einstruzende

As you can see, the steerer has been cut too short on my wife's bike. I can be blamed for this. I suspect I am going to have to buy a new fork, but perhaps there is an extender that is safe to use in this setup? Even 20mm would go a long way I think.

Failing that, does anyone know of a source of matte black forks that might be a suitable replacement? Doesn't necessarily have to be Colnago ...

(and yes the stem is upside down as an experiment. It didn't help and will be changed)

dedhed

You may be able to find a stem with a shorter "stack height" at the clamp.

icemilkcoffee 

FSA Metropolis stem. They make these in both 70mm and 90mm versions:

travbikeman

Just an idea, I have no experience on this so am not saying it works or not:

oldbobcat

There are special considerations for cutting and clamping carbon fiber steerers.

First the steerer is designed to be compressed from the outside, so the fibers are compressed inward, not outward. The expansion nut does compress outward, but since its only function is to stop the compression cap when you set the headset bearing load, the force it exerts is nominal. In fact, I have seen these nuts so overtightened that they deform the steerer making it impossible to slip spacers past. Also, the steerer is tapered, so, especially on a smaller frame like this one, the wedge of the quill extender is unlikely to find tube to compress against. But if it does, it will compress unevenly and destroy the steerer. So scratch that.

Remembering that the stem needs to compress the tube from the outside, note that compression needs to be firm enough to keep the bearing loaded and the handlebar straight. That requires precise machining, even pressure, and sufficient stack height where the stem compresses the steerer. That means a minimum stack height and at least two clamp bolts. When selecting a stem for a carbon steer, check the manufacturer's specifications for carbon compatibility. The better alloy stems by Zipp, Ritchey, FSA, Pro, etc. are recommended for carbon. That single-bolt riser stem will likely destroy the steerer.

Finally, the steerer is more delicate to damage by compression at the end where it is cut. You don't want to compress the top of the steerer with your top stem bolt unless the compression nut is directly and firmly behind it. Some compression plugs are made that way, but even then I really don't trust them, especially with unidirectional carbon. If somebody out there wants to argue with me, fine, but it's always safer to measure your cut to allow for a 5-10 mm headset spacer between the cap and the top of the stem. This also gives the rider wiggle room in case the stem needs to be raised a bit when working off the winter insulation, or what my neighbor calls the covid 19.

So it looks like you will be replacing the fork. Your local shop can get aftermarket carbon forks from QBP. This one has a tapered steerer so you'll have to read specs carefully if you go looking to other sources. Personally, I would get a replacement from Colnago and chalk it to an expensive lesson learned. And when you cut, use a guide, wrap the area to be cut with electrical tape to prevent splitting, and measure at least twice.

einstruzende

Thanks for the info, lots to consider. I don't mind paying for replacement, but I can't find a Colnago replacement fork. Not even on their website. So even though I'll "spend the money" there is no place to actually spend it!

oldbobcat

I found this list of Colnago dealers. https://www.colnago.com/en/dealers-list/ They obviously get their stock through an importer who has a district rep. Since district reps generally don't respond well to cold calls from end users, I suggest contacting the closest dealer, stating your problem (you need a fork), and asking them to contact their rep for you. Or give you the information for you to do it. I'm sure you're not the first guy who ever did this.

QBP has one fork model in stock, Whisky Parts No. 7, 1.25-1.5" tapered carbon steerer, 45 mm offset, crown clearance for 28 mm tires and short reach brake caliper with center bolt, matt black finish, MAP $325. Most local bike shops have QBP accounts.

Koyote

You should get an award for “most helpful bike forum member of the day.“

oldbobcat

Thanks, man. It's just that I've grown so accustomed to flames that I try to double check stuff before I post it. And then, I figure, I might as well post the links to the stuff I found.

veganbikes

In the future for anyone measure twice, then measure one more time for good luck and then cut after you have measured a couple more times.

Also keep in mind that FSA Metropolis stem may not be rated for carbon steerers and is out of production. It will also probably sit way too high so you probably won't get good engagement from the compression plug.

oldbobcat

Any part named "Metropolis" should never go on a Colnago anyway.

einstruzende

Thanks for the info, but what is this "QBP" that you speak of? I would happily pay $325 for a new fork!

70sSanO

You might want to check out a Columbus carbon fork. That would seem like an appropriate selection for a Colnago.

John

Juan el Boricua

https://www.qbp.com/

QBP or, Quality Bicycle Parts, is a bicycle parts specialist/distributor that serves most of the USoA bicycle shops (I'm unaware if it serves internationally; hopefuly someone more knowledgeable will chime in soon). They're wholesalers, so I do not think that they'll serve you individually, so maybe that's why he referred you to your local bike shop and have them place the order. Hope this helps and that you and your wife can roll together soon again.

oldbobcat

Quality Bike Parts, a very large general wholesaler of bike components and accessories. They have warehouses across the US, Canada, Mexico, and South America. You need to have a brick-and-mortar bike shop to get an account with these folks. They are very committed to the concept of neighborhood bike shops. (Also, their manufacturers make them.)

The other two I'm familiar with are United Bicycle Supply and J&B Importers. J&B is great for the stuff that keeps older, cheaper bikes alive.

veganbikes

It is actually Quality Bicycle Products

Yes they do serve internationally and your local bike shop can likely order from them. You as a normal person will not be able to do that unless you some how have an account but it is a good reason to stop by the local shop and maybe bring them the bike and have them do the work just so no issues.

PDKL45

Maybe use a different stem, like an Ergotec High Charisma or High Barracuda?

https://www.ergotec.de/en/products/vorbauten/sub/ahead-vorbau.html)

Camilo

edit: sorry, I didn't see 70sSanO post above. Regardless...

Check out the Columbus carbon fiber forks. They are very nice quality, good looking, all carbon, light weight, flat black, fairly low key logo-ing. Plus, they're Italian so wouldn't be a travesty on a Colnago! If they have one that suits you, I don't think the aesthetics would suffer too much. 8-)

Carbon Forks – Columbus (columbustubi.com)

I have a Minimal which is a great fork and I'm very happy with it. There's a bunch of varieties for various types of head tube and brake set ups. I'll bet you can fix your faux pas for in the reasonable vicinity $300US if you shop around. I bought mine from Chain Reaction for quite a bit less than that a couple of years ago. Then sell the Colnago to a tiny frame owner?

icemilkcoffee 

I have never heard of carbon steerer needing special stems. What makes you think the single bolt FSA stem would ‘destroy the steerer tube’ ?
If anything it’s probably better than the typical stem which have a hollow where the neck joins the trunk. In this FSA stem it’s all solid uniform mating surface.
Now it’s probably a good idea to chamfer the bottom ID of the stem(any stem) so there is no sharp edge digging into the carbon. Especially the corners created by the cut.
I chamfer the edges of the handlebar clamps that I use on my carbon handlebars.

oldbobcat

To prevent this kind of failure.


In this case the correct stem was installed incorrectly, too high in relation to the top of the steerer. Many manufacturers state in the user manual or warranty that using an improper stem or installing the stem incorrectly will void the frame warranty. Improper installation includes mounting the stem too high or even having too much steerer protruding from the top of the head tube. Headset spacers offer no reinforcement. Steerers are engineered for lightness and in some cases flexibility. They're not to be used like a seatpost. By the way, that's why seatposts and quill stems have minimum insertion lines.

DaveSSS 

I assume that there is about 40mm of steerer inside the stem. It's not difficult to fix this, as long as about 15mm of the original steerer is inside the stem, after it's extended. In other words, the steerer can be extended by up to 25mm, with a permanent thread insert for the top cap bolt. Any more extension would require an internal support tube.

I could fix it in 1 day and send it back the next. $35 should cover materials and return shipping.. Contact me if interested. I extended a steerer by about 10mm many years ago and rode that bike for years with no problem. I'm a mechanical engineer.

Here's a picture of an extension done to show how it works. The yellow tape line is the bottom of the stem. Inside the tube is a star nut with a reduced diameter, so it slides into the steerer. The star nut and all of the tube above it are encased in solid JB Weld epoxy, with a 6.5mm hole for the 6mm top cap bolt to go through. Ideally, about half of the stem height is the original tube and the top half is an extension. A copper tube coupling serves as the mold for the extension. I also use this technique, with no extension, to eliminate the need for an expanding plug.

70sSanO

Extend a carbon steering tube?

John