. It seems to my lay eyes that going from a main frame that is a 4 sided structure (common "diamond" frame) to a design that has only triangles as the structural shapes would result in greater stiffness. Not exactly the changes that I would think adds compliance or absorbs road shock. But I'm sure that this claim was written by the marketing dept (or by extension, the magazine writer) and not by an engineer.
I do agree with the comments about the poorly done seat post binder. I've seen many of this type of welded on ears become bent inwards on many bikes. That, as a MtB, the binder could/would be loosened/tightened often this poor binder design is particularly sad. I suspect this bike is one of the Asian made Bianchis and that Bianchi didn't have a lot of design detail involvement beyond the "X" main frame aspect. But this is one more example why Bianchi is a bit player in the North American market, both back then and now. Andy
An interesting part of Bianchi's claim is the separation of the pedaling stiffness need and the bump compliance and how a frame handles them. It seems to my lay eyes that going from a main frame that is a 4 sided structure (common "diamond" frame) to a design that has only triangles as the structural shapes would result in greater stiffness. Not exactly the changes that I would think adds compliance or absorbs road shock. But I'm sure that this claim was written by the marketing dept (or by extension, the magazine writer) and not by an engineer.
I do agree with the comments about the poorly done seat post binder. I've seen many of this type of welded on ears become bent inwards on many bikes. That, as a MtB, the binder could/would be loosened/tightened often this poor binder design is particularly sad. I suspect this bike is one of the Asian made Bianchis and that Bianchi didn't have a lot of design detail involvement beyond the "X" main frame aspect. But this is one more example why Bianchi is a bit player in the North American market, both back then and now. Andy
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12-01-22, 11:31 AM
#31
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Cool Lookin' Bike, Dude! it's a step up from the Bianchi MTB's of that age i've seen... Well worth Restoring.... REMEMBER.. As you clean up the Frame tube, the DEBRIS will fall Into The Bottom Bracket area... my advice is to Remove the Crank and Bottom Bracket! If you can't do this, then Lay the Bike On It's SIDE as you clean the rust out of the seat tube, then Empty the Seat tube frequently... and Do Not sand too much out,or your new seat post will slide right down in and be a pain to set correctly.. you can make a flapper sanding tool with a piece of 1/4" or 5/16" steel rod and a Hack saw with a fine tooth blade, 24 tpi or 32 tpi... and some 2" 120 grit Emery cloth strip from a hardware store. you'll need a hand drill too, but WAY easier. Just remove the outty rust, no need to polish every pit out of the inner surface... test frequently, dump debris frequently.
12-01-22, 12:55 PM
#32
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I am late to post to this party... Ha... I have not really considered a 1992 bicycle an old bike but looks like the time has come. So now it can be hard to find the proper seat post size on a 92 era bike. How time fly's. Just think of trying to find the seat post size of a 70s era bike after you have salvaged the frame from a junk pile. Yep, that's a challenge. Even if ya know what seat post is supposed to go into it. Here's the way I do it and remember its not "The Way but just A Way..."
Clean it up and sand it down inside and out
Give it an eye ball top to bottom
Is it round, inside diameter lower, inside diameter upper, fix what you can
Get a pipe and wrap tape around it to get the diameter that fits comfortably upper and lower
Use that diameter to get or make the seat post you need
Using sand paper to adjust the diameter of your seat post is no big deal if the seat tube has been properly cleaned and prepped
Don't forget to use a liberal amount of quality anti-seize compound from top to bottom on that seat tube before your final assembly
Hope to see you on the forum as ya go along and thanks for educating me that bikes made in the 90s are now having the same problems as those made in the 70s...
Give it an eye ball top to bottom
Is it round, inside diameter lower, inside diameter upper, fix what you can
Get a pipe and wrap tape around it to get the diameter that fits comfortably upper and lower
Use that diameter to get or make the seat post you need
Using sand paper to adjust the diameter of your seat post is no big deal if the seat tube has been properly cleaned and prepped
Don't forget to use a liberal amount of quality anti-seize compound from top to bottom on that seat tube before your final assembly
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12-01-22, 12:59 PM
#33
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Possibly, but these buggers can be pretty tough. Especially the ones made in Japan. Chances are it will be just fine. For a bottom bracket on a Mountain Bike I would prefer a Cartridge instead of loose balls. But still... Loose Balls Rule...
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Last edited by zandoval; 12-01-22 at 01:02 PM.
12-07-22, 10:42 AM
#34
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