Why 1.5 inch head tubes on road bikes now?

[old_fat_and_slow]

Like most changes (cough, cough, "innovations") on road bikes, I am not understanding the current migration to 1.5 inch diameter head tubes. Hell, I never understood the need to change from 1 in to 1 1/8 in fork steerers.

I first noticed a few Ridley's showing up with tapered steerers, now I'm seeing bikes with full blown 1.5-in. diameter fork steerer tubes.

So what exactly is the benefit of a 1.5 inch steerer tube? Is this being driven primarily by the introduction of disc brakes on road bikes. Are bikes that are running disc brakes on 1 1/8 steerer tubes failing at the fork steerer? I don't have any road bikes with disc brakes so I don't have any first-hand experience. However, I still ride several frames with 1 inch forks and rim brakes, and I don't notice one iota of inadequate stiffness at the fork steerer on my bikes.

Is this just another case of the bike industry introducing a change just for marketing purposes to try to convince people to buy new bikes, or is there a legitimate reason for the change?

[oldpotatoe]

Like most changes (cough, cough, "innovations") on road bikes, I am not understanding the current migration to 1.5 inch diameter head tubes. Hell, I never understood the need to change from 1 in to 1 1/8 in fork steerers.

I first noticed a few Ridley's showing up with tapered steerers, now I'm seeing bikes with full blown 1.5-in. diameter fork steerer tubes.

So what exactly is the benefit of a 1.5 inch steerer tube? Is this being driven primarily by the introduction of disk brakes on road bikes. Are bikes that are running disk brakes on 1 1/8 steerer tubes failing at the fork steerer? I don't have any road bikes with disk brakes so I don't have any first-hand experience. However, I still ride several frames with 1 inch forks and rim brakes, and I don't notice one iota of inadequate stiffness at the fork steerer on my bikes.

Is this just another case of the bike industry introducing a change just for marketing purposes to try to convince people to buy new bikes, or is there a legitimate reason for the change?

I think it's primarily to save $(not passed on to the consumer, shocking, I know) because the 'manufacturers' see all their offerings become disc..and it probably DOES help with that considering how light the forks are getting.

[cmg]

The larger diameter head tube gives more area/more design options in terms of width for the top tube, down tube connection. That and it's easier to build a stiff less prone to failure fork. The wider width also makes it easier to accommodate the wider tires that have become favorable. I like the tapered fork look.

[FlashUNC]

The larger diameter head tube gives more area/more design options in terms of width for the top tube, down tube connection. That and it's easier to build a stiff less prone to failure fork. The wider width also makes it easier to accommodate the wider tires that have become favorable. I like the tapered fork look.

What he said. Let's not forget that for a bit anyways, 1.5" locks you into whatever proprietary stem/bar bits that Giant/Spec/Trek will want to sell you with the bike. So there's that added revenue stream too at some point if you need to positionally shift.

[Mark McM]

The larger diameter head tube gives more area/more design options in terms of width for the top tube, down tube connection. That and it's easier to build a stiff less prone to failure fork. The wider width also makes it easier to accommodate the wider tires that have become favorable. I like the tapered fork look.

Yes. The smaller 1" steerer diameter worked just fine with high strength density (strength per unit area) materials like steel, but larger diameters are more advantageous for low strength density materials like carbon fiber. Carbon fiber frames have larger diameter tubes for this reason, so it only makes sense that carbon forks also increase in diameter.

(Also, tapered carbon fiber steerers were introduced before disc brakes became common on road bikes. The stresses in the steerer are no different between disk and rim brakes, so there is no reason that a disc fork needs a stiffer/stronger steerer.)

[sfo1]

That

because the 'manufacturers' see all their offerings become disc.


and that


What he said. Let's not forget that for a bit anyways, 1.5" locks you into whatever proprietary stem/bar bits that Giant/Spec/Trek will want to sell you with the bike.


Personally, as someone that rides a bike with 200mm+ of HT, I like it.

[Hawker]

I really don't care for the clunky looks of the 1.5 inch head tube. Perhaps I'll get used to it....but I hope I don't have to.