daviddavieboy

Has anyone here every rebuilt a frame to make it smaller, as in remove the lugs, shorten the tubes and re braze the frame? I am only interested in shortening the reach so it would involve removing the lugs on the headtube and lengthening the headtube. I have never done any sort of framebuilding before except if you count making a chopper as a kid in the 70's but am very good with other types of metalworking.(repairing/fabricating machinery) My concern comes from destroying a good quality frame and possibly creating dangerous handling.

Cynikal 

I would think that would be considerable more complicated than just building a frame from scratch.

Doug Fattic 

No it is not a practical thing to do and yes you would be most likely destroying a good frame. If it is a production instead of custom American frame it is probably brazed with brass which requires some special knowledge and skill to take apart successfully if the lugs are going to be used again.

That isn't to say it is an impossible task and if someone gave me an unlimited budget to make it happen I would most likely take off the whole front end and rebuilt that with 3 new tubes and head lugs. A rule of taking a frame apart is that you can't at the same time undo 2 places that have been brazed together. For example if you are removing a rear dropout you have to cut the dropout in several places so you undo the piece in the seat stay and then undo the part into the chain stay in 2 steps.

So to take your frame apart some tube has to have a section cut out in order to remove the other pieces. And then it is like trying to put Humpy Dumpy back to gather again. It is just easier to start with new pieces.

Andrew R Stewart 

Yes I have done this, due to a mistake on building the frame to the original specs initially. The frame was tall enough to have plenty of head tube remaining after I cut of fall the top head lug to fit a new top lug. (That the frame was designed with a very short top tube length made the resulting smaller size have a top tube length that was pretty much in the middle of common lengths for that smaller size). I removed the seat stays (don't remember if I reused the stays, sorry) and reattached stays to the now lowered seat lug.

Was this as time consuming as building a frame from scratch? No. This did allow me to end up with a good frame and remove the mistake I had made, although no longer for the rider I had intended it for. Did this repair/resizing take all the same skill set as building from scratch, yes.

Do I suggest this for others to do? Depends on why one wants to resize their frame, how much size reduction is needed and what their skill set/tooling/experience are. As usual Doug's reply make the most sense for most people most of the time.

Can you give us more details about these questions? I'll be happy to give the long story if asked. Enough to say that I learned far more about customers relations then frame building in this situation Andy

CliffordK

I think there was a thread somewhere about someone who inherited a frame from his father that was too large for him, had it disassembled and rebuilt for nostalgia. But doing so is rare.

In your case, if you are wanting to simply cut off the TT/DT and move the HT, that should be simple enough, but that will also lower the point of the bottom of the head tube. Thus, the frame will sit higher on the fork, and could potentially throw off all the other angles on the frame.

You could change the angle of the DT at the bottom bracket, but then you'll also be dealing with tire clearance issues which may or may not be an issue.

Going to a smaller front wheel like was done with some Terry and a few other vintage women's bikes would be an option to recover the original geometry with a shorter fork.

Before making the change, I'd carefully consider whether you can make adequate adjustments by going with a shorter stem, if reach is the only issue.

Perhaps get a "fitting" done to confirm your goal of a shorter reach.

Then start scouring frames for one with the dimensions that you wish.

One of the oddest short frames is the Gitane Traveler (or traveller). But, that frame also used a very long stem, and perhaps a few other optimizations to make up for the short length.

If this is all simply a frame size issue, many used frames are cheap.

unterhausen

the resized frame CliffordK did not have a good outcome as I recall. Pretty sure it was a Dick Nolan frame, which is a rare beast.

Dick Nolan was the engineer at Trek at the beginning. The picture they used a lot showed Dick and Mike Appel standing next to the fork threading machine. Dick is the guy on the right with the heavy beard. Other than some of the very early Treks, I don't think Dick made too many frames. I saw him making a tricycle, don't remember ever seeing it finished though. He was very meticulous.

Andrew R Stewart 

I see that the Op was talking about shortening the top tube length, not the vertical size. So my earlier reply isn't on topic. Not the first time I've been off topic

The Op's question is one with more issue then solution I feel. Andy

CliffordK

Thanks...

I just needed the right keyword for the search.

https://www.bikeforums.net/general-c...lve-issue.html

The resizing went well, but unfortunately there was a communication error, and the resized frame was smaller than desired, but still turned out good.

The original was a HUGE frame. I could imagine how its utility would be compromised for us mere mortals.

I'm not sure if there was any longterm followup.

Looking at that Nolan frame, I can see paint removal at every joint, so in that case, essentially the whole frame was rebuilt from scratch.

In the OP's case, if only the front of the frame is rebuilt, then at least the rear triangle would likely stay original which would reduce the work somewhat.

CliffordK

I'm all for multi-use tools. I've pretty much stopped carrying a separate chain tool after I've had the opportunity to test my muti-tool chain tool a couple of times.

I've started carrying one of these wheel shaped spoke wrenches.



It is one of the few wrenches that will handle the Shimano WH-RS10 nipples, and will generally work for whatever I ride, or if I encounter someone that needs some quick truing.

If the only reason to carry a cassette tool on the road is to replace spokes, then combining the two functions would seem reasonable.

A 15mm and 17mm socket would be nice for occasional use.

Perhaps an adapter for 1/4" tool bits (some power behind removing a pedal with an Allen wrench would be nice).

unterhausen

I am pretty sure the angle of the OP's downtube is going to be wrong. Maybe it can be bent into the right angle. It's a lot of work, much more work than building a new frame. With new head lugs and new head tube, it would be a bit less. Cut off the head tube by chopping the top and down tubes, hang the old headtube on the wall, and put it back together with new parts.

Good find on that Nolan frame thread. The final bike looks like it fits okay.

Andrew R Stewart 

Having bent seat and down tubes to close up the angle and resulting in a ripple on the seat tube (right down at the top of the BB shell) I wish the OP good luck in reangling the down tube. Andy

daviddavieboy

This is the process I was thinking.
1 - cut the head tube in the middle
2 - put the front of the frame in my forge or heat enough with torch to dislodge the lugs and do the same to the portion of the headtube left in the lugs
3 - clean clean clean
4 - cut and notch top tube and down tube approximately 3 cm
5 - fit components in a jig to keep the headtube in line with the seat tube
6 - tack in place let cool and check for alignment when released from jig
7 - re braze parts
8 - face the new head tube, send for chrome, re paint and build

The lugs have the angle built into them so shortening the two tubes will only cause the headtube to be longer and from my thinking the only change in geometry will be a non horizontal top tube and a slightly higher handlebar height (and of course shorter top and down tubes) This is not a bad thing as I am going on to 50 years old and not as limber as I once was. Keeping the rest of the bike intact insures that everything else should be in good alignment and a simple jig would be all that is needed to make the main triangle straight.

I have a old Bianchi that I don't really care about that I may experiment on first. I am sure of my abilities but this is old 531 and nervex lugs and quite concerned about ruining it. I realize that I could dismantle the whole front triangle and rebuild to properly size the bike but I was hoping to do the least destructive method.

Dancingbear

I encourage you to take the Bianchi you don't care about and go for it. Based on my own experiences disassembling lugged joints I strongly suspect that will put an end to this idea. Not trying to be negative or nasty, just a realist with some experience weighing in.

Andrew R Stewart 

I see that the OP lists chrome on his list of steps. Chrome is a big flag up the pole. If the frame already has chrome then that needs to be removed (chemically is far led damaging then mechanical removal) before any brazing is to be done. If the chrome is to be added after the modifications are done then care must be taken with the brazing to have no pocks or gaps (ask any English made Raleigh retailer about this) and to have thorough cleaning after plating to remove the corrosive cleaning agents.

Doing this kind of work on a frame can be much like a cancer. The resulting condition of the frame has less ability to handle further insults (like chrome) to the metal.

As to the actual headtube removal- No need to use any heat. Just cut down the down and top tubes a tad less then the intended shortening needs. File off any remaining lug tips, miter and reassemble with new lugs and head tube. Oh and don't forget to bend the down tube to keep the head tube's new bottom the same height off the ground. Keeping the head and seat tubes in plane will be the least of the problems...

I do like Dancingbear's suggestion to just do it. The Op might end up with egg on his face and learn why we don't encourage this type of job. Andy.

CliffordK

There are some frames that essentially put an S-curve into the downtube.



It might be easiest to bend the tube off the bike, then re-install.

Andrew R Stewart 

If you're going to pull the DT out of the shell then just reposition when reinstalling, no need for any bending. But this is an example of hoe these types of projects tend to expand in scope as you go along. Andy

dsaul

If you shorten the frame by 30mm, the head tube is going to be significantly longer. That length is going to be on the bottom of the head tube, so it will not just raise the handlebar height. It will raise the whole front end of the frame, changing the head tube angle, seat tube angle and bottom bracket drop. It will not be the same bike made shorter. It will be a completely different bike from a handling perspective.

Just put a short stem on it and ride it. The stem will effect handling far less than the change you propose.

Gresp15C

While unrelated to the OP, how hard would it be to replace the dropouts on a steel frame bike, i.e., convert vertical to horizontal or track ends? Can this be done with a mapp gas torch? I'm quite good at silver brazing (have done vacuum work and general repair of non bike related things) but have never put torch to bike.

Andrew R Stewart 

Gresp15C- Would you consider starting new thread? Andy

Gresp15C

Yes, thanks.

daviddavieboy

This is exactly the known unknown that I was wondering about and had not considered. I knew the head tube would need to be lengthened and as such would raise the front of the bike but I had not considered that it would throw off the center of gravity of the rider. I am on the hunt for a shorter stem but as of yet not found one. Anyone have a 80mm Jackson panto kicking around lol. To get it right the whole bike would need rebuilt and that is not a task I am into. I may as well start from scratch rather than do that.

CliffordK

80mm is a rather standard stem length. Certainly not unusual enough to wish to chop up a frame.

You can buy rather short stems if you need.

https://www.ebay.com/itm/Vintage-Sak...2/253980558513



With all the modern CNC work, you should be able to find someone to pantograph it. Etching?

But, you may find yourself a little short on real estate for your pantograph.

I think some drop bars also have a little less reach than others. Although, you may find yourself with compact bars and hunting for a 31.8mm stem.

https://www.ebay.com/itm/J-L-NOS-Thr...s/351784121927

https://www.ebay.com/itm/J-L-NOS-Thr...s/223209107505

Again, customize with the panto you wish. Perhaps if you buy 100, the Chinese company will customize to your needs.

wsteve464

Buy a stem adapter to 1 1/8th plenty of short threadless stems around in the 35-50mm range.

Road Fan

When I was looking for a nearby builder to replace the TT and DT of my crashed Mondonico, I posted on CR for opinions. Dale Brown replied that once Franklin Frames of Ohio had performed a frame resizing for him (for one of his customers), and he and the customer were very satisfied. I didn't seek out more details. I ended up going with another builder.

The discussion was far less detailed than this thread.