Originally Posted by
mtnbke
The idea of putting the faces of the BB shell in a vise gave me chills. Do NOT listen to that advice. You want to spread the chain stays apart, not dynamically bend the entire frame. The entire point of doing it right with a chain stay spreader is you get to choose and isolate where you are putting pressure on the tube set. By clamping at the BB you're risking popping a lug (if its a lugged steel bike) and you have no control over the "where" of the bending forces are applied. With butted tubing you want to introduce the least amount of force necessary to spread the chain stays, not the chains stays AND seat stays if that makes sense. Effectively you really end up doing both, but by focusing "where" the spreading force is applied it can be done right with the least amount of change to the frame. You don't want to over bend then correct. You can get the frame realigned when you do that, but it changes the way the frame rides introducing unbalanced spring rate to the stays.
....
Again, you can fit a 130mm hub into a 126mm bike without doing anything. It just makes getting the wheel in and out a bit trickier, ten more seconds at the most. Better than bending a frame in my book.
...I'm gonna go with you don't know what you're talkin' 'bout.
#justguessin '
While a spreader is a swell tool to have, simply inserting it between your chainstays and pushing those babies out against one another until you've gone far enough past the elastic limits to get them to stay at 130mm presumes that they will both spread evenly away from the centerline, which almost never is the case in real life.
Speaking of real life, how many of these have you done? Because I really have done quite a few at this point, and I don't give advice here unless I have some practical experience on using it successfully. That stuff about dynamically bending the entire frame really misses the point of what i so patiently and carefully explained, amigo.
