bdooner

Have bigger tire sizes and hydroforming revived aluminum? Or?

europa

My aluminium framed, carbon fibre forked bike with 28mm tyres is almost as comfortable as my steel framed bike with 23mm tyres. With 23mm tyres, the aluminium bike is noticeably less comfortable than the steel bike. Changing to 28mm tyres made a surprising difference to the aluminum bike.

Only a few years ago, skinny tyres weren't sexy and so manufacturers didn't use them. I think the only reason manufacturers are going to fatter tyres now is that they are the latest fashion ie, despite the difference in comfort, I don't think that's relevant, it's all about fashion.

Spoonrobot 

Maybe for the manufacturer's bottom line with respect to failed frame warranty replacements and wasted production due to manufacturing errors as well a the bicycle company's ability to market new features that don't change much for the end user.

The vast majority of hydroformed aluminum frames I've ridden have been extremely stiff, especially when designed as a endurance road or gravel bike. I don't think the industrial knowledge or maybe even physical constraints, are there to make a square/rectangle/triangle shaped tube as compliant as a round tube.

Lazyass

Tires aside, yes, hydroforming has made aluminum frames more complaint. What most people don't realize is that steel is stiffer than aluminum (just crush an aluminum can). The early alu frames were constructed like steel with small round tubes and they were noodles. Steel can be made with small round tubes because the material is stiffer and stronger. So in the late 80's they started making alu frames with huge round tubes. They made them less noodly but kind stiff riding. I personally don't think they're as bad as everyone makes them out to be. Hydroforming changed that because now they can be designed and shaped like carbon, stiff where you want it, such as in the HT and BB, and compliant where you want it.

Carbon also had a reputation for being flexy when they first came out with small round tubing.

Another factor is that in the 90's most of us were running 23's or even 20's at 120 freaking PSI. I personally ran 20's for about 8-10 years. Now that we're more knowledgeable in rolling resistance, ect, we know better. But that helped give alu the unfair reputation it has.

fietsbob

Hydro forming shapes the tube to meet the local stresses of that joint, and here aluminum works well at low cost..

Saw a picture of a Bridgestone, Japan steel frame they hydro formed.. the tubes .. expect it was not cheap to do..

deapee

I've had a couple cf bikes. I enjoy both of my aluminum bikes that I currently have. I run 24's on my road bike and actually have 24's on my cross/trainer bike also. But I do have two sets of 32's for the cross bike as well.

I don't really notice a difference in comfort to be honest, no matter what I'm riding or what size tires I have. They're all pretty comfortable.

Retro Grouch 

Good point!

I used to top up my (23 mm) tires to 120 psi every single ride. Today I'm using 1.5 inch tires. Every couple of weeks (or so) I top them up to 70 psi. Speed wise I'm roughly as competitive (or not) as I was with the bone shaker tires. I think that it's easy to over state the degree of difference that most of this detail stuff makes.