MightyLegnano

Hello!

Do you have any experience with cold setting, any advice? What should I be careful about? Is it risky?

Thanks

Airburst

I've cold-set two frames. All I can say is use the technique detailed here. Just using a section of threaded rod, some nuts, and some washers to do it is a bad idea, because you'll probably spread one side more than the other.

dabac

I've done it a couple of times, using a slight variation of the method Sheldon Brown suggests. I put the frame on a workbench, with rear stays protruding over the edge, then the lever facing forward. I also keep the string in place to be able to monitor progress as I work. Don't want to overshoot and have to bend back.

Different frames have very different amounts of spring back, so one really has to check the result frequently. And preferably have some sort of stroke gauge to provide some indication of how much bend you should be using.

So far, no issues. Some have reported popping off brake bridges.

cny-bikeman

As long as it's a conventional steel frame and you're moving each side a reasonable amount (even 10mm is safe, and usually not that much is necessary) don't worry about. Just do it with a reasonable amount of care. I straightened dozens of rear triangles in my career without any problem. As noted above there is plenty of information on technique and tools found with a simple search.

SortaGrey

Don't bother. Set that rear in there.. spread with your fingers and insert. 'Cold setting' is just slang for 'could f it up'.

Airburst

The issue with that is that the dropouts won't be parallel, which isn't particularly good for the bearings in any hub, and is a very bad thing with any kind of internally-geared hub. Properly cold-setting a frame involves aligning the dropouts afterwards.

It all depends on the distances involved, a 130mm OLD hub in a 127mm frame isn't going to be a problem even if you don't cold-set, but things get iffy going for bigger differences than that.

davidad

And if you spread it to install the wheel you put a bending stress on the axle and shorten the bearing life of the hub.

Bianchigirll 

I personally never coldset a frame but I have had it done to a few. However I do agree that while just pusing the wheel in works the drops not being parrellel can be hard on the axle esp 7 or 8spd spaced FW ones.

SortaGrey

SO.. a random cold setting is so much more accurate for parallel? C'mon.....

I've run several larger into steels.. the tires track same. No problem.

Airburst

No, you bend the dropouts parallel again as a separate operation to spreading the frame, and you don't cold-set randomly, you follow the instructions on Sheldon's page to measure how much you've spread the frame. Tyre tracking is not the issue with non-parallel dropouts anyway, it's the fact that the axle gets stressed in bending when you do up the axle nuts.

well biked

I've cold set a few frames, including a couple of my own that I've ridden for thousands of trouble free miles afterwards. With most steel frames, it's really not a big deal. I believe that Sheldon's method, using lumber, string, careful measuring, etc is the best DIY method if you want to do it right and assure that the frame is in good alignment when you are finished. In most cases the dropout alignment issue is not a big concern.....as Sheldon points out in his article, the amount of misalignment caused by, say, a 126 to 130 spread is so small it won't really matter, especially since the misalignment is in the orientation that would cause the least harm to the axle/bearings. For something like, 126 to 135, I'd recommend re-aligning the dropouts in most cases.

I've ridden a bike that I cold set from 126 to 135, and it had relatively thin, stamped dropouts, and I didn't re-align them and it was a non-issue after years of riding. The stamped dropouts tend to re-align when the wheel is in the frame with the pressure of a good skewer anyway.

Cold setting is nothing to get psyched out about. Just take your time and be careful in how you do it. It's no biggie with most steel frames. Again, I like Sheldon's instructions.

FBinNY 

Ideally the OP should re-square the dropouts, but it isn't critical if spreading the frame 6mm (total) or less.

That much change in angle is barely discernible with the more common drop out alignment gauges. It's probably about as close as the bulk of the bikes sold new.

Reminder to the OP. You didn't say, but if this is not a steel frame, it's 100% a no go. Otherwise, it's almost too easy, (I've done dozens) and there's not much that can go wrong.

3alarmer 

I've done maybe half a dozen, but prefer not to if at all possible.

Personally, I'd rather just run the wheel in there that the frame was designed for, and
have, in the past with used bikes that came to me with rear hub and frame widths
mismatched, just built up the appropriate wheels.

But it is, as stated by others here, easily done with the proper technique.

I clamp the bare BB shell in a large bench vise on a solid bench attached to the wall
with the BB shell protected by wood or soft jaws from the vise. Set up your magic
measuring string from the same point on one rear dropout to it's fellow on the other side,
going around the head tube, and mark two spots to measure from string to seat tube
on the tube itself, which should be opposite and at the closest point of tube to string.

Measure with the depth gauge of a vernier caliper......even the two dollar plastic ones
from Harbor Freight work well enough.


We have one of those Park frame bending thingies at the coop, but it's not hard to
improvise something using scrap lumber.



I don't get the Sheldon Brown method, as it seems to me very problematic to
measure your progress on each side as you go along.



Interestingly enough, if you buy a lot of used bikes or work on them, they alignment
is very often off when you get them, so in my opinion, those are fair game for setting
them at whatever width you prefer as you straighten them.

pdlamb

I cold set one frame, but I thought the dropout alignment was close enough that I didn't need to worry with it. And I was right; until the dropout broke a few years later.

No problem with the cold set itself -- big 2x4 makes a great lever. Just make sure you re-set the dropouts.

pierce

i cold set my kids 1983 trek tx series frame which was meant for 120mm 5/6 sp. hubs so it would fit a 135mm hub (hey, we had a nice set of 36H wheels built on Deore hubs with MA40 rims and doublebutted DT spokes, were way too nice to waste). thats about as extreme as it gets, the long thin stays on that frame were visibly curved afterwards. I aligned the dropouts by eye using a mondo big crescent wrench, then brought it into a LBS who had the fancy Park frame alignment tool which showed it to be close enough for jazz.

I used the 2x4 on the floor and string alignment method pretty much straight off sheldon's webpile.

MightyLegnano

Thanks a lot for your answers, it really made it clear to me. What about dropouts alignment? Why cant I use rod and nuts? The special tool is so damn expensive

FBinNY 

You can't use a rod and nuts with horizontal dropouts. The key isn't whether they meet in the middle, but whether the faces are parallel, and a rod can't tell you that. The expensive tool, has large cups that you line up and look to see if the gap between is the same width all the way around.

I'd either pass on this step, or pay a shop a few bucks to do it right. That will be way less expensive than the tool.

Andrew R Stewart 

Drop out alignment will only make the drop out surfaces parallel to each other. This is needed to insure that there are no extra stresses placed on the axle/bearings. depending on the axle, bearings and frame there can be some bending to the axle in the drops are not parallel. This bending can have secondary ill effects. Drop out aligning tools are inserted into each slot and have surfaces that locate close to each other and allow one to visualize how they relate to each other. You can make some easily enough from a spare QR axle with cones and lock nuts. Cut the axle in half lengthwise, thread on the cones enough so that the axle halfs will fit into the slots with a little bit extending outside the drops. Thread on the lock nuts. What you now have are two hollow tubes that almost but not quite touch each other and each is square with their drop out. By sighting through the hollows you will be able to see how each axle tube aligns with the other. You can slide in a skewer to see how it goes into the further tube. When the drops are parallel (making sure the axle tubes are in the same spot in the slots) you'll be able to sight through the two tubes completely or be able to slide the QR skewer through the tubes with out it's hanging up or having to bend a bit. To do the actual straightening you will likely want to remove the axle tube and use either a large crescent wrench (making sure to engage the entire drop out axle surfaces) or a all thread rod with washers. Using the axle tube might distort the lock nuts as they are usually fairly thin.

One aspect of spreading that I don't think has been mentioned (I may have missed it in another reply, sorry if I did. I hate repeating other's comments) is that simply spreading both sides of the rear triangle at the same time will not insure that it stays in line with the main frame (if it was actually in line to start with). many frames, especially lower cost or older ones) have the chain stays dimpled for tire clearance but only the RH one for chain ring clearance. So it's not uncommon to have the RH stays move sooner and further then the LH side.

If you brought in the frame to my work to have it spread we'd charge about $35+ depending on factors yet to be discovered. The frame would need to be fully stripped for the lower end of the cost range to apply (it's easier to do with the BB out). And we'd want the wheel that was going into the frame with it. If you did the spreading and only needed the drop outs aligned then the bike could be built up with out effecting the cost, maybe about $10+. Andy.

MightyLegnano

Can't you simulate that with a big nut or something?

FBinNY 

Yes and no. It's a question of accuracy. Assuming you spread a frame 6mm (3mm per side) that would create an angle change with a sine of 3/300mm or 0.01 (300mm chainstay for easy math). So you'd need truly flat and aligned nuts (not common) and then assuming an OD of 1" or so, you have a gap change roughly 1/100th (.25mm) of an inch between the rims.

That's a lot of accuracy to expect a crude system.

Of course, my post assumes that the dropouts were parallel to start. If not, then you can use Andrew Stewarts method, or a modified version of the 2 bolt method to get them fairly close.

When I align dropouts, I use a tool with precisely ground 60mm diameter faces which I bring to with 1mm of each other. That makes small errors fairly obvious.

Andrew R Stewart 

"When I align dropouts, I use a tool with precisely ground 60mm diameter faces which I bring to with 1mm of each other. That makes small errors fairly obvious"-- FBinNY

As i do. But when I started out building the shop my mentor had was under funded. So we made do with home cobbed tools and methods. With good practice good stuff can come from simple tools. I'm happy to share soultions that I've learned, even if I have moved on long since. Andy.

FBinNY 

I agree that carefully done, your hollow axle method would work. But I don't think it will be accurate enough for the specific application of resolving an error this small (if it was parallel to start).

I'm all for improvised tools and low cost solutions, and am constantly impressed at how much many non pros on this forum have invested in tools. I've used similar improvised solutions for on the road emergency repairs, but for the specific situation here, feel that the combination of the OPs inexperience and lack of specific tools makes this a case where he's best leaving bad enough alone.

Doohickie

Depends how much you're going for. If you're just trying to stretch a 120 spacing to 126, I wouldn't worry about asymmetry too much. Even if you only bend one side, you'd only be 3 mm off, about 1/8 inch.

well biked

The thing is, by using Sheldon's method, taking your time a bit, you can assure that it is well aligned, maybe better than new. For me, it's worth that little bit of extra effort, but to each their own. We've got some frame alignment tools here at the shop, and I've certainly seen frames that had been cold set where only one side of the rear triangle bent, taking the frame out of alignment a bit. Again, to each their own, but I think it's worth following Sheldon's instructions.

FBinNY 

I hate to challenge Mr. Brown who cannot defend himself, but this method will not work for horizontal dropouts because there's no way to assure that rods in fact form a straight line. Imagine an angle with 2 lines coming off each leg at right angles. They can meet in the middle forming a diamond shape despite not forming a straight line.

Andrew Stewart's method with a hollow axle offers the possibility of ensuring a straight line meeting, via sighting the tube, or using a QR skewer, but is limited by the sloppiness of all the fits involved.