MintSauce Posted April 15, 2015 Posted April 15, 2015 Lengthening a fork steerer is not something that would be considered often, but seeing as the topic has come up from time to time in my 20odd years of riding, I thought I'd share this. About 18 months ago a friend offered me his old suspension fork at a really good price. The only snag was that the steerer was too short for my frame. I asked several experts and all agreed that there was nothing wrong with having the steerer tube lengthened by a reputable engineering shop. I subsequently had about 30mm added and built the bike up and forgot about it. This week I started stripping my bike to sell off the parts and found this... Needless to say I won't be doing that again!
NotSoBigBen Posted April 15, 2015 Posted April 15, 2015 Jeez dude, glad nothing happened while you were riding!
dirtrider Posted April 15, 2015 Posted April 15, 2015 Surely it's got an insert and will not just snap off !! Just a little crack in the welding .
gummibear Posted April 15, 2015 Posted April 15, 2015 Surely it's got an insert and will not just snap off !! Just a little crack in the welding .I would imagine that the star nut is about where the crack is.Won't be a good feeling holding the bars that aren't attached to the steerer Glad you found this before it was to late.
Sepia Posted April 15, 2015 Posted April 15, 2015 As Dirt said, Where is the welding? On the outside and then worn away? Was the joint butted?Have done this with no problems.
Steven Knoetze (sk27) Posted April 15, 2015 Posted April 15, 2015 Wowser, I bought a fork a while back without asking the correct questions. It ended up having a steerer that was too short for the frame. I also considered lengthening it and decided not to. I am glad I decided not to now.Scary thing is there are a lot of these fixes being done, it is accepted practice.
MintSauce Posted April 15, 2015 Author Posted April 15, 2015 The star nut was left in it's original position and the engineers turned a solid bar with about a 10mm shoulder that slid into the steerer. I then used an extra long bolt to secure the stem cap. The only thin preventing it from coming off is the zig-zag nature of the crack, as can be seen in the pic. With a bit of force, I'll probably be able to pull it off with my bare hands. Only thing keeping it on was the stem clamp force. I'm pretty sure had the join been below the stem, it would have snapped. Thankfully, that was one specific issue I considered before going ahead. If the join was below the stem I would definitely not have done it. I don't know if it's perhaps the fact a solid bar was joined to a tube that caused the break or perhaps using softer material than the steerer itself. I thought it might be softer material seeing as I've never seen a stem makes such deep marks on a steerer. Although, the marks could have been caused by the movement caused by the crack. No, I don't use a torque wrench, but I'm pretty confident it wasn't over-tightened.
MintSauce Posted April 15, 2015 Author Posted April 15, 2015 Welding was done on the outside and then ground/machined down
Skinnyone Posted April 15, 2015 Posted April 15, 2015 I have never advised to lengthen a steerer tube cuz a mate of mine did with a result that he lost teeth....
Sepia Posted April 15, 2015 Posted April 15, 2015 Welding was done on the outside and then ground/machined downThere Sir, lies the problem.
MintSauce Posted April 15, 2015 Author Posted April 15, 2015 Funny how you called them "experts". I am not any form of expert but I know that you really shouldn't try doing that sort of thing. Lucky it didn't fail while you were riding! There are a multitude of things in the world that are joined with welds that could threaten people's lives if they broke. If it wasn't safe, it wouldn't be considered an acceptable form of manufacturing. For some reason, this one failed. That doesn't mean it shouldn't be done. It means someone should/could identify what went wrong here so as to ensure it doesn't get repeated next time.
MintSauce Posted April 15, 2015 Author Posted April 15, 2015 There Sir, lies the problem. That's what I though as well. They probably didn't remove enough material from the 2 components to be able to 'fill' the joint with the weld and removed most of the weld when machining it down to size.
Shebeen Posted April 15, 2015 Posted April 15, 2015 whoopee, fork for sale? how long is the steerer?! i assume it hasn't been ridden much either!
GoLefty!! Posted April 15, 2015 Posted April 15, 2015 good catch Minty. I wouldn't lengthen it that way. Insert a new tube maybe yes but not weld in an extension. Its never going to be strong enough nor tough enough
BarryH Posted April 15, 2015 Posted April 15, 2015 heat treat the area around and on the weld and you will have a much better chance of success. it releases a lot of stress in the metal and reduce the risk of it cracking on the "surface" where the welded metal had changed its properties due to extreme heat.
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