You've probably noticed if you've been following these episcels that we're put 44mm head tubes on the new mountain bikes we're bringing out. This adaptation of the previous zero stack head tube standard was promoted by Sean at Vertigo Cycles in the US. If you like titanium artistry, go and check out his stuff.
Basically he wanted a sensible size and weight option for putting modern taper steerer forks into titanium frames because the massive zero stack and 1.5 standard head tubes developed already by mainstream aluminium builders look huge and ridiculous on smaller diameter ti (and by extension steel) tubes and weigh loads in materials like ti and steel. He suggested to Cane Creek that an external bottom cup on a 44mm internal diameter head tube (which already existed for zero stack headsets) would give enough clearance to the taper steerers using all existing tooling. The only new part required was the cup itself which bridges the 44mm head tube to the 1.5 bearing. Cane Creek took this on, and we steel and ti designers and builders got excited. It's really simple, elegant and results in a great way of futureproofing our frames without adding excess weight or massively outsized parts. For me personally, I still vividly remember avoiding buying a Bontrager Race Lite in 1996 because the US steel builders were doggedly hanging onto 1" headsets despite 1 1/8" having taken over throughout the rest of the industry. The last thing I wanted for steel bikes is a repeat of that episode with taper steerers.
With regard to the Solaris, Simple and Rocket it also offered another plus point over traditional 1 1/8" head tubes because it allows the use of zero stack top cups to keep the front ends low on the 29ers and long travel forks compatible Rocket. It also provides a perfect connection for the 40mm wide footprint of the Ovalform top tubes used on all these frames.
Our new frames have adopted the external bottom cup regardless of whether you're using a 1 1/8" steerer or taper. Whilst a regular zero stack bottom cup will fit if you're using 1 1/8" forks, it steepens all the angles by 0.5deg and more importantly for frame longevity, you will have no fork adjuster clearance to the down tube so using zero stack bottom cups has strong potential for damaged forks and frame as well as slightly shady handling. Hope have this completely covered with their new 2H headset. This has a crown race adaptor you can use for 1 1/8" forks leaving you free to upgrade to taper in the future without changing your headset. We'll be offering these with the new bikes for £75 for the headset including fitting, with the crown race adaptor an extra £10. Cane Creek, Nukeproof both do compatible headsets but none do the adaptor so you'll be commited to your steerer tube shape with those. The Chris King version has a 'Devolution' crown race option for running 1 1/8" steerers with their EC44 bearing bottom cup.