i bent my steel fork argh

[shaq-d]

hi guys,

well, got the pinarello treviso and spent a couple days sprucing it up (pix is in the gallery), with a new freewheel, cables, tires, etc. lo and behold i go out for a spin and at the tail end i end up in a low-speed crash into the car in front of me (we were on the left lane waiting to turn, and he accelerated then stopped for no reason whatsoever, so i couldn't stop in time). frame's alright, i'm alright, but front fork ended up bent so that the front wheel touches the downtube. i bent the fork forward 5mm so at least the wheel isn't touchign the downtube, with my hands and a lot of force; is there hope for the fork? ideas please..

:confused:

sd

edit: as you can see in the pic, the wheel is barely missing the downtube...

[Louis]

A few years ago a truck pulled out in front of me as I was flying down a hill on my steel Trek. I hit the brakes pretty hard but still T-boned him on the passenger’s door. My fork was bent much as yours and hit the downtube. (I also had some frame damage.)

A buddy of mine who had a long 2x4 with a fork mount bolted to it (designed specifically for this job!!!) helped me bend it back. The paint on the crown was wrinkled but I rode the fork for about two more years, until the rust on the crown got me worried about what might be happening. I had no special attachment to the Trek fork, so I replaced it with a Kestrel EMS. About a year after that the downtube cracked because of a wrinkle (due to the crash) just below the lower head tube lug. You may want to take a good look at the frame where the top tube and the down tube come out of the head tube lugs.

You might feel differently about your fork, so I’ll ask some of the Strength and Fatigue folks at work and see what they think. (I assume most of the strain went into the crown, since that’s what happened to me.) Basically, what you have is two big plastic deformations – the initial impact then the bending back. The question will be whether or not that’s enough to get a crack initiated now or at some time is the future. Some folks will be really conservative and say the only thing to do is to change the fork, but I’m sure others have bent forks back and ridden them for many years. I did the same, but then chickened out.

I’ll let you know what the experts at work say.

Louis

[coylifut]

Thank goodness your head-tube isn't a gonner. I can't imagine flying down a hill at 50 mph knowing what that fork once looked like. A crome steel fork isn't very rare. I'd surf ebay, maybe one will come along. Also, you could have one built for the price of a high quality carbon one.

[DfCas]

I bent a Waterfork cross fork in hard riding(no crash) and they said do not ride it.They reminded me that it was bent to align it when it was made,then I bent it,and to straighten it again was the third bend.

I replaced it with a carbon fork....

Dan C.

[shaq-d]

thanks for the thoughts guys; well, i called up a bike shop i never go to (it's a holiday here in toronto so just some are open) and ask them how much their cheapest road fork is, they say $60 (cdn!) which is cheap, so i thought, great, i'll go and see what they have. when i get there, they show me an ugly ugly fork, then we go to the back room's back room (the guy goes, "we call this the dungeon" lol), and voila, cdn$21 steel forks everywhere!!

so i'm just gonna replace the fork, and the good thing is their old steel fork is so old it looks similar to my pinarello fork... i'm still gonna bend back the pina fork in time though, cause i love that "P" logo they put at the top of the sides of the forks... louis let me know what the engineers say ;)

sd

[Ken Robb]

I'm sure you are going to make sure the fork's geometry is compatible with your bike, right?

[shaq-d]

i wish i KNEW what the old geometry before was, lol. anyone know what the rake on old pinarellos were? eye-ing it, though, the fork looked similar (lol, like i can eye a few mm's worth of difference).

sd

[Ken Robb]

I guess the prices for these old forks is ceap enough that you can afford to take a chance and try one for ride quality.

[Ken Robb]

another thought--go to Classic Rendezvous site for info and links to experts on old bikes who might just know the answer.

[JackL]

Looking at your photo, the fork now has little or no fork setback, which translates into a huge amount of trail. Also the shorter wheelbase changes the front center and puts more of your weight over the front wheel.

If the bike is safe to ride and doesn't have other problems, it would be interesting to ride it an note your observations. When the new fork is installed, ride again, and compare. handling.

[shaq-d]

ken, awesome site. i think i've got the info i need (73.5, 40mm rake seems to be the old pina geom)

sd

[Louis]

Shaq-d

I checked with some Strength engineers and as I suspected they said that they didn’t think it was a good idea, especially at a location that would be catastrophic failure. Not knowing how ductile the steel is makes it difficult to predict how the crown will behave after that plastic deformation.

If the fork isn’t that valuable to you and you can replace it easily, then by all means do so – less to worry about.

Louis

[Ozz]

I'd think you would want to get the frame checked out also...

It looks like you did a pretty good number on the fork, and damage to the frame may not be readily apparent. It would be tough to find out your frame was cracked on a 45+ mph descent!

At the least, get the alignment checked.

[Dekonick]

I know everyone is really sick of this formula - but

Kinetic energy = 1/2 (mass)(velocity)^2 - yup velocity SQUARED! - I wouldnt ride that bike until I had it checked really carefully. Think of it this way, your weight + Bike wt, at that speed = alot of energy. If you didnt get hurt, (and thank goodness you didnt!) that energy had to go somewhere.... obviously some went into the fork...but I'll bet some went to the frame too.

Sounds like it was a nice hill! :p

Bummer bout the bike tho. :crap:

[Keith A]

I would suggest you put a WTB ad in the rec.bicycles.marketplace newsgroup as well as the classified section on RoadBikeReview.com. You never know who might have an old fork lying around.

[shaq-d]

just thought i'd post what i did/results in the end. went to mike barry's bike specialties (which dbrk speaks so often so highly of), where they make mariposa steel frames, figured they'd know what to do with steel. at a bargain price of cdn$40, they fixed the steel fork and i'm back and running; no idea how they fixed it, but the ripples from the bending disappeared and it's as good as "new" (as new as a 20 yr old fork can be)... didn't get to chat with mike since he was busy, but they do good work...

sd

[Dekonick]

Mmmmmmmmmm - just make sure you wear a helmet descending on that fork the first few times... well - always wear one! :rolleyes: :crap:

Glad they were able to repair it! Did they have anyone help blow the bellows??? :D

[shaq-d]

grin, i always wear a helmet.. in fact i crashed mine earlier this year in a slow 4-10km/h fall, cracked the helmet and had a tiny headache, so i was glad. replaced it with a nicer one (even a slightly more expensive than cheap one at the local MEC/REI is great).

it feels sooooo good to have my red pina hanging from the ceiling again. i have no idea how they straightened out the fork..did they heat it up and let it cool again? well, rather not think about it ;) don't think i'll be taking it off-road though...

sd