Is my LBS likely to be able to rethread my magnesium stem that stripped the thread on re-building at arrival for IM Brazil? I got away with it race day by using a slightly larger bolt, it was 1 of 4 as it is a Deda mag00 stem but there was a worrying amount of creaking when climbling out of the saddle! (Bunnyman)
What can I use to clean off my Renn disc as proprietary bike frame cleaner leaves smears and water leaves droplet runs? (Francois)
Will Tom D be stocking Kuota? (Why, this one is for Tom of course)
If your LBS has the correct tap they might be able to tap it to the next larger size bolt,a heli-coil would be the best way to fix the stripped thread if there is enough material (metal) around the hole thats there. I dought a LBS would have a heli-coil so you might have to go to a automotive machine shop,Sorry i am not on your list of experts,but just maybe i know what i am talking about
Helicoil would be best. Find an automotive machine shop to do this for you. If the bunnyman institute were to be a full-on customiser, ALL threads would be helicoiled on any soft metal, as this is the way that it’s done on soft aluminium parts in motorsport.
I would clean it (the Renn) with window spray, then polish with furniture polish.
Demmerly would be an idiot if he passes up the opportunity to stock Kuota. They have a nice range of product.
Thanks Tom, LBS is on to the stem now as I dropped it on Saturday and looks like they are going the slightly oversized route, but will be test riding it up the steep hill by the shop.
Can you respond to my pm when you know what availability is on a small Kailiber for me and then I could have my frame , fit and build from you at the same time with just the one air fare
Bunnyman, I didn’t like to ask Randall as he didn’t seem too pleased at being left off the experts list, can you explain what helicoil is? I know it’s out of my sphere of ability but am just a nosy sod who looks to add to his knowledge!
Throw the stem away. You have one of those "the stem"s, if I recall, right? Helicoiling, or rethreading to a larger size in a magnesium stem design that 1) has a history of failure and 2) is designed to push the limits of light weight is a risk not worth taking.
No, it’s a Mag00. It is a magnesium billeted stem, which is why I considered that it could be rethreaded. As I dropped around us$200 on it I would like to be able to use it althought I understand your comment. Serves me right!
OK - I haven’t heard anything bad about this stem, but you’re still nuts if you helicoil or re-tap oversize threads in a sub 100 gram stem. The fact that it is “billeted” doesn’t mean anything, and is in fact non-information; I can, off the top of my head, give about a dozen definitions of what constitutes a billetted stem, and most of them have nothing to do with each other. That’s irrelevent to the discussion, however.
A couple of years ago, I had a mound of test data on stems on my desk, and the hole size in the clamp area of the ultralight stems was pretty darn important - to get a stem that light, you push every tolerance to the limit, and when you modify the stem, well, you blow those tolerances right out the window. Scary.
To b honest, I have my doubts about using any of the truly ultralight stems in a tri-bar application. The lever arm of a tri bar is (probably) capable of producing significantly more force in the vertical plane than a set of road bars, and the clamp force of these stems is probably not adequate for this application at rated torque levels (note how many TT bars have slipped in the grand tour stages in the last couple of years.) I know that these stems are not being tested for this application, or at least they weren’t 13 months ago. Bad application for a very specialized product.
Let’s put it another way: Lance Armstrong was using Deda last year, and was able to use any of their products on his bikes. On his super lightweight climbing bike, where he used only one STI lever to save weight on the cable housing, he chose a Deda stem that was 2 full model lines heavier than the Mag stem. Armstrong is a total weight freak, but it just wasn’t worth the risk to go that light on a stem.
Helicoil= helical coil. All it is is a coil that gets into a hole and makes new threads. There are a few other trade names for them. I have never done one myself, personally, as I have always had this work done by a VW specialist machine shop. They are good enough to tell you whether or not it would be worth the time and trouble.
Fredly does bring up one good point about stems- a lightweight stem is not all that great for tri front ends. It can get into the stupid light stage if not careful. I am not a fan of carbon stems, either, as I don’t think carbon is a good application for a stem. I am also beginning to wonder if steel isn’t a better steer tube material for a tri or TT fork, if not the entire fork.
Maybe a helicoil ISN’T a good idea for the mag stem. I would have to see it, then defer to a machinist’s opinion as far as whether or not it would be a good thing to do.
A helicoil is a stainless piece of wire that is formed into what looks like a short spring,to install you have to drill the hole to a certain size depending on your insert,then using a special tap retap the hole,then screw the helicoil insert in,the insert now has the correct thread (inside thread) this will give you stronger threads and will be resistent to corrosion. The down side is having to remove material,with the new stems and as thin as they are you will be better suited to replace it,unless someone can look at it and think you have enough material to work with,also if this is the front clamp with only two boltsight not want to risk having a problem. And no i am not upset being left off your list of experts,just goes to show you no one looks at the profiles,and yes i have installed a few thousands
