Have I ruined my Tange Big Fork?

Titiritero

Retro Guru
I have a '92 Trek 950 with a nice Tange Big Fork. I did a long overdue overhaul last year and noticed the headset had "brinelling". According to Sheldon Brown, the solution was either to install a new headset, or cheap as I am, to replace the caged bearings for loose ones.

I'm just back from a 2 week offroad touring trip in Croatia, and the steering was "funny". Upon further inspection, it seems one of the loose bearings got in between frame and steerer tube, and has made its own channel into the steel.

Looking at the pictures I think I know the sad answer, but I'd like to get confirmation. Have I ruined the fork? Is it safe to continue riding as it is or better to replace immediately? Thanks to all!
 

Attachments

  • DSC03660.JPG
    DSC03660.JPG
    343.2 KB · Views: 810
  • DSC03661.JPG
    DSC03661.JPG
    132.6 KB · Views: 810
  • DSC03662.JPG
    DSC03662.JPG
    328.9 KB · Views: 810
  • DSC03663.JPG
    DSC03663.JPG
    318.2 KB · Views: 810

BentRims

Dirt Disciple
Re:

WOW!

I'd get another fork, looks to be a good size grove :shock:

Nothing worse than a Fork snapping off and kissing ground.

*edit* Is that groove on the front side of the forks? They gotta flex back too when you hit bumps and whatnot
 

Gruff

Retrobike Rider
Gold Trader
Kona Fan
Feedback
View
Re:

Ouch!
How long is the steerer? I have a Tange Big fork which you are welcome to for postage BUT it has a short steerer.
let me know by PM if interested.
 

Titiritero

Retro Guru
Re:

Gruff":36dlpm0m said:
How long is the steerer? I have a Tange Big fork which you are welcome to for postage BUT it has a short steerer.
let me know by PM if interested.

Wow, thanks! The headset tube in the frame is 12.5cm, I need to measure the steerer tube in the fork tonight but I'm guessing around 15cm to account for the headset stack.

Groove is on the back of the fork.
 

danson67

Retrobike Rider
Feedback
View
Personally, I would first file off the lip that has formed to get a good idea of how deep the groove actually is.

The wall thickness in that area is probably around 2.3 - 2.5mm, so I would worry if the groove was more than 0.5mm or 20%.
Luckily the groove is well rounded, so a lower stress raiser than a square or sharp notch.

IMO it's not as bad as it looks, but of course, the decision is yours.

All the best,
 

Titiritero

Retro Guru
Re:

I might be ok after all. I've done a bit of research based on danson's answer (thanks by the way!) and it seems he's correct.

According to this catalog scan (granted, it's from 1997 and my fork is from 1992), the Tange Big Fork steerer tube had 2.3mm at the bottom and 1.6mm at the top (thinner at the top to let the stem in)

http://www.equusbicycle.com/bike/tange/ ... at1997.pdf

I think my groove is at most 0.5mm, leaving me with at least 1.8mm thickness left, which should be ok, although still willing to be corrected!. I also use the bike for mtb (I'm trying to make it my do-it-all bike), but nothing too hardcore, and no jumps, I just don't have the skills. I do plenty of rocky paths though.
 

shedobits

Kona Fan
Feedback
View
Re: Fork woes

I have the same fork on my Singletrack and can't recommend them enough.
When you are riding the rocky trails would you be worrying about a potential failure or just enjoying the ride? Or I guess the real question should be " how are you going to pay the mortgage if that steerer tube failed"?
Seeing as these US built Treks are unfashionable at the moment they can be picked up for peanuts and you would get a free replacement headset too.
Alternatively, a second hand Project 2 in aheadset style with a matching headset would open up a whole new world of stems and bars giving that lovely frame a new lease of life.
Good luck with whatever you decide.
 

Titiritero

Retro Guru
Re:

shedobits":3w2t0av6 said:
When you are riding the rocky trails would you be worrying about a potential failure or just enjoying the ride?

I see your point. I'm being torn at the moment on what to do. On one side, I'll rather keep the original fork (even though I don't pretend to keep the bike original as I've been replacing with modern parts whatever wears out). On the other hand, the headset obviously needs replacement, and the stem is quite rusted and wouldn't hurt to get a higher one to raise the handlebar and give my back a break.

So going for a new fork and then change everything to ahead is not a bad solution either. I have another Trek 950 from '91, and that one is fully original, even the tires, so it's not like I won't have my garage queen. The only difference is that this one was bought used, while the other one is my first mtb, bought new in a shop when I was 16 so of course the value is different even if they are similar bikes.

I've already found a new rigid fork for 45 EUR, long steerer tube for a nice upright position, eyelets for a front rack (which I'd like to mount as I tour often and now I need to carry the luggage of my kids) and option for cantilever or disk if I ever switch to the dark side. And it's shiny black, like my frame. Mmmm, decisions...
 

Oldskool13

Old School Hero
Re:

Sorry to hijack your post but this has thrown me into a bit of a panic. I found similar damage where the top bearings sit on the forks of my Gumtree bargain bike. There was a groove and threads were pretty messed up on the left side of the steerer. It looks like the previous owner was going to fit a new headset, found the damage, threw it back together and left it in the shed for six or seven years until muggins turned up and bought it. No wonder he let me knock him down on the price!

I did a bit of a bodge fix by using a round file to remove the lip and cleaned up and removed the burrs on the damaged thread. Luckily the top of the threads was undamaged and there was enough left for the nuts on the new headset to tighten. I kind of reasoned because the damage is at the top, the handlebar stem would add strength.

I'm now wondering if I should replace the forks or not. The bike is basically going to be a pub/towpath cruiser so it won't be used in anger as such but I will be taking it out into the New Forest at some point. I found some new 26" rigid 1" threaded forks on Decathlon for £20.

Any thoughts?
 

shedobits

Kona Fan
Feedback
View
Re:

It will probably be OK being at the top of the steerer tube but 20 quid for a new fork seems a lot less than a dentist` bill. IMHO.
 
Top