ryujin

stupid dog ran out in front of my bike and i had to serve to miss it

Ended up hitting a stupid steel park bench, heres a pic

https://img525.imageshack.us/i/img0134oh.jpg/

Most of it appears to be cosmetic, but to the left, a bit of the carbon has been damaged, although not very deep (the red is from the park bench).

Do you guys think i need to change the fork

And if so would this one be ok? (in terms of sizing etc.)

https://www.merlincycles.co.uk/Bike+S...LUMBUSTUSK.htm


I have a trek 1.2 compact 2010

Zef

This is not a recommendation to ride a structurally damaged fork but if you think that the gouges are just in the outer layer of carbon then you can sand the area smooth, including the paint around that general area of the fork and then lay on some new carbon fiber cloth and resin. There is a youtube video demonstrating repair of carbon fiber tubing/fishing poles that demonstrates wrapping the still wet area with some kind of heat shrink wrapping to help squeeze/form/and set the resin/carbon repair.

If you have any question whether the fork is structurally sound or not then you should not be asking questions about it...there is nothing anyone will be able to tell you definitively either way about your fork from pictures and you would need special equipment to conduct non-destructive testing to confirm if there is any underlying damage that may affect the structural integrity of the fork.

But...if you think it is just really bad cosmetic damage the patch will be ugly but is often much stronger than the unrepaired fork if done correctly due to the extra layer of carbon.

-j

ryujin

thanks, i think i am a little uncomfortable cycling on it, so gonna replace it, do you know whether the one i linked earlier would be suitable?

the only info i have on my fork is that they are "Fork: Bontrager Approved, Carbon" not sure of the size, if it help my bike frame is 56cm....

or maybe i should spend a little more and get these:

https://www.actionbikes.co.uk/bontrag...igid-fork.html

i think they are the same as the ones on my current bike... maybe?

HillRider

I agree with your decision to replace the fork. Without an expert apraisal, there is no way to tell if the damage is superficial or structural and it's not worth the risk.

Either fork you show should be satisfactory except the Columbus fork doesn't specify the steerer diameter (and it's out of stock) while the Bontrager specifies 1-1/8" (28.6 mm) which is what your frame requires.

FBinNY 

If it were the seat stay, or elsewhere on the bike, I'd probably patch and ride it. But not a fork blade.

I always base these decisions on a calculation involving likelihood of failure and possible consequences.

With carbon fiber it's hard to predict failure, and unlike steel which usually gives plenty of notice, carbon tends to fail catastrophically with no advance warning. So it's hard to estimate the likelihood, and I'd focus more on the potential consequences.

Fork blades have no redundancy, each being critical. If a fork blade fails the front wheel will cant against the other and probably lock up or at least make the bike difficult to control. There's a very high chance of taking a header. Since failure has a high probably of leading to serious injury, I don't tolerate much risk, and am extremely conservative about fork reliability.

As I said, the situation would be different if it were a seat stay. If one failed, there'd still be a chainstay providing wheel support, and if the wheel were to lock up, it would be a rear wheel lockup not a front likely causing road rash rather than serious bone or head injury.

It's just a fork, pony up the dough and replace it. Even if it isn't absolutely necessary, the peace of mind when descending a long hill will be worth it.

ryujin

hmmm well according to this ebay listing:

https://cgi.ebay.co.uk/Columbus-Tusk-...item4153826ec2

it is 1-1/8

and may just buy it from the ebay one seeing as the other one is out of stock!!

just making sure though, you're sure its suitable? cause trek 1.2 does have long drops for its brakes

HillRider

Neither fork specifies the required brake reach but i expect both require a "short reach" (37 - 47 mm) brake caliper.

Frankly, for someone who isn't certain what he needs, e-bay is a poor source for parts. Your LBS may charge a bit more but at least you will get the proper item the first time.

FBinNY 

Unless you know the seller or it's a listing from an established form, I'd pass on an ebay fork. You could go to the LBS, or if you feel that's too pricey, shop an established internet site, of which there are plenty enough to choose from.

Kimmo

I'd use a dial gauge and some weight to determine if the damaged leg was any weaker than the other one.

Chris_W

I've patched a carbon seat-stay that had worse damage, but I would never try doing so on a fork. As said above, the fork is too much of a safety risk. You need a new one.

jchabalk 

bad dog! go to your kennel

I'd replace it and feel good about doing it. Any injury prevented by replacing a critical piece of suspect gear is well worth the cost. +1 to FBinNY

HillRider

OK, and let's say the dial gauge says the fork blades are still the same. Would you ride the bike with that fork?

Looigi

Well, on a positive note, judging from the pics, your Crud fenders were unscathed.

ryujin

yea lol, they're completely unscathedwould have been annoyed if they were trashed, seeing as i only put them on last week!

fietsbob

Thy Trek dealer may help you, Perhaps they or Craig Calfee
[SF Cal carbon builder and repair guy]
will analyze, the damage, and if not de-laminated,
patch up the external appearance..

Or , say "replace" ..

RacerOne

Try your Trek dealer, if you bought it new you might get the crash replacement price.

ryujin

i didn't buy from new, but i went to my LBS, who have ordered me similar forks, cost me almost double what it would have online, but at least i know it'll be a good match!

thanks for your help guys!

HillRider

Good. Consider the extra cost as insurance that you will get a compatible fork that fits and works properly.