Spreading rear dropouts.

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Vetus Ossa
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Spreading rear dropouts.

Post by Vetus Ossa »

Me again, with another question about my new (quite old) frame.
The rear ends are spaced at 114mm, and I want to open them out by possibly 8mm, should I be afeared?
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Tigerbiten
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Re: Spreading rear dropouts.

Post by Tigerbiten »

If it's an old steel frame then you can "cold set" it.
Google search "cold set bicycle frame" on how to do it.

An other frame material is very iffy.
They tend to crack rather than bend.

Luck ........... :D
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andrew_s
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Re: Spreading rear dropouts.

Post by andrew_s »

Tigerbiten wrote: 4 Dec 2021, 11:52am Google search "cold set bicycle frame" on how to do it.
A lot of people just use a threaded rod and some nuts to jack the dropouts apart, but this method makes the assumption that both chainstays will bend equally. If they don't you've then the problem of putting the tracking right.
A common reason for them not to bend equally is if there's a dimple in the driveside chanstay for chainring clearance.

I'd suggest the Sheldon method
KM2
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Re: Spreading rear dropouts.

Post by KM2 »

You can’t cold set Reynolds 753,
If you use the threaded rod method above, why not clamp bracket in the workmate and clamp the threaded rod in position so you can judge the movement, as said above the gear side chainstay is more likely to move if indented for both tyre and chainset.
PT1029
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Re: Spreading rear dropouts.

Post by PT1029 »

Agree that simply spreading the dropouts might result in one side bending out more than the other.
The method on Sheldon Brown (as mentioned up thread) is to work out how many mm each side needs to move out, then spread one side first, then the other side after: -
https://sheldonbrown.com/frame-spacing.html ...... and scroll down to "Spreading the frame".

Don't forget to
1. Check the final result is symetrically spread drop outs (further down the above link)
2. The spread dropouts are parallel (simple bending the stays out leaves the drop outs slightly non - parallel, which means when you fit a wheel the axle and the dropouts are under a constant bending tension, risk of bent axles/cracked dropouts). See Sheldon Brown here : -
https://sheldonbrown.com/forkend-alignment.html

With some trepidation I used this method to spread my tourer from 126mm to 135mm rear spacing (and it had previously been spread from 120 to 126mm).
Rather a big jump, but I was happy to do this after in previous thread on frame spacing Chris Juden said Mercian were happy to spread his tandem from 120 to 135mm in one go.

Agree you can't spread 753. Springing a frame can give a clue to quality. Spreading a cheap steel frame is much easier that spreading a Nottingham made steel Raleigh.
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Vetus Ossa
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Re: Spreading rear dropouts.

Post by Vetus Ossa »

Hmm, actually I was planning on using the threaded rod method but can see that may not be the way to go.
To be honest those pictures of the Sheldon Brown method has always scared me a little, but think I need to read through that again.
Agree what has been said about 753, I had one and the rear dropouts were definitely staying where they were brazed.
This frame is 531 though.
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Audax67
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Re: Spreading rear dropouts.

Post by Audax67 »

I innocently reinvented the threaded rod method years ago and applied it to an old MTB frame, taking it from 130 to 135 mm. It worked, but judging from much that I've read since I was very lucky. Early 90s MTB frames make great tourers, BTW, if you can spread them successfully.

Did it years before that to get a 7-spd wheel into a 5-spd frame but used a lever, stout fencing wire and a Spanish windlass, doing one side at a time. That was OK too but it seemed to me that the frame relaxed back a bit after I put the wheel in: next time I had a flat I had to work hard to get the wheel out. (Crikey, those were 18mm tyres. How things change...)
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Norman H
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Re: Spreading rear dropouts.

Post by Norman H »

If I valued the frame I'd have the job done professionally. I was happy to reset a hack frame using the SB method but I entrusted my Dave Yates to Winston Vaz at Varona Frameworks. I was charged £25, which included realigning the dropouts.

Incidentally if you go down the DIY route you can improvise a dropout alignment tool using two lengths of 10mm studding and some lock nuts and penny washers.
mattsccm
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Re: Spreading rear dropouts.

Post by mattsccm »

Too much fuss. Just grasp each drop out in a hand and pull them apart. You'll need to go a bit over as they spring apart. Chances of your arms pulling different amounts are minimal unless you are injured/deformed. Maybe need to straighten the dropouts but probably not. Done this dozens of times over past 40 years.
scottg
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Re: Spreading rear dropouts.

Post by scottg »

mattsccm wrote: 4 Dec 2021, 8:30pm Too much fuss. Just grasp each drop out in a hand and pull them apart.[snip]
If you're not up to the one arm method, put the frame on the floor on it's side,
put your foot on the drop out, use both arms to pull up. Flip the frame over and repeat.
Do make the drop outs parallel, I used a 18in adjustable spanner.
3 parallel chalked lines on the floor can be used to establish centers & symmetry.
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Vetus Ossa
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Re: Spreading rear dropouts.

Post by Vetus Ossa »

scottg wrote: 4 Dec 2021, 8:53pm
mattsccm wrote: 4 Dec 2021, 8:30pm Too much fuss. Just grasp each drop out in a hand and pull them apart.[snip]
If you're not up to the one arm method, put the frame on the floor on it's side,
put your foot on the drop out, use both arms to pull up. Flip the frame over and repeat.
Do make the drop outs parallel, I used a 18in adjustable spanner.
3 parallel chalked lines on the floor can be used to establish centers & symmetry.
Thanks, more or less my plan, apart from using my arms, will go with the threaded rod :)
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slowster
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Re: Spreading rear dropouts.

Post by slowster »

A professional doing it to the rear triangle after replacing the chainstays:

https://youtu.be/PlJCzbARIeY?list=PLUJn ... f-V&t=1689
Stradageek
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Re: Spreading rear dropouts.

Post by Stradageek »

I do this regularly but the other way round. I've converted a number of old steel MTB's to SA 3-speed town bikes bringing the dropouts in to 117mm using the aforementioned large bits of wood. :D
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531colin
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Re: Spreading rear dropouts.

Post by 531colin »

1.....Check whether or not the frame is straight currently. You can do this with nothing more complex than a pair of properly built wheels and a piece of string. (Too good to lose! viewtopic.php?f=5&t=59332 )
2..... work out how far you need to pull out each dropout. Do them separately; if you do them together then usually the right dropout will come out further than the left, because only the right chainstay is dented to clear the chainwheel.
3.....To pull out one dropout at a time; You need 2 bits of wood and a concrete base. The seat tube rests on one bit of wood, the head tube rests on the other bit. The dropouts should be off the ground. Stand with your "best" foot on the seat tube, the other foot on the head tube, and pull out the top dropout by hand. You will feel the difference when the stays reach their limit of flexing and start to yield; don't go mad, do a bit at a time and measure the dropout distance to check how far it has come.
4....turn it over and do the second dropout
5....check its in track again....check dropouts are parallel

One last piece of advice.....build it up and ride it before you splash the cash on a respray or fancy parts; it may not turn out to be your hearts desire!
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Mick F
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Re: Spreading rear dropouts.

Post by Mick F »

I've spread a couple of steel frames, and compressed another one.

Mrs Mick F's Elsewick Mixte, and Daughter 2's Dawes Galaxy Mixte.
Mixte are harder as they have a stronger rear, but it was easily done with a threaded rod and nuts and big washers.
Both from 126mm to 130mm

The compression, I did on my Moulton to get it down to 130mm. Very VERY hard, but it was and remains fine.
The original spacing was 132.5mm or thereabouts as a "compromise" for 130 and 135. This compromise gives the worst of both worlds. Too wide to allow correct use of a QR with 130mm and too narrow for easy insertion of a 135mm wheel.

I compressed it as a reverse of the spreading - tightening inwards rather than stretching outwards.
Mick F. Cornwall
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