How should wheels affect steering?

[SteveV0983]

Just got a new Vamoots with the Moots fork (which I believe is made by Enve) and new Ultegra WH-6700 wheels. Before the purchase, I had the Moots demo (same size) for a week and it had an Alpha Q fork and my old Mavic Open Pro/Ultegra wheels on it. The new bike with the Moots fork and Ultegra wheels has a much faster/more responsive steering than the demo had. It's not uncomfortable, but it is definitely different than the demo was. Both forks had a 40 rake, I used the exact same stem, same bars, same shifters, same tires, so it seems as though it is a truly fair comparison to say that the only change are the fork and the wheels. And seeing that both forks were carbon with the same rake, I think they should be similar. I have come up with 3 possibilities (in order of what I think is most likely):
1) Could the wheels be making it faster steering? The Ultegras are 16 spoke front, the Open Pros were 32.
2) Could it be that the Moots/Enve fork is "faster" steering than the Alpha Q was?
3) The demo steerer was cut so that I could only use 20 mm spacers, which put the bars lower than I like. But between an extended head tube and more spacers on my bike, I got the bars higher (which is where I prefer them) by about 30mm relative to the demo. So I am definitely higher up in the front.

Any thoughts on which it may be?

[Louis]

Both forks had a 40 rake

I'm no expert, but lot lots of things not directly related to the fork can affect handling.

But back to your train of thought, head tube angle does affect trail, so having the same rake does not necessarily mean that the two bikes had the same trail.

Enjoy the new bike. :bike:

[Kontact]

I think lighter or more aerodynamic wheels could easily make steering feel different.

Sitting up higher with a different weight distribution can definitely make steering feel twitchier. I just can't say how much a wheel and 1cm of extra spacers would change things.

If you want to be scientific, take a spacer out and put the other wheels in.

[monkeybanana86]

this is interesting. i would think if there was a big weight difference then for sure that would affect handling. like when i have my dynamo hub on for instance.
also when i ran a super heavy adjustable-reach-quill stem (more for novelty) on my track bike then went back to a regular stem it was like throwing a basketball after having thrown a medicine ball around for a while and the bike would go back to feeling way more responsive.

i don't have experience with small weight changes in the front that stick out but i'd be curious to see if indeed when you swapped the parts, like Kontact suggested, that it would make a difference. please let us know!

[Fivethumbs]

The Alpha Q forks had one of the longest axle to crown measurements. I think the Enve forks are shorter. Therefore, I am guessing the shorter fork lowered the front end and increased the head tube angle.

[palincss]

this is interesting. i would think if there was a big weight difference then for sure that would affect handling. like when i have my dynamo hub on for instance.


And you find a big handling difference when you use the dynamo hub vs an ordinary hub? I've swapped between dynamo and regular hubs on several of my bikes many times and have never felt any such thing. In fact, I have not even been able to detect the weight difference.

[soulspinner]

The Alpha Q forks had one of the longest axle to crown measurements. I think the Enve forks are shorter. Therefore, I am guessing the shorter fork lowered the front end and increased the head tube angle.

Good thought......

[oldpotatoe]

Just got a new Vamoots with the Moots fork (which I believe is made by Enve) and new Ultegra WH-6700 wheels. Before the purchase, I had the Moots demo (same size) for a week and it had an Alpha Q fork and my old Mavic Open Pro/Ultegra wheels on it. The new bike with the Moots fork and Ultegra wheels has a much faster/more responsive steering than the demo had. It's not uncomfortable, but it is definitely different than the demo was. Both forks had a 40 rake, I used the exact same stem, same bars, same shifters, same tires, so it seems as though it is a truly fair comparison to say that the only change are the fork and the wheels. And seeing that both forks were carbon with the same rake, I think they should be similar. I have come up with 3 possibilities (in order of what I think is most likely):
1) Could the wheels be making it faster steering? The Ultegras are 16 spoke front, the Open Pros were 32.
2) Could it be that the Moots/Enve fork is "faster" steering than the Alpha Q was?
3) The demo steerer was cut so that I could only use 20 mm spacers, which put the bars lower than I like. But between an extended head tube and more spacers on my bike, I got the bars higher (which is where I prefer them) by about 30mm relative to the demo. So I am definitely higher up in the front.

Any thoughts on which it may be?

For info-altho the Moots fork may be made in the same place as the ENVE, Moots for is not 'made by Enve'.

I think the stiffness, responsiveness of the fork may play a big part. Altho pretty light, the Moots fork is pretty burley.

[Grant McLean]

3) The demo steerer was cut so that I could only use 20 mm spacers, which put the bars lower than I like. But between an extended head tube and more spacers on my bike, I got the bars higher (which is where I prefer them) by about 30mm relative to the demo. So I am definitely higher up in the front.

Any thoughts on which it may be?

Higher bars is going to significantly change the weight distribution, and the
way the bike handles.

-g

[charliedid]

Higher bars is going to significantly change the weight distribution, and the
way the bike handles.

-g

Yep

I'm guessing you don't have the old wheels?

[SteveV0983]

Thanks for all the responses. I plan on switching out the front wheel to the Open Pro on my next ride to see if it is the wheel. Seems like this will definitely rule the wheel in or out. A couple of responses:

Louis, head tube angle was identical between the demo and my bike. Both are spec'd at 72.8, but being hand made, I guess they could have been slightly different. But they are pretty well know for tight tolerances.

Fivethumbs, this is really interesting. From what I've found online, the Alpha Q was 374 axle to crown and mine seems to measure 372, but I'm going to e-mail Moots and try to get the exact figure. I noticed that the Enve forks (which seem to be very popular on Moots bikes) are 367. They seem pretty adamant that they designed the fork to how they wanted the overall bike to handle, but this is a very interesting thought.

Kontact, I'm now actually 3cm higher in the front. They made the head tube with 1 cm additional length and I added 2 cm additional of spacers. So I am almost 1 1/4" higher in the front.

monkeybanana86, I believe the Ultegra front is 695g. According to Colorado Cyclist, an Open Pro with an Ultegra 6700 hub is 878g (mine may be slightly heavier with older 6600 hubs). Not sure if 183 g is significant enough or not, but it seems like quite a bit percentage-wise.

charliedid, I do in fact have the old wheels and plan on trying that today.

Thanks for all the great responses. Feel free to keep them coming.

Steve

[charliedid]

Thanks for all the responses. I plan on switching out the front wheel to the Open Pro on my next ride to see if it is the wheel. Seems like this will definitely rule the wheel in or out. A couple of responses:

Louis, head tube angle was identical between the demo and my bike. Both are spec'd at 72.8, but being hand made, I guess they could have been slightly different. But they are pretty well know for tight tolerances.

Fivethumbs, this is really interesting. From what I've found online, the Alpha Q was 374 axle to crown and mine seems to measure 372, but I'm going to e-mail Moots and try to get the exact figure. I noticed that the Enve forks (which seem to be very popular on Moots bikes) are 367. They seem pretty adamant that they designed the fork to how they wanted the overall bike to handle, but this is a very interesting thought.

Kontact, I'm now actually 3cm higher in the front. They made the head tube with 1 cm additional length and I added 2 cm additional of spacers. So I am almost 1 1/4" higher in the front.

monkeybanana86, I believe the Ultegra front is 695g. According to Colorado Cyclist, an Open Pro with an Ultegra 6700 hub is 878g (mine may be slightly heavier with older 6600 hubs). Not sure if 183 g is significant enough or not, but it seems like quite a bit percentage-wise.

charliedid, I do in fact have the old wheels and plan on trying that today.

Thanks for all the great responses. Feel free to keep them coming.

Steve

Good luck Steve and tell us how it goes...

[monkeybanana86]

And you find a big handling difference when you use the dynamo hub vs an ordinary hub? I've swapped between dynamo and regular hubs on several of my bikes many times and have never felt any such thing. In fact, I have not even been able to detect the weight difference.

If you can't detect a weight difference then you must have a light hub. Good for you. Mine indeed is old and heavy.

[palincss]

Higher bars is going to significantly change the weight distribution, and the
way the bike handles.


I having trouble believing it. You raise the bars let's say by 2 cm. That's a pretty big raise as far as handlebars are concerned. Does your weight distribution change as much as it does when you move from the hoods or the bar tops to the drops? No way. And yet, who notices a significant change in handling when you go from the hoods to the drops?

[tannhauser]

I think the stiffness, responsiveness of the fork may play a big part. Altho pretty light, the Moots fork is pretty burley.

This one.

[Kontact]

I having trouble believing it. You raise the bars let's say by 2 cm. That's a pretty big raise as far as handlebars are concerned. Does your weight distribution change as much as it does when you move from the hoods or the bar tops to the drops? No way. And yet, who notices a significant change in handling when you go from the hoods to the drops?
Apples and oranges. We expect the bike to feel different from hoods to drops, but we don't think about it because the two positions are so different. But move the same position enough and the contrast is more obvious.


Generally:
I kinda doubt the fork stiffness or axle to crown distance are going to be as significant as position or wheel dynamics. Hard cornering, maybe, but not on normal stuff.


What makes anyone think that the Moots for is an Enve? They aren't shaped the same.

[Jawn P]

I having trouble believing it. You raise the bars let's say by 2 cm. That's a pretty big raise as far as handlebars are concerned. Does your weight distribution change as much as it does when you move from the hoods or the bar tops to the drops? No way. And yet, who notices a significant change in handling when you go from the hoods to the drops?

Take a turn in the hoods, and then take the turn again in the drops. Feels pretty different to me.

[TPetsch]

The head tube angle should be checked against the Demo you rode for comparison. And as mentioned before the Axel to crown measurement may be several mm different between the Moots fork and the Alpha Q. Combined, these two slight differences could result in the quicker steering your experiencing.

[Grant McLean]

Does your weight distribution change as much as it does when you move from the hoods or the bar tops to the drops? No way. And yet, who notices a significant change in handling when you go from the hoods to the drops?

Yes, there is a huge difference in handling between the hoods and drops, and also there is to the tops.

-g

[SteveV0983]

Well, just got back from my ride and think I found it. First, I did the entire ride exactly as the bike had been set up (no changes) so my body would be freshly accustomed to it. Got home, swapped out the front wheel, and on just a short ride up and down my street it was noticeably different and much more stable. I'm going to do my next ride entirely on the Open Pro front wheel to confirm it, but it looks like this was the difference.

So let's say this is the difference and I prefer the ride of the Open Pro. What do you all think it is about the 2 different wheels that causes such a huge difference in handling? Weight? Lower spoke count? Stiffness?
In general, which of these 3 is more likely to make those Ultegras so "twitchy". They actually handle really well and are real comfortable, but I just need to decide if they are the ride I want on this bike. Some people may find the Ultegras nice and quick and the Open Pros kind of sluggish by comparison, so I know it's all subjective. But I'm curious which factors you think would have the biggest impact.

[Kontact]

Well, just got back from my ride and think I found it. First, I did the entire ride exactly as the bike had been set up (no changes) so my body would be freshly accustomed to it. Got home, swapped out the front wheel, and on just a short ride up and down my street it was noticeably different and much more stable. I'm going to do my next ride entirely on the Open Pro front wheel to confirm it, but it looks like this was the difference.

So let's say this is the difference and I prefer the ride of the Open Pro. What do you all think it is about the 2 different wheels that causes such a huge difference in handling? Weight? Lower spoke count? Stiffness?
In general, which of these 3 is more likely to make those Ultegras so "twitchy". They actually handle really well and are real comfortable, but I just need to decide if they are the ride I want on this bike. Some people may find the Ultegras nice and quick and the Open Pros kind of sluggish by comparison, so I know it's all subjective. But I'm curious which factors you think would have the biggest impact.
Rotational mass.

The two wheelsets are otherwise too similar in aerodynamics. A 16 spoke radial front shouldn't be much different in stiffness to a 32 3x.

[Richard]

Tire profile? Same tire?

[SteveV0983]

Tire profile? Same tire?

Same tire. Both are Fortezza TriComps. Granted the ones on the new wheels are brand new and the ones on the Open Pros have about 1400 miles on them, but both the same tire.

[Fixed]

In the old days everyone had a set of everyday training wheels and a set of racing wheels
Cheers

[tuscanyswe]

Glad to hear you got the bike feeling how you want it to feel, regardless of what was causing it.

I thought my moots had a very fast steering the first time i tried it. I got a couple of mm more rake than recommended by moots tho. I loved that feeling from the start even tho i too felt it wasent as stable as some of my previous bikes. Got used to it really fast and now i wouldent have it any other way. Makes it feel fast :)

[Louis]

Rotational mass.

I was thinking the same thing. It might be the gyroscopic effect.

How much difference in weight between the wheels? (Technically what you really need to compare is rotational inertia, but that's much harder to measure or calculate.)

[SteveV0983]

I was thinking the same thing. It might be the gyroscopic effect.

How much difference in weight between the wheels?

From what I can tell, the Ultegra front is listed as 695g. According to Colorado Cyclist, an Open Pro with an Ultegra 6700 hub is 878g (mine may be slightly heavier with older 6600 hubs). So if you use these figures, the Open Pro is 26% (183 g) heavier.

By the way, wouldn't the spoke count add to the rotational force? Seems to me 32 spokes would have more of a gyroscopic effect than 16.

[Kontact]

From what I can tell, the Ultegra front is listed as 695g. According to Colorado Cyclist, an Open Pro with an Ultegra 6700 hub is 878g (mine may be slightly heavier with older 6600 hubs). So if you use these figures, the Open Pro is 26% (183 g) heavier.

By the way, wouldn't the spoke count add to the rotational force? Seems to me 32 spokes would have more of a gyroscopic effect than 16.
Yes, and that's one of the reason the Open Pro wheel weighs more. The rims themselves probably aren't that different in weight.

[Germany_chris]

And you find a big handling difference when you use the dynamo hub vs an ordinary hub? I've swapped between dynamo and regular hubs on several of my bikes many times and have never felt any such thing. In fact, I have not even been able to detect the weight difference.

Me either..

[Chance]

I think the stiffness, responsiveness of the fork may play a big part.

Agree. Since tires are the same, of the items mentioned the fork probably makes biggest difference.

[Chance]

Raising the bars 2 or 3 cm makes very little difference to weight distribution.

Obviously having the bars higher or lower will make a significant change in how the bike feels, but it can't be from weight change since it doesn't change that much.

[sandyrs]

I having trouble believing it. You raise the bars let's say by 2 cm. That's a pretty big raise as far as handlebars are concerned. Does your weight distribution change as much as it does when you move from the hoods or the bar tops to the drops? No way. And yet, who notices a significant change in handling when you go from the hoods to the drops?

I do. Cornering while in the drops, at least on my race bike with a relatively short wheelbase, is noticeably more stable than cornering while on the hoods. The fact that the OP is using the same stem with the bars 3cm higher compounds this effect- since the head tube isn't vertical, moving the bars up doesn't only move his weight up; it also moves it back. This probably won't cause a huge change in handling, but I think it could cause enough of one to notice on an otherwise identical setup.

[Fixed]

I do. Cornering while in the drops, at least on my race bike with a relatively short wheelbase, is noticeably more stable than cornering while on the hoods. The fact that the OP is using the same stem with the bars 3cm higher compounds this effect- since the head tube isn't vertical, moving the bars up doesn't only move his weight up; it also moves it back. This probably won't cause a huge change in handling, but I think it could cause enough of one to notice on an otherwise identical setup.

I would have to agree
Cheers

[zandrrr]

I do. Cornering while in the drops, at least on my race bike with a relatively short wheelbase, is noticeably more stable than cornering while on the hoods. The fact that the OP is using the same stem with the bars 3cm higher compounds this effect- since the head tube isn't vertical, moving the bars up doesn't only move his weight up; it also moves it back. This probably won't cause a huge change in handling, but I think it could cause enough of one to notice on an otherwise identical setup.

I am currently going through an experimentation phase with my Serotta testing exactly this phenomenon. I have been alternating between two positions - position A: stem at the highest limit with 30mm of spacers underneath, and position B: stem slammed to the headset with 30mm spacers on top. The difference is staggering.

In position A, the bike is a bit squirrely, and I can tell my weight bias is towards the back. I have to be in the drops to do any sort of serious cornering. The bike does not feel stable when riding on the hoods.

In position B, the bike is much more stable and I can corner much better in both the drops and on the hoods. I feel like my weight is more evenly balanced over the middle of the bike, rather than towards the back.

Interestingly, one would think position A would be more comfortable; however, I am actually finding position B to be a bit more comfortable over long rides. My theory on this is that the lower position engages my core muscles in a way that the higher position does not, and therefore keeps me more stable, rather than supporting myself entirely by my arms and sitbones.

I'm still experimenting with this but I thought I would chime in. I have a feeling that my bike is set up in a way where the two positions lie on either side of an optimum, above which and below which changes don't make much difference. What I mean is, if I were able to position my bars higher than position A, I doubt the handling would be drastically different than in position A; were I able to lower them below B, I doubt the handling would be drastically different from B. But I do think there's a line, somewhere, that when crossed changes the handling dynamic significantly. Perhaps the OP is in the same position on his bike.

(Or perhaps this is all nonsense and I don't know what I'm talking about! :p)

[lhuerta]

The fact that the OP is using the same stem with the bars 3cm higher compounds this effect- since the head tube isn't vertical, moving the bars up doesn't only move his weight up; it also moves it back. This probably won't cause a huge change in handling, but I think it could cause enough of one to notice on an otherwise identical setup.

+1

This is a height and reach issue....30mm additional spacers/stem height is significant enough to change the riders height/reach position and change the handling of the bike. Use this stem length/height calculator to see the difference:

http://www.brightspoke.com/t/bike-stem-calculator.html

I really doubt the issue the OP is experiencing has anything to do with different wheels. Also, The OP has not told us what size stem he using. If he is already on a short stem, the decreased reach resulting from increased height of stem, will result in an even twitchier ride.

EM3

[SteveV0983]

OP here. Thanks for that insight zandrrr. I'm going to try swapping some of the spacers at some point and see what difference I find. The new bike is set up with 1.8cm saddle to bar drop, which is exactly how my old bike (a Serotta Colorado tg) was set up, so I'm used to sitting more upright. That being said, what you have found could certainly make a difference on a different bike. Although they are set up very close to each other, my weight may sit different on the Moots than it did on the Serotta (the Moots is a little longer bike).
Ilhuerta, I'm using a 100 mm stem, which is what I always used in the past and also what I used on the demo. See above for my thoughts on the bar height, although I do acknowlege that the same saddle-bar draop on 2 different bikes could behave different. But this is a pretty drastic steering difference.
All that being said, I did find that on a quick ride on my street, the Open Pro wheel seemed to correct the problem. I'll know more on my next ride when I use that wheel for the entire ride.
As another update, today I spoke to a couple of wheel builders and they seem to unanimously feel as though it is a weight issue (wheel weight, not my weight. Although that could have an affect also - I weight 175-180), probably caused by the lower spoke count (weight) on the new Ultegra wheels and the higher tension needed for the lower spoke count. Unfortunately, in a world of who-can-make-the-lightest-wheels, a set of stock ones that suit my taste may be tough to find. Maybe a low count, radial laced front wheel just isn't to my liking and I can find someone to build me up something nice with 28 or 32 spokes - something like Dura-Ace hubs and a Velocity A23 rim. Or something stock with a higher spoke count. That's assuming I can in fact prove it is the wheels, but as I mentioned, my short test ride seemed to lead me in this direction.

[Chance]

+1

This is a height and reach issue....30mm additional spacers/stem height is significant enough to change the riders height/reach position and change the handling of the bike. Use this stem length/height calculator to see the difference:

http://www.brightspoke.com/t/bike-stem-calculator.html

I really doubt the issue the OP is experiencing has anything to do with different wheels. Also, The OP has not told us what size stem he using. If he is already on a short stem, the decreased reach resulting from increased height of stem, will result in an even twitchier ride.

EM3

Why is it that in the "old" days when we used threaded-steerer quill stems and riders moved them up and down a bunch this issue didn't come up? Wasn't it the same? Reach was thought more as adding the top tube length plus stem length. There were no computer calculators, but the results were exactly the same. Moving stem up and down steerer was about the same, wasn't it?:confused:

[SteveV0983]

Why is it that in the "old" days when we used threaded-steerer quill stems and riders moved them up and down a bunch this issue didn't come up? Wasn't it the same? Reach was thought more as adding the top tube length plus stem length. There were no computer calculators, but the results were exactly the same. Moving stem up and down steerer was about the same, wasn't it?:confused:

Yes it was. You put the stem wherever the bars were comfortable and didn't have to be concerned with whether or not your spacer stack was acceptable to the masses. My Serotta had a quill stem and I moved it wherever I wanted it and never even knew what the height was. I put a piece of electrical tape on it at the headset so I would have a reference if I ever wanted to change it. Ahhh, the good ol' days.......

[Chance]

Yes it was. You put the stem wherever the bars were comfortable and didn't have to be concerned with whether or not your spacer stack was acceptable to the masses. My Serotta had a quill stem and I moved it wherever I wanted it and never even knew what the height was. I put a piece of electrical tape on it at the headset so I would have a reference if I ever wanted to change it. Ahhh, the good ol' days.......

Exactly. My question is why didn't people bring up the fact that when the stem was moved up or down it changed the weight distribution and therefore handling?:confused:

As stated above, my opinion is that moving the bars does change handling, but not because of weight distribution. If somebody can show just how much difference raising the bars 2 or 3 cm can make to weight distribution it would be interesting to see it. The numbers just don't support a significant concern because of this. Handling is affected for other reasons. Which is important of course. Not trying to contradict that. Just the cause of why it changes.

[palincss]

As stated above, my opinion is that moving the bars does change handling, but not because of weight distribution. If somebody can show just how much difference raising the bars 2 or 3 cm can make to weight distribution it would be interesting to see it. The numbers just don't support a significant concern because of this. Handling is affected for other reasons. Which is important of course. Not trying to contradict that. Just the cause of why it changes.

Could you be more specific about these changes? Can you describe how, exactly, handling changes? Is it measurable? There seem to be quite a few here who agree these changes are real. I wonder if there's also agreement on what the changes are.

It's certainly easy enough to measure the amount of change in fore-aft weight distribution: put the bike + rider on scales under front and rear wheels, then move hands from hoods to drops and see to what extent the readings on the scales change. Compare with the effect of adding weights in jersey pockets.

[Chance]

Could you be more specific about these changes? Can you describe how, exactly, handling changes? Is it measurable? There seem to be quite a few here who agree these changes are real. I wonder if there's also agreement on what the changes are.

It’s my opinion that when bars are moved up or down a significant amount it changes the range of motion that the rider’s muscles go through in order to steer the bike. Additionally, the rider’s leverage to turn the bars about the steering axis is not exactly the same. And it doesn’t take much change from what we feel comfortable with before the bike feels odd to us. The very same set-up may feel just fine to another rider, but we are not all the same. For me, bars that are too low make a bike hard to control with any precision. Would rather err on the high side compared to being too low. Obviously just right (to meet my preference) is best.

It's certainly easy enough to measure the amount of change in fore-aft weight distribution: put the bike + rider on scales under front and rear wheels, then move hands from hoods to drops and see to what extent the readings on the scales change. Compare with the effect of adding weights in jersey pockets.

Yes, testing or calculating is very easy. And both show that moving bars up or down a few cm doesn’t make much difference. Other factors can affect weight distribution a lot more than bar height.

[palincss]

It’s my opinion that when bars are moved up or down a significant amount it changes the range of motion that the rider’s muscles go through in order to steer the bike. Additionally, the rider’s leverage to turn the bars about the steering axis is not exactly the same. And it doesn’t take much change from what we feel comfortable with before the bike feels odd to us. The very same set-up may feel just fine to another rider, but we are not all the same. For me, bars that are too low make a bike hard to control with any precision. Would rather err on the high side compared to being too low. Obviously just right (to meet my preference) is best.


So, to paraphrase - I think you're saying it's not the handling of the bike itself that changes, it's the rider and the way the rider's body works. I think that's exactly right.

[Kontact]

It’s my opinion that when bars are moved up or down a significant amount it changes the range of motion that the rider’s muscles go through in order to steer the bike. Additionally, the rider’s leverage to turn the bars about the steering axis is not exactly the same. And it doesn’t take much change from what we feel comfortable with before the bike feels odd to us. The very same set-up may feel just fine to another rider, but we are not all the same. For me, bars that are too low make a bike hard to control with any precision. Would rather err on the high side compared to being too low. Obviously just right (to meet my preference) is best.



Yes, testing or calculating is very easy. And both show that moving bars up or down a few cm doesn’t make much difference. Other factors can affect weight distribution a lot more than bar height.

I think the main difference was that most people with quill stems were riding lower than the typical person with sloping top tubes and extended head tubes today. And I think that there is a range of positions that don't change the front end loading very much, and quill stems kept people well into that range. Current positions are much closer to the tipping point where weight starts to come off the front end more quickly per spacer added. Considering that the upper body bends in an arc from the saddle, this quick drop off could make sense.

[oldpotatoe]

From what I can tell, the Ultegra front is listed as 695g. According to Colorado Cyclist, an Open Pro with an Ultegra 6700 hub is 878g (mine may be slightly heavier with older 6600 hubs). So if you use these figures, the Open Pro is 26% (183 g) heavier.

By the way, wouldn't the spoke count add to the rotational force? Seems to me 32 spokes would have more of a gyroscopic effect than 16.

BUT the rim on the 16h wheel is heavier. Probably heavier than 16 spokes.

I think it may be wheel stiffness. Heavier rim=stiffer wheel.

I think rotational inertia differences or even weight on a many thousands gram rider and bike package is lost in the noise.

[SteveV0983]

BUT the rim on the 16h wheel is heavier. Probably heavier than 16 spokes.

I think it may be wheel stiffness. Heavier rim=stiffer wheel.

I think rotational inertia differences or even weight on a many thousands gram rider and bike package is lost in the noise.

Actually the 32h wheel is the heavier one (I know it may get confusing because they both have Ultegra somewhere on them). The OpenPro rim with Ultegra 6600 hub is the 878g, 32h rim. The Ultegra WH-6700 wheel is the 695g 16h wheel, so the 16h is the lighter of the two.
I agree that it may be wheel stiffness, and I think that the 32h Open Pro rim (the heavier one) is the less stiff of the two. From what I have learned, the Ultegra WH-6700 rim is a very strong and stiff rim, which is why they can build it with only 16 spokes and those spokes have to be at a very high tension. So the "twitchier" (some would say "more responsive") wheel seems to be the stiffer wheel with the higher tension, lower count spokes.
Does that sound like I'm on the right thinking track?

[Chance]

Actually the 32h wheel is the heavier one (I know it may get confusing because they both have Ultegra somewhere on them). The OpenPro rim with Ultegra 6600 hub is the 878g, 32h rim. The Ultegra WH-6700 wheel is the 695g 16h wheel, so the 16h is the lighter of the two.
I agree that it may be wheel stiffness, and I think that the 32h Open Pro rim (the heavier one) is the less stiff of the two. From what I have learned, the Ultegra WH-6700 rim is a very strong and stiff rim, which is why they can build it with only 16 spokes and those spokes have to be at a very high tension. So the "twitchier" (some would say "more responsive") wheel seems to be the stiffer wheel with the higher tension, lower count spokes.
Does that sound like I'm on the right thinking track?

Have you compared the two wheels for lateral stiffness? An aero rim wheel with fewer spokes may ride stiffer but is not necessarily stiffer side-to-side which should make a bigger difference to handling. Wheel stiffness is not just about which rim is stiffer, particularly when tested laterally. My 32-spoke OP rims on Ultegra hubs seem laterally stiffer (by hand pull testing only) than my lighter 16-spoke wheels. Yet they ride nicer too.

[SteveV0983]

Have you compared the two wheels for lateral stiffness? An aero rim wheel with fewer spokes may ride stiffer but is not necessarily stiffer side-to-side which should make a bigger difference to handling. Wheel stiffness is not just about which rim is stiffer, particularly when tested laterally. My 32-spoke OP rims on Ultegra hubs seem laterally stiffer (by hand pull testing only) than my lighter 16-spoke wheels. Yet they ride nicer too.

Interesting. Now I'm more confused than ever. Weather permitting, I'm hoping to get in a ride with the Open Pro on the front later today to at least see if I can definitively say it is the wheel that is causing the difference.
The OpenPro is a fairly old rim. Simply from a rim point of view, is there any way to know how it compares to newer rims as far as stiffness is concerned? Is the OpenPro considered a "stiff" rim?

[Chance]

Interesting. Now I'm more confused than ever. Weather permitting, I'm hoping to get in a ride with the Open Pro on the front later today to at least see if I can definitively say it is the wheel that is causing the difference.
The OpenPro is a fairly old rim. Simply from a rim point of view, is there any way to know how it compares to newer rims as far as stiffness is concerned? Is the OpenPro considered a "stiff" rim?

You shouldn't just look at "rim" data but at the complete wheel. Rim alone doesn't say much and will confuse you.

It's easy enough to grab the wheel/tire near the brake and move it side to side until it touches the brake pads. Then do the same with other wheel to see which one takes more force to move. Just make sure that rims are of same width otherwise you may be flexing one wheel further than the other and bias your "feel" results. It's probably best to open the brake's quick release so you have more movement before rim touches brake pad. Obvously if you ride with lots of pad clearance don't go nuts and damage your wheel(s) by moving them off center too far.

If you test one wheel right after the other you should be able to tell which one is stiffer (unless they are very similar, in which case it doesn't matter).

[SteveV0983]

It's easy enough to grab the wheel/tire near the brake and move it side to side until it touches the brake pads. Then do the same with other wheel to see which one takes more force to move. Just make sure that rims are of same width otherwise you may be flexing one wheel further than the other and bias your "feel" results. It's probably best to open the brake's quick release so you have more movement before rim touches brake pad. Obvously if you ride with lots of pad clearance don't go nuts and damage your wheel(s) by moving them off center too far.

If you test one wheel right after the other you should be able to tell which one is stiffer (unless they are very similar, in which case it doesn't matter).

Very interesting. I just tried this and I would have to say that the 32 spoke OpenPro are the laterally stiffer of the two. So if that's the case, maybe the 16 spoke fronts are just too flexy side to side and that's what's causing the steering difference. This certainly makes sense when you just look at the facts - double the spokes certainly should be stiffer side to side. Thanks for this.

[SteveV0983]

So I went for a ride yesterday and can confirm that it was the wheel that was causing the difference. For me, the OpenPro stayed on track better and was much more secure feeling. I guess stiffer and/or higher spoke count and/or heavier is what I'm looking for. Now if I can just narrow down which one it is......
Thanks for all your responses - not sure I would have ever figured it out without all these suggestions.