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How much can you safely change the rear spacing of a steel frame by cold setting? I have a frame with a 120mm spacing that I'd like to put a 5 speed drum brake hub in. The hubs I've found all have an over the locknut dimension around 130mm. Is it safe to go up that many sizes by cold setting, or should I settle for a 3 speed that just fits?

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Lord Brown deems it permissible. As to the question of how far is too far, I suspect the frame itself is equipped with an audible alert mechanism when the "too far" tolerances have been reached. 

I'd say it's OK if when you are done the tubes aren't kinked anywhere and nothing pops or cracks.   You won't know  until you do it.  But I've seen frames bent much further than this and then bent back.

If it were my bike I"d go for it. 

Just be sure you make sure the dropouts are aligned when you are done.  If you don't do that you'l have problems.   5mm each way is nothing though -barely moving it, but you will see a slight misalignment of the dropouts which will cause trouble with your wheel, and if you are running a derailleur  you'll be chasing issues all over the place trying to get it to shift smoothly.  It doesn't matter if you have an integrated hanger with the dropout or a claw -you'll have problems if you don't have it all aligned. 

It will be just fine.

If you want I can show you how to make a couple of tool that will do it evenly and with a measurable result as well as make sure it does not stress the brake or chain stay bridges  but just grabbing hold and doing your best strong man impersonation will be fine as well.

I use a 2x4 to pry outwards from the seat tube.  I've got a piece of wood that goes over the seat tube and bridges between the BB and the top of the seat tube so that the stress is  not going into the middle of the seat tube and maybe bending and/or kinking/denting it.

If you have a good metal ruler or a caliper (cheap plastic calipers from harbor freight work fine) you can spread each side the required amount carefully bending a little and checking, then bending a little more -so that you get the exact 5mm movement (in this case) on both sides.

I use a string to measure from one dropout  around the head tube and back to the other dropout.  A couple of rubber bands on the ends keeps equal tension on the string.  With this string you can measure off of the seat post to make sure the frame is aligned correctly to start with.

To check the dropout alighnment I use old axles (make sure they are not bent) cut in half.  You can get old axles from Working bikes for next to nothing.  

Here is a picture of what it looks like from one of my projects.  Here I was going from 126 to 130 on a CroMo Raleigh Pursuit 

That is before I even started.  Look how crooked the dropouts were.  Either they came that way from the factory or got tweaked by one of the previous owners.  The frame is a 1985 so who knows.

I guess I don't have a picture of what it looked afterward.   It was perfect and the OLD was 130.5mm to give me ease of putting the wheel in.

This is not rocket science -anyone can do it with minimal tools if they are careful and have a little bit of knowledge about bikes. 

Dear Notorioius,

     I'd like to know how to make the tools for cold setting an old steel frame.  Thanks.

Best, cnadon

notoriousDUG said:

It will be just fine.

If you want I can show you how to make a couple of tool that will do it evenly and with a measurable result as well as make sure it does not stress the brake or chain stay bridges  but just grabbing hold and doing your best strong man impersonation will be fine as well.

Sheldon's Method

Threaded Rod Method

I use a modified Sheldon Method because I don't like putting that much stress on an unsupported seat tube.  It can bend and be ruined if you lever too hard on it.   I put a brace from the bottom-bracket to the top of the seat tube to spread out the force. It's just a simple C-shaped piece of wood.

Some folks like the threaded-rod method but I have found using the string-test that the rear triangle often doesn't "give" evenly when it is spread and one side inevitably spreads more than the other -then you have to do the Sheldon method to even it out anyhow.  You might as well save your effort and just spread each side exactly half the distance and not over-bend and have to bend back, weakening the frame.  But there are others who disagree.  

Remember that you will have to align the dropouts again when you are done spreading the frame.  A simple axle cut in half is all the tool you really need for this job (shown on Sheldon's page in the first link) if you have a good eye although Park tools sells an expensive tool that does the same thing and makes it a little easier to do the bending. 

You need a clamp to go over the frame at the chain stay and seat stay bridge to prevent them getting stress on the joints.

Then use a turnbuckle with ends modified to clamp into the drop outs to spread it evenly and slowly.  Check it as you go and expand it slowly.  You will usually have to go past the dimension you need to account for spring back.

That's kinda what I was thinking... that in this case there is no need to cold set it at all. There should be enough play in the stays to just squeeze them apart when mounting the wheel?

notoriousDUG said:

It will be just fine.

If you want I can show you how to make a couple of tool that will do it evenly and with a measurable result as well as make sure it does not stress the brake or chain stay bridges  but just grabbing hold and doing your best strong man impersonation will be fine as well.

It can just be spread apart to get the wheel in but I think cold setting the frame is preferable for two reasons.  First of all it makes getting the wheel in/out/aligned/tight easier if the spacing fits the frame.  Second I think that it is less damaging to a frame to have it cold set properly than it is to have the wheel continually pulled apart or pressed in.

Picture yourself fixing a flat in the rain at night.  I used to deal with a too-long axle and squeezing the frame to fit.  It's a pain in the long run.

Tony Adams said:

That's kinda what I was thinking... that in this case there is no need to cold set it at all. There should be enough play in the stays to just squeeze them apart when mounting the wheel?

Thanks to all.  I used the all-thread method to expand the back spacing on an '86 Dave Scott Iron man to 135 mm. It could not have been easier.  Using the string test, I find that I'm now 1 mm off to the left when measuring from the string to the seat post (35 left, 34 right).  Is it worth the effort to try to bend it back just .5 mm using a 2x4, or is this close enough for my weekend-rider-purposes?

Again, my appreciation for the help.

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