Bad day and a fork question

Clydesdale · #1 10-17-2017, 01:29 PM

Today's fixed ride - slow speed in an area doing work on streets. Pulled up to ease over a 3" ledge where new road meets old. Handlebars came off in hands. Not sure how I didn't hit the deck but managed to unclip and not crash.

Break is right at the headset with no vertical cracks above or below. Break is not at the stem as I had 2 spacers between stem and headset. I had noticed no loosening, play, noise, etc. I do not think I pulled up excessively hard, not even hard enough to wheelie, just to lift the front end to soften the bump.

I had a similar thing happen on a road bike a few years ago but that time I hit a pothole hard and it seemed more explainable. I have not crashed this bike or hit anything, but have ridden it hard and certainly have torqued the bars climbing, sprinting, etc.

I'm thinking I should stay away from carbon replacement?

veggieburger · #2 10-17-2017, 01:34 PM

Oh dang!!! Glad you're ok, that could have been a life-changer @ higher speeds.

eBAUMANN · #3 10-17-2017, 01:34 PM

sheesh, glad you walked away from that one!

how much steerer is actually in the stem? (i notice you dont have any spacers on top of the stem)

are you the original owner of the frame/fork?
its very possible that it was damaged previously in a more severe impact.

also...that fork is kinda "old," possibly past its "time."

Ken Robb · #4 10-17-2017, 01:46 PM

WOW! It's interesting that it didn't break near a clamped area. Is it possible that there was just enough play due to the top cap being slightly loose to allow sideways impact of the steerer into the head tube? That might have caused mini impacts that ate into the steerer over time?

berserk87 · #5 10-17-2017, 01:49 PM

I would say to avoid a carbon steerer tube in the future. If you are a Clyde, like your moniker implies, what benefit are you going to see in a carbon steerer versus an alloy one?

Two fork failures is bad karma.

ColonelJLloyd · #6 10-17-2017, 01:51 PM

echelon_john · #7 10-17-2017, 01:51 PM

Yikes! Glad you're ok. That could have been brutal.

If you go carbon replacement, I highly recommend the long inserts from Zinn; provide a little more strength through the whole stress zone. 12cm long!

http://www.bigandtallbike.com/Steer-...ter_p_380.html

eddief · #8 10-17-2017, 01:54 PM

Did you say what brand of fork?

Clean39T · #9 10-17-2017, 01:55 PM

Wow. If you do want a replacement, I have NOS high-end traditional forks with uncut steerers in the classifieds. Like eBaumann said, I'd question the clamping and suggest having the stem clamp the full tube with spacers on top. Or you could be unlucky.. Glad you are ok!

tuscanyswe · #10 10-17-2017, 02:06 PM

Is that an alpha q fork without the metal insert? If so that might explain your unfortunate event (or rather fortunate actually). Glad you are okay!!!

Edit: In case you dident know.
Those forks are suppose to have a glued in tubalar metal sheet that sits at the top of the steerer and a few inches down. The fork was designed with this in mind so the steerer material is not as thick as other carbon forks. If there is non in there, look no further as to the reason why.. One is suppose to glue it in yourself after you cut the fork to length.

Clydesdale · #11 10-17-2017, 02:27 PM

Quote:

Originally Posted by tuscanyswe

Is that an alpha q fork without the metal insert? If so that might explain your unfortunate event (or rather fortunate actually). Glad you are okay!!!

Fork is an Alpha Q with the insert but broke exactly at the bottom of the metal sleeve.

I don't think there was any play, but given the outcome I definitely could be wrong. Putting a spacer on top might be a wise idea.

For now I'm just going to stick with the theory that I'm strong enough to rip carbon forks apart!

David Tollefson · #12 10-17-2017, 02:58 PM

The headset has a split ring in the upper race, right? It applies axial pressure against the steerer, and it's fairly well known that it will cause deformation of the steerer over time. Add the lack of the insert in this area, and "voila", there ya go.

R3awak3n · #13 10-17-2017, 03:01 PM

I don't see the insert, the insert for the alpha q is usually pretty long.

Clydesdale · #14 10-17-2017, 03:06 PM

The insert is in the piece that came off with the stem. I would guess it is about 2 inches long, but I'll have to look again when I get home to be sure.

nicrump · #15 10-17-2017, 03:09 PM

Quote:

Originally Posted by Clydesdale

The insert is in the piece that came off with the stem. I would guess it is about 2 inches long, but I'll have to look again when I get home to be sure.

something is wrong. AQ inserts are about 5" long, bonded in and use an old style star nut. are you confusing a compression plug for an insert?