Saddle fore aft ? help !
#26
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Right, there is no scientific evidence for KOPS, nor is there scientific evidence for any other 'method'. So consideration of all is possible, equally.
If you don;t understand the relationship of femur length, KOPS and ultimately cycling, then it's worth the process of thinking about it.
K. Bontrager - great guy, added a lot to bike equipment ideas, especially mtb. very glad he's been doing that - but he's never been involved in any scientific study on bike position.
so, his comments are 'opinion', from possibly his observation and thoughts, but more than any other thoughts? debatable.
There have been attempts at scientifc studies for saddle position and fore-aft.
Here are just 2 examples:
https://ojs.ub.uni-konstanz.de/cpa/a...view/4430/4120 (this one actually downloads a PDF - best I can determine is it's not infectious or virus containing... But download at your risk)
https://www.sciencedirect.com/scienc...66337621000093
This 2nd one is mighty 'scientific' and bites a big mouthful, funny in many ways, and ultimately completely ignores fore-aft in it's summary ... meaning, they're didn;t want to wrassle that Bar... LOL!
If therez some Sigh-ENz evidence for 'balance', I'd like to see that. Same for 'Mid-rail'.
Tomato Coupe was nicely succinct - "Yes, KOP gives you a somewhat arbitrary starting point, but so does the balance method. Strict adherence to either as the ultimate arbiter of saddle position is misguided."
I cede to that plume of terse wisdom.
Ride on
Yuri
If you don;t understand the relationship of femur length, KOPS and ultimately cycling, then it's worth the process of thinking about it.
K. Bontrager - great guy, added a lot to bike equipment ideas, especially mtb. very glad he's been doing that - but he's never been involved in any scientific study on bike position.
so, his comments are 'opinion', from possibly his observation and thoughts, but more than any other thoughts? debatable.
There have been attempts at scientifc studies for saddle position and fore-aft.
Here are just 2 examples:
https://ojs.ub.uni-konstanz.de/cpa/a...view/4430/4120 (this one actually downloads a PDF - best I can determine is it's not infectious or virus containing... But download at your risk)
https://www.sciencedirect.com/scienc...66337621000093
This 2nd one is mighty 'scientific' and bites a big mouthful, funny in many ways, and ultimately completely ignores fore-aft in it's summary ... meaning, they're didn;t want to wrassle that Bar... LOL!
If therez some Sigh-ENz evidence for 'balance', I'd like to see that. Same for 'Mid-rail'.
Tomato Coupe was nicely succinct - "Yes, KOP gives you a somewhat arbitrary starting point, but so does the balance method. Strict adherence to either as the ultimate arbiter of saddle position is misguided."
I cede to that plume of terse wisdom.
Ride on
Yuri
#27
Banned.
I totally agree that there is NO definitive scientific consensus to support any specific method of nailing down your saddle fore-aft position to the nearest mm. The balance method is probably the best approach as it requires some conscious thought about how you are actually dynamically balanced over your bike when pedalling. Being a mechanical engineer and well studied in vehicle dynamics, I find this kind of thing quite interesting. KOPS to me is nothing more than pseudo science. The relationship between my femur length, a plumb line down through the pedal axis and my dynamic balance on the bike makes no sense whatsoever. At best it's a coincidental relationship.
The only thing going for KOPS is that modern frames have reach and stack proportions that favor KOPS instead of Balance method. Meaning riders would only need little to no other modifications to their bikes if they go with KOPS.
To do a proper Balance method on modern frames that favors KOPS, you may have to replace the stem with a shorter one. You don't just move the saddle aft, you may need to move the handlebar aft as well to compensate for the change in reach. This is meant to keep a good back posture and to open the hip angle as much as possible.
If you do those things, the only difference between Balance method and KOPS would be the rider's body angle against the ground. The shoulder and hip angles would be the same, even the frontal area for aerodynamic drag. Theoretically, you should make the same amount of power and cruise at the same speed. I found that to be true in practice but Balance method is better due to superior comfort. If anyone is making less power in Balance method than KOPS, it's likely they didn't change the stem length when it was needed and possibly problems with pedaling technique.
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What you may want to try are some uphill repeats: adjust the saddle 5 mm each time, keeping an eye on your speed/power/cadence. For me, adjusting the saddle fore/aft (or height) by 5 mm can literally double my speed or cut it in half going up a 12% grade! I'd use that as a determination for position well before using some formula.
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What you may want to try are some uphill repeats: adjust the saddle 5 mm each time, keeping an eye on your speed/power/cadence. For me, adjusting the saddle fore/aft (or height) by 5 mm can literally double my speed or cut it in half going up a 12% grade! I'd use that as a determination for position well before using some formula.
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What you may want to try are some uphill repeats: adjust the saddle 5 mm each time, keeping an eye on your speed/power/cadence. For me, adjusting the saddle fore/aft (or height) by 5 mm can literally double my speed or cut it in half going up a 12% grade! I'd use that as a determination for position well before using some formula.
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#31
Banned.
It's actually quadruple the power output!!
KE=1/2 MVsquared. Velocity is squared. If you double speed that means at least quadruple increase in power!!!! And that's ignoring other factors like aerodynamic drag, rolling resistance of tires, etc!!!!
KE=1/2 MVsquared. Velocity is squared. If you double speed that means at least quadruple increase in power!!!! And that's ignoring other factors like aerodynamic drag, rolling resistance of tires, etc!!!!
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Ummmmm ... no. Kinetic energy is not power. Velocity pretty much scales linearly with power on a steep slope.
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This might indicate that your fit isn't quite in the ballpark. For instance, say your fore/aft is off by 20mm. If you adjust it by 5 mm, you're still off by 15 mm, so there probably won't be much difference. Whereas, if you're off by only 5 - 10 mm, you should notice a difference. (This assumes saddle height or bar positioning isn't significantly off . . . one of those could be the reason, too.)
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This might indicate that your fit isn't quite in the ballpark. For instance, say your fore/aft is off by 20mm. If you adjust it by 5 mm, you're still off by 15 mm, so there probably won't be much difference. Whereas, if you're off by only 5 - 10 mm, you should notice a difference. (This assumes saddle height or bar positioning isn't significantly off . . . one of those could be the reason, too.)
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this might indicate that your fit isn't quite in the ballpark. For instance, say your fore/aft is off by 20mm. If you adjust it by 5 mm, you're still off by 15 mm, so there probably won't be much difference. Whereas, if you're off by only 5 - 10 mm, you should notice a difference. (this assumes saddle height or bar positioning isn't significantly off . . . One of those could be the reason, too.)
I've actually got a Wahoo Kickr Bike, so it's very easy to do a full sweep of saddle fore/aft position, which I've done several times. It also simulates gradients up to 20%. My own conclusion was that saddle fore-aft position is not super-critical. It's more about finding a well balanced riding position rather than variation in power output. If you are seeing literally 100% power variation between 5 mm positions, then maybe some of your leg muscles are missing?
Last edited by PeteHski; 03-21-22 at 09:54 AM.
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Too right. To double my speed on a 12% gradient means going from 250W up to 500W. Now if I could only get that sort of power gain from a 5 mm saddle setback change. Or any change whatsoever.
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#40
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lol
I've actually got a Wahoo Kickr Bike, so it's very easy to do a full sweep of saddle fore/aft position, which I've done several times. It also simulates gradients up to 20%. My own conclusion was that saddle fore-aft position is not super-critical. It's more about finding a well balanced riding position rather than variation in power output. If you are seeing literally 100% power variation between 5 mm positions, then maybe some of your leg muscles are missing?
I've actually got a Wahoo Kickr Bike, so it's very easy to do a full sweep of saddle fore/aft position, which I've done several times. It also simulates gradients up to 20%. My own conclusion was that saddle fore-aft position is not super-critical. It's more about finding a well balanced riding position rather than variation in power output. If you are seeing literally 100% power variation between 5 mm positions, then maybe some of your leg muscles are missing?
Ride On
Yuri
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I tried both KOPS and Balance at least two months each.
I end up being faster on balance method due to greatly improved comfort and possibly more aerodynamic position.
I had to reduce stem length on my bike though because my balance position is significantly behind KOPS position. The balance position made me feel overstretched so I went for a shorter stem.
I end up being faster on balance method due to greatly improved comfort and possibly more aerodynamic position.
I had to reduce stem length on my bike though because my balance position is significantly behind KOPS position. The balance position made me feel overstretched so I went for a shorter stem.
#43
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Similar experience here, though most of my riding over my past 2 years has been on trainer. After moving my saddle (a Selle AnAtomica with very soft stretched-out skin then a B17 Imperial, then a nearly unused Brooks Pro) back to where I can easily lift my hands, for example to turn the pages of a book, I found my hands migrating back over time, and no longer in contact with the hoods. I'm on the lookout for a vintage-looking compact bar to take teh place of the long reach randonneur bars I now have. I have not taken that step yet.
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Thanks! With my experience with other bikes, I expect the same. Right now my impediment is laziness!
#45
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I think I may have set up my bike many years ago using KOPS as a random starting position. Then I rode... a lot.
What I noticed was that whenever I pedaled above tempo was that I moved forward on the saddle. So I moved the saddle forward a little at a time until I longer slid forward for more power and was still comfortable all of the time.
I'm probably forward of an average fore-aft position, but it works for me.
What I noticed was that whenever I pedaled above tempo was that I moved forward on the saddle. So I moved the saddle forward a little at a time until I longer slid forward for more power and was still comfortable all of the time.
I'm probably forward of an average fore-aft position, but it works for me.
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This bike has a pretty long TT, probably longer than I should have, but it's a good ride, very supple and responsive. I already have a "7" shaped stem on it, 7 or 8 cm, so it would be hard to go much shorter. I think I need it to be about between 2 and 4 cm closer, so I should be able to accomplish that going from a V-O rando bar to a true compact, but we'll see. I may also convert the stem to a quill mast topped by a threadless stem. That has worked well on a different bike faced with a reach tuning task
But with 650b, relatively low trail, 747 standard tubing and the ability to host 38 mm and 42 mm tires, I still have a few variables to play with.
But with 650b, relatively low trail, 747 standard tubing and the ability to host 38 mm and 42 mm tires, I still have a few variables to play with.
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I think I may have set up my bike many years ago using KOPS as a random starting position. Then I rode... a lot.
What I noticed was that whenever I pedaled above tempo was that I moved forward on the saddle. So I moved the saddle forward a little at a time until I longer slid forward for more power and was still comfortable all of the time.
I'm probably forward of an average fore-aft position, but it works for me.
What I noticed was that whenever I pedaled above tempo was that I moved forward on the saddle. So I moved the saddle forward a little at a time until I longer slid forward for more power and was still comfortable all of the time.
I'm probably forward of an average fore-aft position, but it works for me.
If you mean cadence 'tempo' (used often in the quite older days of racing) or the more modern usage regarding 'tempo' as high effort, steady state riding - as "David Formolo riding tempo for Pojacar"; or 'Tempo training" - that being a hard effort, steady pace.
In any case, a hard, sustained effort, which is quite below 'sprint', but 75 to 90% of max effort (still aerobic) will often have riders sliding onto the nose of the saddle. One can see that often happening to riders in a TT ride.
Most often its a combination of keeping a high cadence as well as using a bigger gear - its more than just 'spinning'. It's what Eddy Meant by 'Spin a Big Gear'.
Conversely, when a rider requires to 'push' a gear, seated - the rider may slide backward a bit and press hard against the saddle back. The idea of saddle designs like the COncors was to facilitate more 'support for for that pushing, with the slightly higher turned saddle back. Some like that others don't.
Saddle fore-aft has a spectrum of what works. Not uncommon, I had a number of bikes, each with different setup. For Criterium racing, I had my crit bike set with my saddle 1.5 cm further forward than I would normally call my primary saddle position - because Crits often required a very frequent high level effort, with high 'tempo' coming thru and out of every corner. Not unusual to be on the saddle nose for 60% of the race time. So a 'forward' position was needed and worked well. Not so for a circuit/road race, where a more balanced position was more desirable.
If the more forward saddle position works for a rider - no reason not to use it, especially riders who commonly 'spin' higher cadences.
If one is like me, I spin, but also will 'push' if there's a short section which can be ridden with more power than cadence. 'Pushing' for me is usually a cadence below 70, spiinning higher cadence is usually well over 100. In any case, I prefer my saddle position to allow both. SO not 'forward' or 'back', but in my' middle' - right where it is now.
Is it KOPS? I wouldn't know, since I haven't really checked for that in 45-ish years. Is It the Balance Method? I guess so, since I feel 'balanced' even when I'm on the rivet, or against the back of the saddle.
The Point - how one initially starts to set saddle position is just a start point, not cast in stone. Rider riding, over time, usually gets one to where it ends up. open your softboiled egg from either end - the result is going to be the same.
Ride On
Yuri
#48
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I had some knee pain after riding so thought I would check my saddle fore and aft position. It was off by a couple cm based on KOPS. After setting it correctly the knee pain stopped.
There is no better place to start then using the KOPS method as a starting position for the initial fitting. In many cases it's all that's needed, Make adjustments from there as you see fit.
The balance method is a non starter for me since I don't have a trainer and will not ride on the street no hands.
There is no better place to start then using the KOPS method as a starting position for the initial fitting. In many cases it's all that's needed, Make adjustments from there as you see fit.
The balance method is a non starter for me since I don't have a trainer and will not ride on the street no hands.
Last edited by xroadcharlie; 03-27-22 at 06:12 AM.
#49
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We can also discuss what me mean by a "long ride", but for me, it means several hours. Definitely more than 3 and probably less than 8 including rest stops.
#50
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I want to have my butt centered on the widest part of the saddle and be able to comfortably reach the handlebars while having my back at a 45 degree angle. When riding, having warmed up for 10 minutes, I want the saddle to handlebar distance to feel right and by that I mean that I do not feel the need to slide further back or further forward to have support from the seat and be able to pedal effectively.
What is also important for me is the seat angle and usually I have it set at a 4 degree down angle from being perfectly horizontal but it varies by seat. I take a hex wrench and make adjustments as I ride a section with flats and hills.
So I adjust seat height first and then make a preliminary seat position of 24 inches from butt center to the top of the stem, and then I ride and adjust, ride and adjust until it is right for me. Doing this adjustment sitting still on a bike in a shop is not the best way to do this.
Race cars have their suspensions tuned in much the same manner where the driver takes it out on the race course and then based on what the driver reports the mechanics will make adjustment and this process is repeated again and again. And it is not done with the car up on a rack but with it out on the road.
What is also important for me is the seat angle and usually I have it set at a 4 degree down angle from being perfectly horizontal but it varies by seat. I take a hex wrench and make adjustments as I ride a section with flats and hills.
So I adjust seat height first and then make a preliminary seat position of 24 inches from butt center to the top of the stem, and then I ride and adjust, ride and adjust until it is right for me. Doing this adjustment sitting still on a bike in a shop is not the best way to do this.
Race cars have their suspensions tuned in much the same manner where the driver takes it out on the race course and then based on what the driver reports the mechanics will make adjustment and this process is repeated again and again. And it is not done with the car up on a rack but with it out on the road.
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