About this time last year, I began riding and wrenching bikes when I (over)paid $40 for a POS Puch Cavette ... it formerly belonged to a homeless man and nothing worked but I had a lot of fun learning with the bike as I got it in working order.

A few months later, I lent it to my friend and he returned it with the rear derailleur shoved so far into the spokes that all I could do was laugh. I am a poor college student so it spent a good amount of time as a single speed with the chain fixed to in reasonable gearing.

Eventually, I saved up some money and decided I want to be a hipster ******bag so I invested in a DT Swiss deep-v rim which I built around a Surly flip-flop hub and an aluminum IRD crankset... it was the best decision I have ever made. Frankenbike-ish as it may have been, the final product was my baby and it has left me with a soft spot for fixies build on vintage frames.



I bought the upgraded parts with the intention of investing in a nicer frame set some day... unfortunately, that day has come much sooner than intended. After lending my bike TO THE SAME FRIEND, he returned it like this...



He claims he was casually riding and it just happened... the chain was still intact but obvious it was off the cogs... the rear tree is so bend that the wheel was jammed against it. Luckily, somehow only the frame is damaged.

My questions are...
1) How the **** does this happen? I realize that a fixed gear has considerably more torque than this 12 speed frame was intended for but the above damage seems absurd.
2) What do I avoid in my next frame purchase? Is this just due to damage to the frame that went unnoticed... or are there some frames that should never be built into fixies?
3) I am certain that my Puch had BSC threading and I know that the bottom-bracket was square tapered because I bought those pricey squared tapered cranks to fit. What do I need to look for in a frame to make sure the cranks fit? Can it be Italian threaded? Or are there differences in the standards for bottom-brackets that limit me to a frame with BSC threading?
4) Anything else I am too ignorant to ask?

Basically... I would appreciate it if anyone could help me learn what I need to know while looking for a new frame. I have learned quite a bit about bikes but almost entirely from doing. I know "Google it" is a popular answer for easy questions on here but to be honest, I don't want to overlook some compatibility issue and wind up with expensive (for me) parts that can't be used.

Thanks! I apologize in advance for inevitably irritated half of you with this post.

Lesson one; NEVER EVER lend your bikes out, especially to that one.

Lesson two; Never cut any appendage off a old steel frame.


Sorry about your poor Puch, you former friend gave no explination? It looks like it was hit by a car or in a very serious accident. I bent a frame a bit like that once when the rear wheel slipped loose and locked up but I went bum over handlebars across the road so your former friend should be atleast a little bruised.

Are you interested in finding a road bike or a singlespeed/fixed gear bike? Either way but a quality ChroMoly frame. If you want a SS/FG buy a frame made for that. That way tou can use adjusters in the dropout to prevent the wheel from coming forward.

It's pretty unclear if he's lying... but he said he was just pedaling along pretty slowly and suddenly the rear wheel started skidding... he looked down and viola, the tree was in the state it is now. I have no doubt that under the right (or wrong) circumstances that the chain of a fix gear could fall off and get caught in the wrong way to do some damage... but not as casually as his story would indicate right? Typically I'm pretty good about checking the chain tension and making sure everything is in alignment... I live in NYC and ride rather aggressively so I figure the least I can do is know my bike is safe...

Anyways, irrelevant now, the Puch is dead and I need a new frame. As I said, I do kind of favor the style of classic road bikes from the 70-80s... I know there are more ideal frames for fixed gear builds like track frames but I've taken a few for a spin and nothing has been as nice of a ride as my brick ****house steel, steel-framed Puch.

Wow, I had chains snapping on me, wheels torqueing out of their mounts and a lot more stupid stuff beside, but never damage like this. I suspect either a crash with a car or a domestic accident with a heavy door or something..

So... any info on what I have to do to make sure I get a frame with a BB that works with my crankset?

Commonsense says that I can just buy a frame and install a square tapered bottom bracket... but my main question is whether or not there are any BB threading types that would make this impossible and therefore frames that should be avoided?

If you have a square taper crankset, it will screw on any taper, but it depends on spindle length and spindle standard (ISO or JIS) how far the crank will stick out, and by that it determines how your rear wheel should be spaced.

Read this:
https://sheldonbrown.com/chainline.html
and this:
https://sheldonbrown.com/bbtaper.html

Fixed gears don't put any more strain on the frame than a derailleur bike. There's no way that damage happened "just riding along."

4) Anything else I am too ignorant to ask?

A. Should he have volunteered to pay for the damages?
B. Should I drop him as a friend?


If you want to loan bikes to friends, have a backup bike!

Even if the breakage was completely by accident/bike failure at no fault of your friend, he should of still offered to help with expenses to fix/replace what he can. It's pretty selfish to borrow someone's property and bring it back broken. Definetly reconsider loaning him anything ever again, and I'd politely ask for some $$$ to offset your expenses.

Bicycle, motorcycle, knife, beer mug, torque wrench,camera, girl friend, car, and......

Don't lend anything out your not willing to loose....

Looking at the condition of the bike I'm just glad your friend did not loose his life...

You ought to thank your friend for saving you from having to take that fall.

When you were shelling out the bucks for the parts, did it occur to you that all that rust on the top tube and down tube might be cause for some concern?

Like you said...POS.

Just to clear things up, he is offering to pay for the cost of replacing a frame... up to $100 dollars to cover the inconvenience as well seeing as I unfortunately do not have all of the tools to make it happen very easily. He's a ****ty rider but a pretty decent friend.

Anyways, before I threw $300 worth of parts on the Puch frame, I checked the BB, seat tube, and head tube for rust and it was astoundingly clean on the inside. He later mentioned that he had taken a spill earlier in the week... I'm guessing he did something to misalign the drivetrain in the process... leading to catastrophic failure?

I didn't mean that fixed gears necessarily put more strain on the frame but if the chain were to slip off, there's a lot more direct force to be applied without the slack and added chain length in a derailluer system, right... essentially more torque I would imagine?

I can't see how the drivetrain can bend a frame like that, even if there were a lot of internal rust, leaving very thin frame tubes.

What size do you need? I have a 54 cm Trek 720 with bad paint. Email me.