This blog doesn't bring you here to hear my opinions on nicknames, you come here to look for the glaring grammatical errors that surround my bike prose - and presumably you want to know something about bikes.
Today I'm going to explain how to spread dropouts on a steel frame. There is plenty of info out there that is written down, but not nearly as much with pictures, so hopefully what I do here will help someone else.
When I was doing my research on the NuVinci hub, I noticed that It was 135mm wide - and when I measured the frame I planned to install it in, the dropouts measured 130. I waited to get the hub before I made any changes to the frame, hoping that I could muscle the extra 2.5mm on each side.
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| That's a big hub right there - but not as big as the old version. |
Since you are reading a post about cold setting a bicycle frame, I'm pretty sure you figured out that I am a noodle armed weakling and couldn't make it work. I needed to to widen the dropouts in order to install the wheel, and I decided to bring you along. Cold setting isn't particularly hard, you just have to be careful. This is the second time I've done it; the first time was to allow my Falcon to accept a modern Freehub rear wheel.
Before I go any further, I just want to say that if you follow these instructions, it is at your own risk. Do not try to set any frame other than steel, and to be honest, you probably shouldn't even do that based on my advice. If you choose to follow me it is at your own risk.
First, you will need a long piece of allthread. This is available at your local hardware store, along with the nuts and washers you will need. Buy four nuts and 4 washers. I like to use 4 because I feel like it helps to distribute the force to the dropouts evenly. The other nuts are so you can keep track of your washers.
This homemade tool can also double as a headset press if you buy a long enough piece of allthread.
You will also need a digital caliper or some other measuring device.
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| This tool cost like $4.00 |
Put the nuts and washers onto the allthread. Nuts first, then washers.
(It's the opposite way to press in a headset.)
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| Threaded. |
Put into dropouts and snug the nuts against the washers. Finger tight only.
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| Make a mark on the thread and the nut so you know how many rotations you have made |
Use two crescent wrenches to make sure you are making the turns equal.
Next step, turn. Make sure you turn each nut equally. Turn right side, then turn left. Repeat.
After about 5 equal turns on each side, I measure again. It often takes fewer turns that you think, so check often. For me, 2.5mm on each side took approximately 25 turns.
And that is really all it takes to cold set a steel bicycle frame. Careful measurement is important, because you don't want to go over the size you need and then go back - that is unnesscesary stress on the rear stays.
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| Like a glove |
I don't think that cold setting a frame is a bad modification to make to an older bike. I feel like it's an easily reversible change, and generally we are only talking a few millimeters of change. There are many really nice older steel frames out there, and cold setting gives you the option to build the bike with a modern drivetrain.
I just used this method, although turning nuts equal amounts won't prevent misalignment with the frame. DS would always be slightly farther from centreline than NDS. Tried swapping DS nut to outside of dropout then tightening back in, nearly solved but required tweaking by opening out again then using wooden post between inside NDS dropout triangle and seat post section of frame to lever out. Success! However, having said this, threaded rod method is gradual with better control for the majority of the job.
ReplyDeleteSorry you weren't aligned - I check using the string method, and haven't had alignment issues with this method. Perhaps your frame was out of alignment to begin with.
ReplyDeleteWhy not cut the all thread in half and put a turnbuckle in the middle - then you turn one wrench and know you are expanding equally.
ReplyDeleteYou then need a really good turnbuckle (so it's all solid and not misaligned), turnbuckles are generally for tension not compressing (here you compress it), and most importantly YOU NEED A LH THREAD on one of the all thread, and a normal RH thread on the other one (this is not the problem but the LH thread is very hard to find on all treads)
ReplyDeleteWhile cutting and turnbuckling seems like an interesting idea, part of the appeal to just using all thread is that it is available, simple, and easy for the average person who may want to do this once or twice; if you are so hardcore that you want to make a specialty tool, just buy the right tool for the job.
ReplyDeleteso i plan to cold set my steel track frame (110 spacing to 120). i currently have made a 120mm wide hub/wheel fit by pulling open the stays to allow it to fit. my question is - how is this method any different than doing what i did in terms of permanance? putting a 120 hub in the 110 spaced dropouts is pushing it open, but it doesn't stay that way once the wheel is removed (and a quite difficult task at that), so how does your method make the spacing permanent?
ReplyDeleteThis method actually stretches the metal permanently - because you exert steady pressure on it beyond the stresses of pulling it apart by hand. I'm no metallurgist, so "magic" is the short answer.
DeleteI am a 43 year old that is getting back into building and restoring old bikes after 25 years of hiatus. I was never one to leave well enough alone. I have done both types of cold press and found out the using the combo method is the best(in my opinion)way to go. Like the gentleman said, the turnbuckle idea seems to be a good one but you would need a piece of reverse thread allthread and the turn buckle would have to be a a high end piece. If your going that route, might as well by a tool made for that. I am currently cold pressing an old schwinn beach single speed cruiser. The thrill of this is that once your done your project becomes one of a kind. Being in south Florida there is a good chance you'll run into your bikes twin so little mods like this are what makes your wheels unique......Started rambling....SORRY
ReplyDeleteShoot... I just take a 2X4 and use it as a prybar. I also stretch taut string around the head tube and to each drop out - measure from the seat tube to string to check for equal spacing. I've stretched frames further than you did and even pried them back if I went too far... no issues although I agree that in theory it's better to take it slow and steady and not backtrack. What do you feel is a reasonable tolerance as far as equal distance from the seatube to the string? I.E. +/- a couple of millimeters doesn't seem like it would make a huge difference in 'real world' riding. I suspect I flex my frame more than that while riding.
ReplyDeleteHi and thanks for all these informations.
ReplyDeleteI need to cold set my steel frame from 130 mm to 110 mm.
Do that method works in the opposite direction, to reduce spacing ?
I finally did the trick and that works properly... I am respace at 110 and all is symmetric. You have to be patient and precise in movements of tool and millimeter after millimeter you win the need spacing !
DeleteI just hope my frame won't break in 6 month :)
Many thanks for the trick, I was hopeless to fit my new wheel !
Hello.
ReplyDeleteIs there a certain amount of time you should leave the allthread in place before the cold-setting will 'take'?
I've just tried this technique out on an old MTB frame I'm trying to spread from 130mm to 135mm. It seemed to work a treat, as I turned the nuts (only took about half a dozen full turns) and got the 5mm I required. I actually left the tool in there for almost two days, as I got distracted before I could return to it. But as soon as I unscrewed the nuts, the drop-outs found their way back to 130mm.
I'm pretty sure the frame is steel (it passes the magnet test). It used actually to have a 126mm hub bolted in there real tight, but I'm not sure whether that has anything to do with it. Any idea what's going wrong?
Cheers
Hally
Harry,
ReplyDeleteYou have to go beyond the point of elasticity of the steel or yield point so it won't return back to its old position. Just moving the stays out to the exact point of measurement is not sufficient. You have to go further and then remove and check. Doing this will make it permanent.
Ahhhh, GOTCHA!
ReplyDeleteHi, would this work with front forks as well? I only need 3mm either side.
ReplyDeleteIt's been my experience that the all-thread method works really well for forks because the blades are symmetrical and each side will bend the same. 3mm a side (6mm total) is right on the edge of needing to re-align the dropouts so the axle doesn't bow when tightened.
DeleteThe all-thread method assumes that each chainstay will deform symmetrically. Esp in the case of older frames, this isn't true. Usually the right side chainstay isn't as stiff due to the dimpling to make room for the chainring. So using the all-thread method makes the right side chainstay do most/all the movement/setting, the left side stay in place. That will cause the frame to be mis-aligned.
ReplyDeleteIf I'm spacing from 120mm to 135mm I move one side 7.5mm first, then the other side. I check the dropout alignment (with h-tools) after moving one side and re-align the dropout to the un-moved side keeping the proper reference to the center of the seat tube.
To hold the frame in place, I use a bench vise and wooden blocks to hold the bottom bracket between the faces (with the frame upright). Then I can really lean into the stays and move them cleanly. I have found that adding in more than ~5mm of spacing will require the dropouts to be re-aligned with h-tools or a big wrench and a good eye.
I have a 126mm dropout frame and run a 130mm hub and I'm happy at the moment to wrestle the wheel in. I ride Marathon Plus tyres to reduce the risk of this happening at the roadside. However I have long had the idea of cold setting the frame (by your method) in mind.
ReplyDeleteOne thing though ... surely it wouldn't matter if you did all your turning with one nut. There's no need to turn the nuts equally. The threaded bar will press exactly equally against both dropouts; a turn of the nut will push the threaded bar back against the opposite dropout exactly as much as it pushes the washer forward on the near one. It would only matter if the bar was anchored in some way to the rest of the frame.
It's the fact that the force is equal on both chainstays that might result in the DS stay bending more due to the dimple (that Eric the IGHer refers to above).
That said, if I ever do decide to do this, I will turn both nuts equally. Having first knocked on wood.
Thanks for an interesting post.
- To take a cold set (technically to plastically deform) the stays, they first must be taken past their elastic limit (by definition the limit beyond which a material won't return to just very slightly past its original position). All deformation beyond that point will be permanent. It is more likely than not that one stay will bend farther than the other when equally stressed (as this method does), so work in steps and near the end consider taking a lever or rubber mallet to one side at a time. A frame alignment gauging method is essential.
ReplyDelete- This method as presented will stress the chain stay and seat stay bridges during the bending process and in addition will leave residual stresses in these joints if any of the plastic deformation of the stays occurred at the bridges - there is some risk these joints could fail either during the operation or later. This risk can be reduced by clamping the tubing at the stays (overlapping a bit closer to the drop outs) with appropriately grooved and padded blocks. Avoid squashing the tubing by over tightening the clamps.
- One must reset the parallelism of the drop outs when done, non-parallel dropouts generate a bending stress that damages hub axles.
I'd like to know if you can make 130mm to 150mm or would that be to much?
ReplyDelete