Branimir

So, here's what happened:




You can see the top and down tube got a "belly".

Is it possible to straighten it out via HTS-1 similar method - I've searched the forums and saw salvaged Peugoet and some others...

Thanks.

cny-bikeman

You might want to just leave it, unless the fork interferes badly with the pedals or if the handling is squirrely. but there's no guarantee the fork is not bent - to one side or one blade back more than the other. It's possible to do it with that tool if you know someone who has it, but THIS TOOL IS NOT FOR USE ON FRAMES WITH AIR-HARDENED STEEL TUBING, e.g. Reynolds 753, 853; True Temper OX, etc.

Branimir

The fork is bent, but I could go with replacing the fork... Though I find it hard to part with the frame...

Andrew R Stewart 

Branimir- People do a lot of things to old and bent bikes for a lot of reasons. Not all are what might be considered "best choices". Don't base your decission of what you see on line. You should take your bike to someone who has experience with this kind of damage. They will be able to discern the whole picture and give you a better understanding to what should be done.

You're photos show some bending of the frame and fork in a rearwards direction. But not whether there's a side/twisting component. Is the fork's steerer bent or just the blades? Do you know the original head angle or front center? It's not hard to bend the frame/fork into a new place but hard to know if this new place is where it was before the incident.

The best repair would be to replace the TT, DT and HT with a new fork. This way all could be tied into a compatible design, geometry wise. And no residual stresses or weakenesses would remain. But still no insurance of perfectly duplicating the geometry. And the cost would be high.

All your solutions have their judgements to be happy with, good luck. Andy.

FBinNY 

+1, leave it alone, it's only slightly bent and will probably ride fine with a new fork. A skilled mechanic might be able to improve it, but you're better off leaving bad enough alone.

This was very common back in the day, and bikes like this could be ridden for years in this condition, but it's a permanent weak spot, and eventually the tubing will fatigue there. The bright side is that these frames are very polite and take a long time to finally let go, and will give you fair notice with visible crack formation starting at the ripple, and slowly over hours, days or even weeks propagating around the tube before it finally lets go.

Branimir

Okay thanks for your comments. I cannot notice if bent made notable changes to the geometry, maybe a couple of mm's.

I'll probably leave it as is, use it for commuting, and avoid any serious stress to the bicycle, rather than to try to straighten it up.

Cheers,

B.

Branimir

Sorry for bumping this topic up, but it seems I've found a person that repairs steel bicycles, actually changes tubes, still trying to contact him and appoint for repair, since he's in Slovenia, but luckily, only 80km away from here...

A question for builders/experts:

In this case the top and downtube are damaged, so that means they should be replaced - is it possible to alter the size of the frame while doing this, while keeping the geometry? Actually what I mean - for the repair expert who's replacing the tubes - to also take out the seat tube and shorten all three of them to keep the geometry, just to reduce size. Top tube is now something like 55.5cm, seat tube C-T is 56, and I was wondering, if he's pulling out top and down tube, why now seat tube and then make it 2cm shorter on those measures also (top tube and C-T), the bike would fit me a bitt better

Is this doable/common practice/etc?

Thanks!

cny-bikeman

Smart move

Not so smart move...

The tubes are only slightly bent - they have very little chance of failing, are unlikely to affect you significantly.

Anything is doable. but to travel 80 km to have the main triangle on a low-end bike rebuilt (after which it will need painting as well) does not make sense. You would likely spend more on that process than by throwing out the bike and starting over, and you STILL don't know if the fork is bent to the side.

Common practice would be to buy a bike that fits you that is not damaged.

FBinNY 

Anything is possible, but you're passing the point where a new frame, custom built would be less expensive and simpler. Shortening the seat tube means lowering the seat lug. That means cutting and shortening the 2 seat stays, and angling them a bit lower, so possibly both seatstay/dropout joints would need rework.

Now the only thing left untouched is the bottom bracket/seat tube joint both ends of the two chainstays.

When you figure the extra labor of taking a joint apart, which os often harder than brazing was, you're looking at a big bill.

I'd either leave this alone and ride it as is, or do the minimum necessary. Otherwise talk to the builder in Slovenia about starting fresh, based on this bike as modified for you.

Branimir

Uh, silly me, I forgot about the seat stays! Yes, makes sense, it's too much hassle, though - a new frame, would be a much wiser idea... certainly not money waisting...

Btw the fork IS bent, don't know if it's fixable, or should I search for a new one...

And I lost an ebay auction on an Columbus SLX frame, that went for 159 euros on italian ebay with 20euro shipping to here... I stopped at 152... oh well...

FBinNY 

Steel forks can be straightened, but it depends on the location and severity of the bend. I think it might make sense to visit the guy in Slovenia, and bring the frame for a consult, plur to talk about other options.

As for your lost shot on ebay, there's be others.

miamijim

I had a frameset with similar visible damage awhile back and the head tube angle measured with 'spec'. I dont know what the original angle was so I looked up what it might be by comparing various geometry table and what I measured was close enough not to bother tinkering with. Steel is unique in that it springs back a touch after an impact which expains why you'll see damage without a compromise in head tube angle.

Another way to check is to measure the wheelbase and chain stay lengths. A typical road race wheel base may bee 1005mm with chainstays of 400mm which means the distance from the BB center to fork ends would be 605mm.

go through a bunch of old frame geometry charts and calculate average dimensions of what similar frame sizes to your have and measure yours in comparison.

Andrew R Stewart 

Not sure about trusting the charts for any one bike. I know of many small but real differences from claimed specs to the actual ones. Also if a tube has a ripple in it after an impact then the length on that part of the tube has changed. Unless you're saying that the tube stretched so the ripple could exist and the angle not change. Not likely, espically with the ripple on the underside of a tube is in the compression zone. I don't know of a typical head end impact that has a force acting on the frame which after compressing the fork rearwards then pulls it back out past the original point (remember springback). So my take is that if there's a ripple there's an angle change.

Now how much and how important (to the bike's handling0 is an angle change is a different story.

Lastly be careful how you measure a bike's geometry. It's easy to confuse center points, centerlines and whether the measurement is based on the two dimensional or the three dimensional. The below comment about wheelbase-chainstay=front center doesn't mention BB drop as an example. Andy.

gomango

Save your pennies and get a real Zullo.

I've owned four of these now and still have one.

Incredible riders. imho

Lookers too!

Here's one I found after a few minutes of searching.

NOS!



Here's the link to the frame. Little high on the price, but shoot him an email.

Make an offer. Shipping can't be that bad from Hamburg.

ww.ebay.it/itm/ZULLO-Rennrad-Rahmen-aus-Oria-KK-Stahl-54-cm-NEU-NOS-Stahlrahmen-/200820594993?pt=Sport_Radsport_Fahrradteile&hash=item2ec1d71931

BTW The frame you lost was nice for sentimental reasons, but it was only a Zullo fork anyway.

Frame was unidentified right?

Same seller had this one.

Certainly set my tail wagging!

Branimir

Sorry for bumping this topic back to life, but!

Local experienced repair guy/cycling champ straightened the frame, and since the fork was not repairable - he gave me a Colnago fork! Well not gave, but sold. Total repair+fork=53$



Wooohoo!

miamijim

I'm not sure how many frames you've straightened but I have a few 2-300 under my belt. Very simply the answer is yes, a ripple can still exist once a frame is straightened to its original angles.

The frameset I referenced to was within +/- 1/2 degree of the catalog spec without it being straightened. I'm sure that was within the original early 90's tolerance range.

fietsbob

Lugged frames do allow for frame builders to replace bent tubes
with straight new tubes.

Andrew R Stewart 

Of course there will still be a ripple remaining after rebending the frame. The area that distorted (the ripple) has work hardened. It will not bend as quickly as another area near by that hasn't been as cold worked. I never said that the ripple would need to go away for a frame repair. I was trying to say that the tube has changed it's length in a way that won't be restored by simple rebending. Aligning won't remove the missalignment, just add another to try to compensate for the first. Now the more skillful the repair person the less the extra stress that's added and the closer to a workable new geometry that results. I do agree that there is a workable range of head angle tolerance for a given fork geometry (to have a handling goal achieved).

One of my concerns with "lay people" doing this kind of repair is that they don't fully understand the factors involved and when "good enough" is achieved. Sometimes bending over and over again adding insult to injury. These same people often will neglect to monitor the frame/fork over the future. While steel is a wonderfully resilient material it will fail over time and if not looked for, the failure will happen when one doesn't expect it.

BYW I do know what I speak of. I've been doing this stuff since the mid 1970s. Learned from a number of very experienced guys along the way as well as my frame building work. I haven't bothered to count the repair jobs and have learned that more often then not they're not worth doing. But there are always the exception and these I consider. Andy.

Branimir

On the topic, the top tube does not show signs of a ripple, though on the downtube, there is an evidence of ripple, but on a different place than before. I don't know how exactly did the repair guy did it, but the geometry is now correct. Well, at least, I trust him, his experience and skills.