Zinn Glue-in Carbon Fork Insert/Plug

[IFRider]

Folks,

Looking for any direct experience with using a Zinn Epoxy-in Steering Tube insert (https://www.bigandtallbike.com/Steer-Tube-insert-for-carbon-fork--238mm-Diameter_p_380.html). I came upon a Velonews article (https://www.velonews.com/gear/technical-faq-headset-spacer-stack-height/)researching Carbon fork spacer stack height. I am trying to get a handle on how much steerer can be above the headset and this looks to reinforce the steerer and allow more height and strength.

It seems to make sense, I am looking to use on an uncut Enve Cross Disk fork on an Ibis Hakka MX (stock fork).

Thanks,

Warren

[Velocipede]

Folks,

Looking for any direct experience with using a Zinn Epoxy-in Steering Tube insert (https://www.bigandtallbike.com/Steer-Tube-insert-for-carbon-fork--238mm-Diameter_p_380.html). I came upon a Velonews article (https://www.velonews.com/gear/technical-faq-headset-spacer-stack-height/)researching Carbon fork spacer stack height. I am trying to get a handle on how much steerer can be above the headset and this looks to reinforce the steerer and allow more height and strength.

It seems to make sense, I am looking to use on an uncut Enve Cross Disk fork on an Ibis Hakka MX (stock fork).

Thanks,

Warren

The fork manufacturer will list what you can have between the stem and headset. If it's Enve, that's 40mm. It's usually 30-40mm of spacer stack. And don't forget, they usually want a 5mm spacer above the stem under the preload cap. So it's really 35mm under the stem. Adding this type of insert, that doesn't mean you can add more spacers. This insert just makes a carbon fork safer.

[IFRider]

I appreciate the advice from a person in the business. That helps a ton, the insert is likely a path I will take to make the whole setup safer.

Warren

The fork manufacturer will list what you can have between the stem and headset. If it's Enve, that's 40mm. It's usually 30-40mm of spacer stack. And don't forget, they usually want a 5mm spacer above the stem under the preload cap. So it's really 35mm under the stem. Adding this type of insert, that doesn't mean you can add more spacers. This insert just makes a carbon fork safer.

[prototoast]

I don't know of anyone who has done any specific testing. 30-40mm of spacers is the norm from most fork manufacturers. If you wanted to go a little bit above that (e.g., 50-60mm), the Zinn insert is probably a good option. If you need to go way above that (e.g., 100mm under the stem), you probably ought to pay for a consult from Mr. Zinn directly.

[Velocipede]

I appreciate the advice from a person in the business. That helps a ton, the insert is likely a path I will take to make the whole setup safer.

Warren

Oh, it will make the set-up safer. That's the idea of it. I don't supply the smaller expanders. I can't stand them. They aren't safe. If you search the threads you will see one for the Bianchi rider who's fork sheered off. If he had one of these, it would've have.

[Velocipede]

I don't know of anyone who has done any specific testing. 30-40mm of spacers is the norm from most fork manufacturers. If you wanted to go a little bit above that (e.g., 50-60mm), the Zinn insert is probably a good option. If you need to go way above that (e.g., 100mm under the stem), you probably ought to pay for a consult from Mr. Zinn directly.

Zinn even mentions not going above the forks stated limit even with this in it.

If you want to do more, get an alloy steerer tube fork. Ritchey makes them. So does Fyxation.

[pbarry]

FWIW & Iirc, contemporary Wound Up forks have carbon wrapped alloy steer tubes.

[Velocipede]

FWIW & Iirc, contemporary Wound Up forks have carbon wrapped alloy steer tubes.

Not that I'm aware of. I know they do bonded carbon to alloy crowns. Always a trick looking fork. A bit underused and under appreciated honestly. But it doesn't always look right on certain bikes.

[osbk67]

I have fitted two of Zinn's aluminium inserts for carbon fibre steerers, both to Ritchey Carbon forks. Neither was to allow for a lot of spacers (one fork had 15mm of spacers between headset and stem, the other had no spacers) but to increase safety, especially for gravel and single track riding.

Very easy to fit following the instructions provided.

Prior to fitting the Zinn insert I had experienced problems with retention of headset adjustment on one of the bikes in question. In theory once the stem is tightened onto the carbon steerer tube the means of top cap retention is irrelevant, but I've had my doubts after seeing how steerer tube expander plugs bulge steerer tubes even at low torque settings. I'm optimistic the Zinn insert will improve things, as the steerer should remain constant in diameter when using one, but local lockdown rules haven't allowed enough riding to test this for sure...

I reckon they're a good simple product that improves an imperfect setup. Time will tell, as it always does.

[Jef58]

The original Alpha Q forks came with an insert and epoxy to bond in place. I have bonded supplied inserts like the ones from the Falz or Cinelli forks in place after the final cuts are made. The alpha one was pretty long, longer than the ones you buy now.

[Veloo]

This one is pretty long as well if extra length is all you are searching for:

https://www.chainreactioncycles.com/ca/en/colnago-fork-expander/rp-prod196617

Too bad they don't mention the length in the description.

[Velocipede]

This one is pretty long as well if extra length is all you are searching for:

https://www.chainreactioncycles.com/ca/en/colnago-fork-expander/rp-prod196617

Too bad they don't mention the length in the description.

The Colnago one is 85mm long.

[cmg]

The bottom of the glue-in tube needs to be below the top bearing of the headset. That is the greatest point of stress on the steering tube. The top of the stem upper bolt needs to be below the top of the glue-in tube. That's set the amount spacers that will be allowed. The stem thickness varies.

[cmg]

too many clicks.