Nessism

Anyone know where one can purchase an insert for a QS-10 fork (1.125" diameter steerer tube), or know of a work around? The steer tube is quite thin, so an expander plug seems risky.

Thanks.

Soil_Sampler

Yes, I have one.

You would have to find one that supports the entire length under the stem.

I would just use the Q-sert.

Nessism

Not following you exactly. You have an Alpha Q fork insert? You willing to sell it? You prefer a device known as a Q-sert instead of the Alpha Q insert? Googling "Q-sert" and coming up empty.

Shimagnolo

Lennard Zinn's tall forks were Alpha Q's before they stopped making them.
(He switched to Serotta after that.)
You might contact him to see if he has any inserts on hand, or knows of a substitute.

https://zinncycles.com/

FBinNY 

If you can't find an original liner, solve your problem with a bit of creativity.

The expander's only role is to provide enough traction to stay put against the pull of the top cap nut. It doesn't have to be rock tight and immovable, only tight enough not to slip. So consider buying a nice expander applying some adhesive to the outside, expanding it firmly to make a decent bond. Let cure, and you should be good to go.

Nessism

In the case of the Alpha Q forks, the steerer tube is really thin. About half as thick as a more conventional steerer. The inner sleeve piece is quite long and reinforces the steerer from the stem clamp loads. Honestly, after seeing this fork I'm questioning why I even bought it. Not a weight weenie in the least. Bike this is going on is a homebuilt lugged frame with a Look HSC3 fork currently installed. Got a fair bit of mileage on this bike (20k miles maybe) and the Look steerer is indented where the stem clamps. Thought it might be best to be safe instead of sorry and replace the fork.

Just measured the ID of the steerer and it's almost exactly 1". Going to look for a piece of aluminum tubing that fits snugly inside and go from there unless someone has a better suggestion.

FBinNY 

Check on steel electrical conduit at the hardware store. There might be a size that would serve effectively. The reality is that a steel liner will not ad much strength o rigidity to the structure because it's closer to the center (neutral axis) and the modulus of elasticity is too different for the steel liner and carbon tube to function as a single structure.

However if it extends well below the headset, a steel liner may act as a safety net staying intact if the carbon cracks.

Soil_Sampler

https://www.cornercycle.com/custom_ca...ork_insert.htm

q-sert is short 4 alpha q insert.

Soil_Sampler

https://www.universalcycles.com/shopp...1&category=100

Nessism

Thanks for the suggestions but still concerned about using an internal expander type insert on this Alpha Q steerer tube. Going to chase around to try to find the right part, or a reasonable facsimile. Found a nice piece of anodized aluminum tubing that's a decently snug fit inside the steerer. Going to cut a section of this unless I can find the right part. Oh, and emailed Zinn. Thanks for that suggestion.

Dave Mayer

I have an Alpha Q fork on my main road bike. The fork is a great design, is light and strong.
However, you should be concerned, as this fork has a very light steerer tube, and it MUST be reinforced with an appropriate insert. There are a few places on a bike where you do not take any chances, which includes the stem, bar and the fork. Failures here are often sudden and catastrophic.

The insert on this fork is not just to provide a place to root the expander, but it is required to reinforce the steerer against clamping forces by the stem. It is also required to resist bending forces in the vicinity of the headset . So the insert MUST EXTEND BELOW THE LEVEL OF THE TOP HEADSET BEARINGS. On my bike, this means a 4" long insert, which is what the stock unit is. The insert must be expoxied securely in place. This also means that once the insert is installed, the steerer CANNOT BE CUT. Which explains why these forks are constantly cluttering up Ebay and Craigslist. Buyer beware.


The last install I did on one of these forks, I used the reducing shim from a stem. This shim was provided to shim a 1" threaded stem for installation on a bike with a 1 1/8" steerer tube. The dimensions were perfect, as was the length. I of course applied the appropriate dilgence in lightly sanding and then epoxying the insert in place. Final advice: measure carefully. One chance at cutting the steerer.

Nessism

Great feedback Dave. Thanks so much for taking the time to share your thoughts.

The info about how the insert needs to extend below the headset is just the sort of info I'm looking for. The piece of aluminum tubing I found is plenty long enough so I'll keep this in mind. Searching the internet showed some photos of a broken Alpha Q steerer (and a bloodied guys face). The steerer broke just below the insert so I'm thinking it can't be too long.

Does the stock fork use a star washer inserted inside the insert tube, or is there some other method used to tighten down the stem stack?

Shimagnolo

I have two Alpha Q documents.
One is attached.
The other is installation instructions in PPT format which I cannot attach.
Send me a PM with your email address if you want it.

CACycling

By the time you factor in the weight of the insert and the epoxy, is there still a significant weight savings? Seems like a lot of downside for what seems like little, if any, reduction in weight. Or is there some other advantage?

FBinNY 

The advantage is some degree of immunity to user error in overtightening the expander and damaging the steerer (it does happen). There's alse a bit of a safety net effect in having a sleeve transition from the stem to deep below the upper HS bearing. If the carbon steerer should crack below the stem(which they've been known to do in rough service) the steel tube which is more ductile could hold together long enough to prevent a crash.

OTOH, this system might just be a clever idea Alpha-Q came up with to limit resale of used forks.

Dave Mayer

U R welcome. The fork does use a star washer which is installed in the normal way inside the insert. Since the insert effectively reduces the inside diameter of the steerer tube, I think you'll need a star nut for a 1" threadless fork. Please measure. I assume you could also install an expander wedge type setup made for 1" carbon forks. Both are getting harder to find, but Ebay should deliver.

The Alpha Q design was efficient, in that it placed material where it was needed. It also would have been somewhat more idiot proof, in that in the early days of full carbon forks, there were likely a lot of mechanics who were blissfully hammering star nuts into carbon steerer tubes. The use of an alu insert protected against that.

However, where the Alpha Q concept can go wrong is where the mechanic installs the insert, and then cuts to size. Or when a fork is resold.

Anyway, this fork should provide years of safe service and great ride quality if installed correctly. Your fork is worth installing - correctly.

unterhausen

now you guys have me paranoid about the fork I bought. The steerer is full-length, but the insert is installed. I was just going to cut the steerer down to size, but I don't know if I need to cut 4" off of the steerer. Might have to take part of the insert out on my lathe

Dave Mayer

I would only buy an Alpha Q fork under the following conditions:

1. It was NOS - fresh before installation
2. It was used, the exact size I needed, and I knew that the steerer never been cut, and that the full 4" of insert was securely in place. And that the mechanic who installed the insert was competent. I have seen one of these forks for sale with the seller saying that the insert had been removed. If this is the case, then the install had been a complete failure, and the carbon steerer then had been compromised from the stem clamping forces.
3. Or the insert is in place, and you start fresh by cutting the top 4" off of the fork. This is what happened for me, in that the original owner of my fork was around 6' 8" tall, and I was able to cut a bunch of steerer tube off.

Buyer beware.

Soil_Sampler

this Colnago expander looks long enough?

Nessism

Colnago expander looks GOOD! Thinking of going home brew though.

Found a nice piece of anodized aluminum tubing that's a perfect fit inside the steerer. Tube only goes in about 60% of the way to the crown, I assume because the fork was constructed with fibers attaching well up into the steerer.

Going to cut the steerer tube to length then figure out how long I can make the insert. Thinking about making it as long as possible. Have some good 3M DP460 Epoxy waiting for just such a project.

Thanks to everyone for helping walk me though this exercise. Good fun...