I measured the rear dropout of the Redline frame I am planning to build up, and it measured 131mm. So I am assuming that the frame was designed to use 130mm hubs. But would it really kill the frame (and me) to try and use a wheel with a 135mm hub?

Not likely to be a problem in practice.

Sheldon "Springy" Brown

Alright, now let's bump this discussion up a notch - what if I was trying to use a disc brake setup? Would this change the position of the brake caliper relative to the rotor to a degree that would prevent such a setup from working?

Lord C.
You have gotten as definitive an answer as you can get on the 1st, but let me share my experience.
Most rear hubs have about 8-15 mm worth of spacers on the non drive side. Of course they are there for a reason-to keep the chainline right etc. However, if you aren't a mechanical perfectionist-(many members here are ,to their credit)-you can remove the spacer and replace it with some washers(take out 10mm replace with 6mm) etc, so you don't have to stretch the rear triangle.If it doesn't have a removeable spacer-and you don't care about using the wheel anywhere else-you can grind what spacer is there.
If you really really aren't a mechanical perfectionist you can fit 135 hubs on 126mm rear spacings.The wheel/cassette will be offset to the left 4mm, and the tire will be 4mm closer to the chainstays-there usually is enough room to accomodate this. The bikes still track true with hands off the bars-not sure why.
The above is strictly jury rigging to the max.I did this to put 26" MTB wheels/tires on a 1978 road frame. I use (95mm long reach) BMX brakes to reach the rims-a trick I picked up on Sheldon Browns site.The other abominations-cockeyed wheels- are strictly mine.
Luck,
Charlie

Charlie....I am confused....why would spreading 126 to 135 (either spreading or cold setting) cause the wheel and cassette to be offset. Wouldn't it still be centered between the now wider stays?

thanks

Squirtdad,
I was unclear. Instead of spreading the dropouts apart to fit a 135mm hub ,I narrow the hub by removing a spacer. Unfortunately the spacer is just on the non drive side,so everything is shifted to the left by 1/2 the width of spacer removed(shifted relative to a normal hub that was built to fit the spacing-)

Thanks,
Charlie.

Well, in answer to my second question, I took the front wheel off of my commuter (which is a mountain bike with slicks) AND the disc caliper, and mounted all of it on my Redline fork (the fork is loose). It fit pretty well, although the rotor was rubbing rather heavily on the outside brake pad. I am thinking that with a fully adjustable disc brake caliper, like an Avid BB7, 135mm would work on this build.

LordC,
If you didn't care much about that front wheel you could grind a bit off the right side nut or spacer on that hub,and shim(with thin washer) the left side to move the rotor a bit to the right.
I'm extremely wheel rich because of the 4 sets of Katrina wheels I have/am rehabbing-and the 10 other parts wheels- so I'm a bit to casual about destroying/modifying things.
Cheaper than a Avid 7, but selling the 5 and buying a 7 might be just a $30 difference. If the wheel/hub is nice you wouldn't do it.
When SB weighs in his advice is always the best and most considered from all angles-safety,cost, ease of doing etc.No surprise, he is a pro with decades of experience. Nice guy too-never any snide comments . Our/my advice usually involves some shortcomings- frequently with safety given short shrift.I'm a bit casual in terms of safety-I don't consider it enough.
Luck,
Charlie

I'm not a big expert on disc brakes, but generally you can use spacer washers betwixt the caliper and the mount to move it sideways when needed.

Sheldon "Not Even Sure If It's A 'c' Or a 'k'" Brown

So modern forks aren't all the same spacing, right? i.e. 100mm or something.