Longer Chainstays

[Jeffrey Ritter]

So, I see various posts about longer chainstays, but have struggled to find anything that explains their value in terms of aerodynamics or power output.

Also, I don't see any available in the Accessories section of the website and was wondering if they are a Cruzbike option or purchased elsewhere.

Thanks in advance.

 

[dtseng]

The pitfalls of longer chain stays are: increase the weight of front end and steering inertia and therefore making the bike more difficult to control; longer chain increases power loss and therefore less power to sprint; since the seat of CB is fixed, the length of chain stay has an effect on BB height and therefore aerodynamics.

 

[PeteClark]

Aerodynamics - for a tall person, a short chainstay would result in your feet churning up air that would otherwise have passed below your seat relatively undisturbed. The long chainstay gets your feet up more in line with your torso and minimizes your frontal area.

Power output - a short chainstay results in a more "open" hip angle. A tall chainstay results in a more "closed" hip angle. Some contend the latter is a more powerful position, but it seems open to debate.

Steering intertia - I've seen the comments about a longer chainstay making the bike less stable, but would not think that is related to the weight of a few inches of aluminum tubing and a few links of chain relative to the rest of the front end.

 

[Rampa]

You can vary this some degree with crank-arm length as well. If you use longer cranks, you can have the bottom bracket that much closer to you, and therefor up higher. Shorter cranks require a longer boom to have the same reach, but also often work better for ergonomics and comfort.

 

[DavidCH]

For a person 5'10 with a long chainstay I am noticing tiredness in my quads. Now if I were to raise the seat up an inch and put the boom out by a centimetre that could be the winning ticket.


Not sure if performance is better with a larger chainstay. I will fine tune the bike for another week before deciding.

Certainly the boom config is more like what was used in the wind tunnel experiment. I.e. more horizontal

 

[RAGBRAI VI]

I have a 451 Quest. I ordered and installed the chainstay that would have come with 559 wheels. This did 2 things for me: 1) I have size 12 feet and was worried about my heel hitting the DD clickbox, this is no longer a problem, 2) I was able to raise the crank to almost level with the seat and I then reclined the seat as far as it would go. I wondered if the extra "reach" would result in more pedal steer or adversely affect the handling; it didn't. I also reversed the stem on the riser to bring the handlebars closer to me since I had reclined the seat more. Throw in a Ventisit pad and I'm a happy camper.

 

[Seth Cooper]

Aerodynamics - for a tall person, a short chainstay would result in your feet churning up air that would otherwise have passed below your seat relatively undisturbed. The long chainstay gets your feet up more in line with your torso and minimizes your frontal area.

Power output - a short chainstay results in a more "open" hip angle. A tall chainstay results in a more "closed" hip angle. Some contend the latter is a more powerful position, but it seems open to debate.

Steering intertia - I've seen the comments about a longer chainstay making the bike less stable, but would not think that is related to the weight of a few inches of aluminum tubing and a few links of chain relative to the rest of the front end.

Yeah not really the weight. As the feet are moved further away from the steer axis, their inertia increases and it takes more effort to steer. You can demonstrate this to yourself by lifting your feet off the pedals while you are moving and feeling how much easier it is to steer. With a longer chainstay, you won't really feel a difference in the feet-off-the-pedals steering feel/stability, but you will feel the difference with feet-on-the-pedals.