Dual crown fork install on 1.5 headtube

scrutton · Apr 18, 2016

Dual crown fork install on 1.5 headtube.

The frame (Trek Session 7) has a straight 1.5 headtube. Dual crown fork (Marzocchi 888) has a 1 1/8" steerer tube. Frame currently has a Bontrager Big Earl headset in it (for 1.5" steerer fork).

What do I need to make this work? Do I need to locate a 1.5-1-1/8 reducer headset, or can I buy reducer cups and use most of the existing headset.

Any suggestions on parts? FSA Orbit headsets/reducer cups still seem to be available.

Gemini2k05 · Apr 18, 2016

Just buy a cane creek reducing headset.

scrutton · Apr 19, 2016

Gemini2k05 said:
Just buy a cane creek reducing headset.

Sadly, those don't seem to be available anymore.

scrutton · Apr 19, 2016

After some searching, I think I've figured out how to do this :-
Either :-
1. buy a reducer headset
or
2. buy reducer cups, and buy a 1-1/8" headset.

kenbentit · Apr 19, 2016

Chris King Devolution headset. It just uses a different baseplate to adapt the 1.5 cup to a 1 1/8" steer tube.
https://www.chrisking.com/product/devo-baseplates/

IntenseMack10 · Apr 19, 2016

Another thing to be aware of is if your frame has a tall head tube, like many older DH bikes do, you can get the King Inset 4 to reduce the overall stack height. That's what I ran on 2 generations of V10 till this most recent one that has a shorter head tube.

Straight 1.5 head tubes on DH bikes are kinda nice for this versatility.

scrutton · Apr 19, 2016

IntenseMack10 said:
Another thing to be aware of is if your frame has a tall head tube, like many older DH bikes do, you can get the King Inset 4 to reduce the overall stack height.

I'm not sure I understand how this would work. From the CK website - "The Chris King InSet™ 4 is designed for 49mm headtubes and 1-1/8"steerer tubes commonly found on dual crown forks".

Now my steerer tube is 1.5" which I think would make it about 38.1mm (25.4mm in an inch, 25.4 x 1.5 = 38.1) Just guessing that, I can't really measure it as there is a fork installed in it at the moment). How would a 49mm Inset 4 headset fit in a 38.1mm diameter part of the steerer tube? I'm sure I'm missing something.

And, do you use the Inset 4 in place of the Devolution or in conjunction with some parts of it?

Joules · Apr 19, 2016

49mm is the ID of your head tube, which fits a 38mm steerer. You are trying to install a 28.6mm steerer in the 49mm head tube, this leaves enough room to put the bearings inside, which reduces overall height.

Inset or Devolution is either/or, not both. There are cheaper options also; Cane Creek ZS49 is less than a third the price of the king. An FSA orbit reducer runs $38 at Universal.

Gemini2k05 · Apr 20, 2016

scrutton said:
Sadly, those don't seem to be available anymore.

Just checked their website, definitely still availble to find a headset that lets a 1-1/8 fork fit in a 1.5 headtube frame.

Don't ever quesiton me again.

Flamingtaco · Apr 20, 2016

My solution was to keep the headset and use a piece of 1.125id x 1.50od aluminum tubing so I wouldn't have to replace the spacers and stem as well. 3ft was $20 shipped. Cost will be $5 once I sell off the rest.

scrutton · Apr 20, 2016

Gemini2k05 said:
Just checked their website, definitely still availble to find a headset that lets a 1-1/8 fork fit in a 1.5 headtube frame.

Don't ever quesiton me again.

Hope no offense was taken. I think I was confused with regard model names. Appears that the 40/110 series would work and these are still in production.

Carl Mega · Apr 20, 2016

I did this last season...ebay for $60 - Cane Creek 40 Series Conversion ZS49/28.6 ZS49/30

Dual crown fork install on 1.5 headtube

scrutton

Gemini2k05

scrutton

scrutton

kenbentit

IntenseMack10

scrutton

Joules

Gemini2k05

Flamingtaco

scrutton

Carl Mega

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