I’ve ordered a carbon On-One Lurcher which has a “mixer taper head tube” (44mm upper, 49.6mm lower) and plan on using the forks from my old Giant which has Overdrive 2 steerer.
Is this a compatible combination? and do I have any alternative options to On-One’s Smoothie Mixer headset?

Isn’t Overdrive 2 Giant’s odd ‘standard’ with a 1¼” steerer?

Yep, hence my confusion.

Edit: it’s a 1.5 to 1.25 taper I think

Don’t think the Smoothie Mixer will work as the top one is presumably ZS44/28.6 and you need a ZS44/31.8. Only one I can find with the right top cup is the FSA No. 51 but the bottom cup is the wrong size.

http://www.pinkbike.com/news/Giant-OverDrive-2-Steerer-tube-sizing-2011.html

The impression I got reading articles like this, is that it should be compatible.
Anyone able to advise any further?

Giant’s overdrive system is horrid. With a 1.1/4″ steerer, won’t that limit your choice of stem to Giant only?

The impression I got reading articles like this, is that it should be compatible.

Yes and no. The bottom cup from the Smoothie Mixer should be compatible, but as I’ve said above, you’ll need a ZS44/31.8 top cup, and as per that PB article, the only people that seem to make those are FSA.

OverDrive2 is indeed a horrible ‘standard’; I notice that it’s not taken off in the two-three years PB were suggesting. Do new Giants still come with it?

You might want to have a look at the options Hope has put together – you can mix and match.
One other thing: What’s the offset on the Giant forks? You might want to understand what changes that makes to the geometry.

faustus – Member
Giant’s overdrive system is horrid. With a 1.1/4″ steerer, won’t that limit your choice of stem to Giant only?

Someone makes an overdrive stem, they had them on Wiggle

Yep – gone now though

http://www.wiggle.co.uk/chromag-ranger-125-overdrive-stem/

Giant’s overdrive system is horrid. With a 1.1/4″ steerer, won’t that limit your choice of stem to Giant only?

I heard that Ritchey do one, but of what is readily available it’s Giant only. I’m swapping the forks and stem from my old Anthem onto an On-One so stem etc isn’t a worry for me, just headset

Yes and no. The bottom cup from the Smoothie Mixer should be compatible, but as I’ve said above, you’ll need a ZS44/31.8 top cup, and as per that PB article, the only people that seem to make those are FSA.

OverDrive2 is indeed a horrible ‘standard’; I notice that it’s not taken off in the two-three years PB were suggesting. Do new Giants still come with it?
Hmmm that wasn’t what I wanted to hear!
It looks like it’s staying for the 2015 range.

You might want to have a look at the options Hope has put together – you can mix and match.
One other thing: What’s the offset on the Giant forks? You might want to understand what changes that makes to the geometry.

I had a quick look and from my limited understanding it doesn’t look like Hope have anything fit the top.
Not thought about the offset, is it likely to be different?

I think This might fit…

From what i read the top bearing is the same outer diameter but obv larger inner, so you should be able to get a generic Giant top cup and race?

Did a quick google and found this: http://www.mcconveycycles.com/store/product/18622/Giant-Fsa-Overdrive-2-Od2-Mtb-Headset/

Doesnt state the top bearing sizes but the part number leads to here:

http://www.thindustries.com.tw/?language=zh_TW&mod=7&class=1&mod_class=0&action=read&item=3

MR136 has an OD of 41.8mm and an OA of 45deg.

If the normal on one mixer headset has the same outer bearing dimensions then you should be able to use the bearing and split ring from the giant headset but obviously the top cap may be a problem as it may not fit the on one headset. Superstar and Hope also do headsets that will work in the On One frame.

If the Giant headset cup is the same OD (44mm) then it would fit.

edit: just looked up a Trance X on cane Creeks wesbite and it says the top is a 44 and the bottom a 56 which suggests the same zero stack top cup but a different (larger frame bore) zero stack 1.5″ bottom cup.

So you should be able to us an external 1.5″ lower cup ie an on one mixer, superstar tapered or Hope external along with a Giant OD2 top cup.

Awesome, thanks for the help.

Final question – will the bottom cup Hope Type F 49/40 1.5″ fit? (frame is a 49.6mm lower)
And if it will, I won’t need to order a separate crown race will I?

There’s a Hope Headset fitting chart; this suggests a Type F cup should fit.

What’s the offset on the Giant forks? You might want to understand what changes that makes to the geometry.

Offset shouldn’t make that much difference as he’s reusing the forks off an old bike which presumably have the appropriate offset for the wheel size. Anyway, how much difference does it really make (he says, using 46mm offset forks on a frame designed for 51mm)?

Anyway, how much difference does it really make (he says, using 46mm offset forks on a frame designed for 51mm)?

Apparently, quite a bit.
You might find your steering is a bit quicker. It won’t end the world, but I certainly noticed a difference.
Going on the rigid forks from my Singular Hummingbird back in the day, the offset has a significant (ie noticeable) difference in handling, especially when you’re moving between frames with different head tube angles and lengths, too.

Aside from the Hummingbird, Gary Fisher ran custom offsets on its G2 bikes – so it’s worth establishing whether Giant has, along with a non-standard steerer diammeter – also tinkered with offset.

Rather than edit that last comment: Probably worth looking at something written by someone who actually understands it properly (ie, not me) – here’s the Singular Cycles explanation: http://www.singularcycles.com/tech/

It looks like it’s staying for the 2015 range

Having had a look at Giant’s website (promoted by the comments on this post on BR) it looks like they have done away with OD2 – everything seems to be listed as OD, which is conventional 1.5-1? taper.