Bent and straight forks
07-07-22, 09:18 AM
#51
Bike Butcher of Portland
Join Date: Jul 2014
Location: Portland, OR
Posts: 11,639
Bikes: It's complicated.
Mentioned: 1299 Post(s)
Tagged: 0 Thread(s)
Quoted: 4682 Post(s)
Liked 5,800 Times
in
2,284 Posts
Watch this fork flex. Imagine how much more it flexes when mostof the rider's weight is on it. Imagine 205lb Gugie vs 160lb Jan Heine.
From Rene Herse blog.
@JohnDThompson, do you have a link to Jan's straight vs curved fork testing? I could not find it.
From Rene Herse blog.
@JohnDThompson, do you have a link to Jan's straight vs curved fork testing? I could not find it.
__________________
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
Likes For gugie:
07-07-22, 11:09 AM
#52
Senior Member
Join Date: Feb 2008
Location: Peoria, IL
Posts: 4,476
Mentioned: 86 Post(s)
Tagged: 0 Thread(s)
Quoted: 1829 Post(s)
Liked 3,376 Times
in
1,580 Posts
The key results are on page 25....
edit: although this is just fork flex in general. Was there an article on straight vs curved? Might have to look again.
Steve in Peoria
07-07-22, 12:02 PM
#53
It's MY mountain
Join Date: Sep 2006
Location: Mt.Diablo
Posts: 10,002
Bikes: Klein, Merckx, Trek
Mentioned: 70 Post(s)
Tagged: 0 Thread(s)
Quoted: 4338 Post(s)
Liked 2,981 Times
in
1,617 Posts
Flexing absorbs energy.
But both forks take the same input/impact force. The curved fork absorbs some of the force and transfers the rest to the headset and into your arms.
The straight fork doesn't flex and transfers essentially all of the force into your headset and your arms.
Forks with elastomers or something have other means of absorbing some of the impact.
You could do an experiment where you measure the resultant force at the top of the head tube from a given input force on the fork dropouts to verify this.
I don't know if it's enough to make a difference in hand feel or headset life, but it exists.
07-07-22, 12:11 PM
#54
Bike Butcher of Portland
Join Date: Jul 2014
Location: Portland, OR
Posts: 11,639
Bikes: It's complicated.
Mentioned: 1299 Post(s)
Tagged: 0 Thread(s)
Quoted: 4682 Post(s)
Liked 5,800 Times
in
2,284 Posts
IIRC, it was Colnago's marketing department that promoted straight-blade forks in the late 80s to early-90s. I suspect it was done mostly to eliminate a manufacturing step (raking the fork blades) and thereby sightly reduce the cost of production, more than anything else. With carbon fiber forks, this isn't an issue, so the blade shape choice is simply cosmetic.
Jan Heine did a comparison of straight and curved fork blades and decided that curved blades offer slightly better shock absorption than straight blades, but were otherwise quite similar.
Jan Heine did a comparison of straight and curved fork blades and decided that curved blades offer slightly better shock absorption than straight blades, but were otherwise quite similar.
Right.
Flexing absorbs energy.
But both forks take the same input/impact force. The curved fork absorbs some of the force and transfers the rest to the headset and into your arms.
The straight fork doesn't flex and transfers essentially all of the force into your headset and your arms.
Forks with elastomers or something have other means of absorbing some of the impact.
You could do an experiment where you measure the resultant force at the top of the head tube from a given input force on the fork dropouts to verify this.
I don't know if it's enough to make a difference in hand feel or headset life, but it exists.
Flexing absorbs energy.
But both forks take the same input/impact force. The curved fork absorbs some of the force and transfers the rest to the headset and into your arms.
The straight fork doesn't flex and transfers essentially all of the force into your headset and your arms.
Forks with elastomers or something have other means of absorbing some of the impact.
You could do an experiment where you measure the resultant force at the top of the head tube from a given input force on the fork dropouts to verify this.
I don't know if it's enough to make a difference in hand feel or headset life, but it exists.
Flexing stores energy (it's a spring), less heat losses (essentially zero in this case)
Straight forks do flex. I don't have any straight bladed forks, if anybody wants to take a short video replicating the one from Rene Herse I posted above we'd have proof in a picture (video, actually)
From my ancient and half forgotten understanding of first princpals of mechanics of solids and materials that are used in forks, everything else being equal, a curved fork will flex the same as a straight fork. My spidey sense tells me this is a simplfiication, but it's "close enough" that most people wouldn't notice a difference.
__________________
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.
Last edited by gugie; 07-07-22 at 12:32 PM.
07-07-22, 12:26 PM
#55
Senior Member
Here's a test on Sheldon Brown's site
https://www.sheldonbrown.com/rinard/..._forktest.html
If I'm reading it right, the straight blade Colnago fork has the same deflection as the Merckx and Schwinn Paramount (Waterford).
https://www.sheldonbrown.com/rinard/..._forktest.html
If I'm reading it right, the straight blade Colnago fork has the same deflection as the Merckx and Schwinn Paramount (Waterford).
Likes For gearbasher:
07-07-22, 12:29 PM
#56
Senior Member
Join Date: Feb 2008
Location: Peoria, IL
Posts: 4,476
Mentioned: 86 Post(s)
Tagged: 0 Thread(s)
Quoted: 1829 Post(s)
Liked 3,376 Times
in
1,580 Posts
Looking through issue #23 again, the article on fork flex does show an illustration comparing straight to curved forks, but it's an argument that curved flexes more, but without any data.
Steve in Peoria
