Idle musings on what makes a bike ride 'smooth'

[NHAero]

I have work I should be doing but oh well...

This past week the weather has been perfect and I've ridden all four of my drop bar road bikes. I put the 700C wheels on the Bingham for the first time since the Supersix Evo Hi-Mod showed up in December. My totally subjective butt-o-meter says that the Supersix is a smoother ride than the Bingham.

Here's what's the same between the two bikes:
- Running 700Cx25 tires with light butyl tubes (GP5000 on the Bingham, Panaracer Agilest on the Supersix)
- Same carbon railed Bontrager saddle
- Same R9100 shifters
- Same Eggbeater pedals
- Contact points set up the same

So I sit on the bike the same and my body touches the two bikes with the same hardware.

Here's what's different:
- The Bingham is a relatively lightweight titanium frame made for me, with flat mount disc, and a Whisky No. 9 Road+ disc fork, whereas the Supersix is a very light, stock carbon rim brake frameset with matching fork. The frame geo is similar in terms of ETT and angles, the Supersix has a 20mm shorter chainstay and commensurately shorter wheelbase.
- The Supersix has a 25.4mm carbon seatpost, with less showing than on the Bingham with a Thomson Masterpiece.
- The Bingham has an Uno 90mm -7 stem, the Supersix has an Uno 100mm +17 stem. Bars are alloy Zipp XPLR on the Bingham, and Specialized carbon on the Supersix.
- Wheels on the Bingham are BTLOS 24/24 bladed spokes on 35mm deep carbon rims (22mm inner width). Wheels on the Supersix are Farsport Feder 20/24 bladed spokes 25mm deep carbon rims (21mm inner width).

The Supersix is my first carbon road bike and I kinda expected a harsh ride but it's just the opposite. And I feel that the rear end is more plush than the Bingham, less shock through the saddle. Am I feeling something real, and if so, what is (are) the cause(s)?

[eddief]

so you can keep making money to buy more bikes so you can keep wondering. don't lose your job due to idle imaginings. if you can really tell the difference between the rear end of two bikes you're a better man than I.

[fa63]

Many will agree that particular iteration of the SuperSix is one of the nicest riding bikes. I had one myself and found the ride quality to be sublime. While there isn't a lot of give/flex in a traditional double-diamond frame, there are things engineers can do with carbon layup and taking advantage of its anisotropic characteristics to make frames that are not only stiffer but can potentially ride better than a titanium frame. That doesn't mean titanium is bad; every material has its pros and cons.

That said, the Thomson Masterpiece is probably one of the stiffest seatposts in the market. You might want to try a different seatpost on the Bingham and see how it feels. The alloy vs. carbon handlebar could also be contributing to the difference, as well as the fork. Same for the wheels. Can you swap wheels between the two bikes and see if your assessment changes at all?

[Elefantino]

I'm waiting for someone to ask how you can ride on 700x25s.

[eddief]

it's the handlebar bag.

[NHAero]

Originally Posted by eddief

it's the handlebar bag.

Actually, the Supersix has been sporting the identical handlebar bag for the last few months...

[thwart]

Since you mention the rear end specifically, the Thomson straight post vs a smaller diameter carbon post is likely playing a role.

Disc forks are stiffer than a similar fork designed for rim brakes. And at least IME carbon h’bars feel just a little ‘smoother’ than a similar aluminum bar. And 35 mm deep rims usually ride stiffer than a 25 mm rim.

Nice bikes either way.

[vespasianus]

Originally Posted by thwart

Since you mention the rear end specifically, the Thomson straight post vs a smaller diameter carbon post is likely playing a role.

Disc forks are stiffer than a similar fork designed for rim brakes. And at least IME carbon h’bars feel just a little ‘smoother’ than a similar aluminum bar. And 35 mm deep rims usually ride stiffer than a 25 mm rim.

Nice bikes either way.

I would go with this. Thompson posts are notorious for being stiff. And carbon does a great job of reducing road buzz and harsh feel.

[NHAero]

Originally Posted by vespasianus

I would go with this. Thompson posts are notorious for being stiff. And carbon does a great job of reducing road buzz and harsh feel.

Just ordered a 27.2 to 25.4 shim, that will be a low cost experiment to put the Supersix set-up on the Bingham.

[thwart]

Originally Posted by NHAero

Just ordered a 27.2 to 25.4 shim, that will be a low cost experiment to put the Supersix set-up on the Bingham.

Unfortunately, you still have the rim depth and tire difference as well as the bars, so won’t be able to compare oranges to oranges.

Speaking of cost-effective… of course you could mount 28’s on the Bingham to likely make the two feel more similar. I’m assuming the Cannondale, given its vintage, has some tire clearance issues that mandate the 25’s? Even with ‘very good pavement’ you’ll feel a difference. Apparently increasing tire size trumps all other measures to make a bike ride smoother.

[NHAero]

Originally Posted by thwart

Unfortunately, you still have the rim depth and tire difference as well as the bars, so won’t be able to compare oranges to oranges.

Speaking of cost-effective… of course you could mount 28’s on the Bingham to likely make the two feel more similar. I’m assuming the Cannondale, given its vintage, has some tire clearance issues that mandate the 25’s? Even with ‘very good pavement’ you’ll feel a difference. Apparently increasing tire size trumps all other measures to make a bike ride smoother.

The Bingham usually wears 650Bx38 GK slicks so, as you note, tire size and pressure trumps it all. The Supersix as a 2016 Hi-Mod got increased tire clearance and would fit 28s. At 140 pounds on good pavement the 25s, which measure out at 26mm on these rims at 70 psi, are fine.

[dmitrik4]

Originally Posted by vespasianus

I would go with this. Thompson posts are notorious for being stiff. And carbon does a great job of reducing road buzz and harsh feel.

Cosign; seatposts are huge. My Roubaix came with the weird-looking CG-R post and the rear is incredibly plush on 32s; small stuff is completely erased and even big bumps have the edges rounded off. My Gunnar on 30s was stiff on a basic no name aluminum post but transformed with a Canyon VCLS carbon post.

[jamesdak]

Best seatpost for smoothness by far!



If you can spin a smooth cadence then you will be hard pressed to find a smoother riding bike.

[slowpoke]

Going back to NHAero's original intent of removing variables: ideally you have the same wheelset and seatpost diameter and that's probably as close as one gets for an experimenet.

And ultimately as thwart mentioned on page 1, rim brake forks should be more compliant than disc forks because they don't need that additional bracing so far down.

[tellyho]

Originally Posted by Elefantino

I'm waiting for someone to ask how you can ride on 700x25s.

It's because NHAero is a small human. His 25s are your 32s.