Experiment, results. long post

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3/31/2020 7:28 AM

So while riding a friends bike with a fl and tall bars I noticed it felt really good and started wondering if I had 2 identical bikes with the only difference was that one had a FL and the other a TL stem and the bars were proportionate so that they were the same height above the frame on both setups, if that would change the feel of how the bike handles or not. I decided to find out .. heres what I did. Current rig is a 49mm enduro stem with credence 9.25 bars. My stem sits directly on the bearing wedge so the effective rise above the bearings is 34mm. If I add the height of the bars (234.95mm) it gives me a total bar rise of 268.95mm from the top of the bearing.
So I found a 49mm fl stem with an 8mm rise. Add the height of a 10" bar (254mm) and you get 262mm.. add a 6.95 (7)mm spacer and it gives the same BAR rise of 268.95 as on my TL setup.
Essentially both bars rise the same height from the ground and have the same reach.
My discovery is that it DOES feel different! I can't explain why (bars are almost identical geo 11/3/28.5 and 11/1.5/30) first thing I noticed is that when spinning it literally does feel like you're lifting your bike from lower. When hopping it took a good 10 hops over a ledge to find the balance point where i was actually in.control of the bike and could predict exactly where every part would be throughout the jump.
Does anyone have any solid input on how this works or am I really just imagining things? I do kind of prefer it but I'll have to say I was surprised at how unfamiliar everything felt. I frequently change bars so I'm familiar with how different widths and geos affect riding but this was something I had not experienced before.

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3/31/2020 7:46 AM

A lower bb and slimmer pedals make your feet lower, effectively raising your bar height, and changing the feel. CS lengths and TT lengths also play a role as well, a longer CS and TT will require you to use more force to raise the front end. Head tube length also plays a role as a taller one is less tunable with spacers because the ht itself takes up the space. tire height could also effect front end height, but not by much, unless you have 1-3/8 tires and the other bike has 2.5 balloon tires.

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I like riding my bike.

3/31/2020 7:52 AM

regardless of rise, the bars on a front load are going to have a contact point closer to the head tube, and that's going to limit the lag between the force transferring from hands -> bars -> frame.

1.5" on each side of the bar is enough to make the bars feel larger/heavier/sluggish in turns, generally different. The change in geo is enough to require adjusting your hands/wrists slightly, whether its on purpose or subconsciously.

Certain bars will have more flex, more butted tubes, etc. Shorter bars will feel harder with stiffer contact points, larger bars will be a little more flexy. I notice even versions of the same bar can feel a little different.

IMO Shorter bars will almost always feel more "connected" to the bike.

As for user install issues, bars could be slightly forward/back depending, But the general jist is that the only thing you really matched here is the rise height. Everything else when working together is going to create a different feeling geo.

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3/31/2020 7:56 AM

bmxmanboy wrote:

A lower bb and slimmer pedals make your feet lower, effectively raising your bar height, and changing the feel. CS lengths and TT lengths also play a role as well, a longer CS and TT will require you to use more force to raise the front end. Head tube length also plays a role as a taller one is less tunable with spacers because the ht itself takes up the space. tire height could also effect front end height, but not by much, unless you have 1-3/8 tires and the other bike has 2.5 balloon tires.

Thanks for the input but I'm on my same bike. All I did was change my bars and stem. The bars are the exact same height above the ground and reach from the frame as the previous setup. The only difference is 1.5 degrees of upsweep on the bars. The bb, cs, hta, every single part is the same because I'm riding my same bike.

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3/31/2020 8:02 AM
Edited Date/Time: 3/31/2020 8:07 AM

Dad_Im_Pregnant wrote:

regardless of rise, the bars on a front load are going to have a contact point closer to the head tube, and that's going to limit the lag between the force transferring from hands -> bars -> frame.

1.5" on each side of the bar is enough to make the bars feel larger/heavier/sluggish in turns, generally different. The change in geo is enough to require adjusting your hands/wrists slightly, whether its on purpose or subconsciously.

Certain bars will have more flex, more butted tubes, etc. Shorter bars will feel harder with stiffer contact points, larger bars will be a little more flexy. I notice even versions of the same bar can feel a little different.

IMO Shorter bars will almost always feel more "connected" to the bike.

As for user install issues, bars could be slightly forward/back depending, But the general jist is that the only thing you really matched here is the rise height. Everything else when working together is going to create a different feeling geo.

Please read the post. I'm aware of how taller shorter bars affect riding. I am on taller bars but also on a lower rise stem so essentially the bars are the same height they were before. (I included the math to make it easier to understand this.) The stem has the same reach so it is not closer to the head tube either. Everything is the same except the upsweep. Like I also said, I'm very familiar with how 1 or 2 degrees will change how a bike feels as I do change this stuff often. What I found odd is that it did not feel anything like when I change bars normally. It was a whole.difderent leverage point when jumping it felt like. Also I use a digital meter to make sure the bars always sit at my preferred 2Β° forward slant.

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3/31/2020 8:26 AM

Dad_Im_Pregnant wrote:

regardless of rise, the bars on a front load are going to have a contact point closer to the head tube, and that's going to limit the lag between the force transferring from hands -> bars -> frame.

1.5" on each side of the bar is enough to make the bars feel larger/heavier/sluggish in turns, generally different. The change in geo is enough to require adjusting your hands/wrists slightly, whether its on purpose or subconsciously.

Certain bars will have more flex, more butted tubes, etc. Shorter bars will feel harder with stiffer contact points, larger bars will be a little more flexy. I notice even versions of the same bar can feel a little different.

IMO Shorter bars will almost always feel more "connected" to the bike.

As for user install issues, bars could be slightly forward/back depending, But the general jist is that the only thing you really matched here is the rise height. Everything else when working together is going to create a different feeling geo.

Sean_Goff wrote:

Please read the post. I'm aware of how taller shorter bars affect riding. I am on taller bars but also on a lower rise stem so essentially the bars are the same height they were before. (I included the math to make it easier to understand this.) The stem has the same reach so it is not closer to the head tube either. Everything is the same except the upsweep. Like I also said, I'm very familiar with how 1 or 2 degrees will change how a bike feels as I do change this stuff often. What I found odd is that it did not feel anything like when I change bars normally. It was a whole.difderent leverage point when jumping it felt like. Also I use a digital meter to make sure the bars always sit at my preferred 2Β° forward slant.

let's simplify this, using simpler numbers, because the specs don't matter, I just need to explain why you're riding completely different geos (despite the numbers being the same).

You have stem 1, that is 1i n rise, and is a front load, so you put 9in bars to make it a 10in rise in total
You have stem 2, that is 3 in rise and is a top load, so you put 7in bars to it a 10in rise in total

They can have the same reach, but the front load's clamping point is still going to be 1in closer to the head tube, which is going to make the bike feel more snappy, because it removes the lag in the transfer of force.

So of course you're going to have a different leverage point, because it's going to be based on where the stem clamps the bars.

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Come back with a warrant.

3/31/2020 8:39 AM

I'm not surprised it feels different. I think if you ride enough, any little change can make a difference in feel. I can feel my car rides a little different with my bike on the bike rack. I mean, I can feel it for sure. I can also tell when the air in the tires is getting lower than normal. Just from driving. I think if you do anything enough, you notice little changes.

I remember Broc Raiford on one of his bike checks saying he cuts the steerer tube down enough so that he doesn't need any spacers and the bars are closer to the head tube. He said something like it feels more solid. Or something like that. But then he uses taller bars. So it may be the same height as if he used a set of shorter bars and a normal positioning of the stem. I don't remember if he's using a front load stem. I thought it was a top load. So even that might make a difference. You would think it would be the same as using a front load stem with the longer steerer tube, not cut down....

Like everyone always says, it's all preference. My guess is people do a tweak and it feels right so they stick with it. Or it feels right for a while and then they try something different.

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Philippians 1:6 And I am sure of this, that he who began a good work in you will bring it to completion at the day of Christ Jesus. Insta: SilentNightSun

3/31/2020 9:51 AM

too trivial to worry about. everything will feel different because everything is in fact different.

build two Identical bikes and they will feel different. i promise.

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3/31/2020 9:59 AM

less thinking . more riding.

* I say this as a numbers nerd..

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3/31/2020 1:40 PM

I like it like this: more thinking, more riding. smile They don't have to be mutually exclusive. Nothing wrong with discussing theories and geometry of bikes, IMHO.

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Philippians 1:6 And I am sure of this, that he who began a good work in you will bring it to completion at the day of Christ Jesus. Insta: SilentNightSun

3/31/2020 2:09 PM
Edited Date/Time: 3/31/2020 2:09 PM

Dad_Im_Pregnant wrote:

regardless of rise, the bars on a front load are going to have a contact point closer to the head tube, and that's going to limit the lag between the force transferring from hands -> bars -> frame.

1.5" on each side of the bar is enough to make the bars feel larger/heavier/sluggish in turns, generally different. The change in geo is enough to require adjusting your hands/wrists slightly, whether its on purpose or subconsciously.

Certain bars will have more flex, more butted tubes, etc. Shorter bars will feel harder with stiffer contact points, larger bars will be a little more flexy. I notice even versions of the same bar can feel a little different.

IMO Shorter bars will almost always feel more "connected" to the bike.

As for user install issues, bars could be slightly forward/back depending, But the general jist is that the only thing you really matched here is the rise height. Everything else when working together is going to create a different feeling geo.

Sean_Goff wrote:

Please read the post. I'm aware of how taller shorter bars affect riding. I am on taller bars but also on a lower rise stem so essentially the bars are the same height they were before. (I included the math to make it easier to understand this.) The stem has the same reach so it is not closer to the head tube either. Everything is the same except the upsweep. Like I also said, I'm very familiar with how 1 or 2 degrees will change how a bike feels as I do change this stuff often. What I found odd is that it did not feel anything like when I change bars normally. It was a whole.difderent leverage point when jumping it felt like. Also I use a digital meter to make sure the bars always sit at my preferred 2Β° forward slant.

Dad_Im_Pregnant wrote:

let's simplify this, using simpler numbers, because the specs don't matter, I just need to explain why you're riding completely different geos (despite the numbers being the same).

You have stem 1, that is 1i n rise, and is a front load, so you put 9in bars to make it a 10in rise in total
You have stem 2, that is 3 in rise and is a top load, so you put 7in bars to it a 10in rise in total

They can have the same reach, but the front load's clamping point is still going to be 1in closer to the head tube, which is going to make the bike feel more snappy, because it removes the lag in the transfer of force.

So of course you're going to have a different leverage point, because it's going to be based on where the stem clamps the bars.

If the reach is the same, the clamping point is the same relative to the fork (reach being the horizontal stem measurement, not distance to the grips).

The only reasonable difference I see is in the second post, the " 2Β° forward slant." If the bars are parallel to the fork, I would expect no real difference in these setups other than flex. If the bars are canted forward, then the pivot point starts lower and the longer bars reach further, putting the grips further away and changing the effective leverage at the grips, which might be enough to notice.

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Remember when you could ride all day and not be sore for a week?

3/31/2020 3:24 PM

So what I've gathered so far is: different bike be different like that.

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Scooter kid trying to ride BMX.
Instagram: @scootereyn

3/31/2020 3:32 PM

It's actually pretty hard to get bar position in the exact same spot, even just adding spacers under the stem you are effectively moving the bars back without actually adjusting them in the stem.

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3/31/2020 5:12 PM

Here are some pics for comparison. To show that both give the bars the same rise.
Today I rode with the FL setup for about an hour then switched to the TL And it feels 100% like you're riding a different bike. Super different! Same stem reach, and bar height above the frame. The main difference I noticed was that with the FL, it felt like my front end was longer and also more draggy, like I had to fight more to get it to do stuff. With the TL the immediate difference was how it feels like every motion puts more energy into what's happening. Like everything happened faster and with more positive energy. Almost twitchy, but everything felt easier and more precise. I 100% prefer TL. I don't know why it happens and there's a lot of good input on here, but I do know that its (illogically) a dramatically different feeling. Literally feels like you're riding a different bike.
Photo
Photo
Photo

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3/31/2020 8:24 PM

You have to fight it to get it to do stuff?

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3/31/2020 8:31 PM

Photo
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4/1/2020 8:06 AM

Spongeworthy wrote:

You have to fight it to get it to do stuff?

It seems to work. πŸ˜‚πŸ˜‚πŸ˜‚

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4/1/2020 8:09 AM

Don't know how it all works but I'll have say I was surprised by the results.
If you've wondered which style stem would work for you and have the ability to, give this a try.

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4/1/2020 8:14 AM

Sean_Goff wrote:

Please read the post. I'm aware of how taller shorter bars affect riding. I am on taller bars but also on a lower rise stem so essentially the bars are the same height they were before. (I included the math to make it easier to understand this.) The stem has the same reach so it is not closer to the head tube either. Everything is the same except the upsweep. Like I also said, I'm very familiar with how 1 or 2 degrees will change how a bike feels as I do change this stuff often. What I found odd is that it did not feel anything like when I change bars normally. It was a whole.difderent leverage point when jumping it felt like. Also I use a digital meter to make sure the bars always sit at my preferred 2Β° forward slant.

Dad_Im_Pregnant wrote:

let's simplify this, using simpler numbers, because the specs don't matter, I just need to explain why you're riding completely different geos (despite the numbers being the same).

You have stem 1, that is 1i n rise, and is a front load, so you put 9in bars to make it a 10in rise in total
You have stem 2, that is 3 in rise and is a top load, so you put 7in bars to it a 10in rise in total

They can have the same reach, but the front load's clamping point is still going to be 1in closer to the head tube, which is going to make the bike feel more snappy, because it removes the lag in the transfer of force.

So of course you're going to have a different leverage point, because it's going to be based on where the stem clamps the bars.

MJbmx wrote:

If the reach is the same, the clamping point is the same relative to the fork (reach being the horizontal stem measurement, not distance to the grips).

The only reasonable difference I see is in the second post, the " 2Β° forward slant." If the bars are parallel to the fork, I would expect no real difference in these setups other than flex. If the bars are canted forward, then the pivot point starts lower and the longer bars reach further, putting the grips further away and changing the effective leverage at the grips, which might be enough to notice.

Yes, except you're forgetting that one will be clamped slightly higher. Using arbitrary numbers:

If you have 2 stems with a reach of 1 inch, they will both be clamped 1inch from the fork in front. But since their rises are separate, one them will be clamped higher. Which still changes the leverage. Something clamped directly parallel will have a snappier leverage, than something clamped parallel and higher up.

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Come back with a warrant.

4/1/2020 8:15 AM

MJbmx wrote:

If the reach is the same, the clamping point is the same relative to the fork (reach being the horizontal stem measurement, not distance to the grips).

The only reasonable difference I see is in the second post, the " 2Β° forward slant." If the bars are parallel to the fork, I would expect no real difference in these setups other than flex. If the bars are canted forward, then the pivot point starts lower and the longer bars reach further, putting the grips further away and changing the effective leverage at the grips, which might be enough to notice.

Good point. I have however been riding bmx and trying different parts and bar angles etc for years and am quite familiar with how pushing bars a degree forward or back affects the riding feel but what you feel when doing this doesn't feel at all like you're just pushing the bars .25" forward or back. The balance point on the bike and how it responds is DRAMATICALLY different.

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4/1/2020 8:17 AM

Dad_Im_Pregnant wrote:

Yes, except you're forgetting that one will be clamped slightly higher. Using arbitrary numbers:

If you have 2 stems with a reach of 1 inch, they will both be clamped 1inch from the fork in front. But since their rises are separate, one them will be clamped higher. Which still changes the leverage. Something clamped directly parallel will have a snappier leverage, than something clamped parallel and higher up.

My experience has been that the higher rise gives a snappier feel. And the lower rise gave a sluggish feel. If you're in chicagoland, and coronavirus free, I'd be happy to let you try both bar setups on your own bike for a first hand experience. πŸ‘Š

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4/1/2020 8:20 AM

Sean_Goff wrote:

My experience has been that the higher rise gives a snappier feel. And the lower rise gave a sluggish feel. If you're in chicagoland, and coronavirus free, I'd be happy to let you try both bar setups on your own bike for a first hand experience. πŸ‘Š

snappier probably isn't the right word

and nope, i:m in MA, but I'm also 6'0 and ride Bobs on a FL, so you don't want my opinion on feel. I'm just speaking from basic physics at this point.

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4/1/2020 10:57 AM

Dad_Im_Pregnant wrote:

snappier probably isn't the right word

and nope, i:m in MA, but I'm also 6'0 and ride Bobs on a FL, so you don't want my opinion on feel. I'm just speaking from basic physics at this point.

It did feel more snappy but maybe funky, wonky would work too lol, I dunno. You'd have to try it yourself to diagnose the word. πŸ˜‚

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4/1/2020 8:32 PM

Dad_Im_Pregnant wrote:

Yes, except you're forgetting that one will be clamped slightly higher. Using arbitrary numbers:

If you have 2 stems with a reach of 1 inch, they will both be clamped 1inch from the fork in front. But since their rises are separate, one them will be clamped higher. Which still changes the leverage. Something clamped directly parallel will have a snappier leverage, than something clamped parallel and higher up.

The leverage of each piece will be different based on the clamp location, but assuming that both assemblies are rigid and the ends are in the same spot, the resulting forces at the ends will be the same. Think of it as a truss or bracket where the shape doesn't matter as long as it can handle the forces involved. It could be a long fork tube with little 4" trials bars welded to the top, as long as it puts the grips in the same spot relative to the head tube.

Change the angle away from parallel though, and that changes the end points, which changes the leverage. It would also change the swing of the bars in a turn. That's why I think the angle might explain the difference here.

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Remember when you could ride all day and not be sore for a week?

4/1/2020 8:37 PM

If you had a frontload with a 5 inch drop and bars that were 15 inches high, and a frontload with a 5 inch rise with 5 inch bars they would both have the same rise but feel completely different because of the leverage you have on the two setups.

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I like riding my bike.

4/3/2020 7:25 AM

MJbmx wrote:

The leverage of each piece will be different based on the clamp location, but assuming that both assemblies are rigid and the ends are in the same spot, the resulting forces at the ends will be the same. Think of it as a truss or bracket where the shape doesn't matter as long as it can handle the forces involved. It could be a long fork tube with little 4" trials bars welded to the top, as long as it puts the grips in the same spot relative to the head tube.

Change the angle away from parallel though, and that changes the end points, which changes the leverage. It would also change the swing of the bars in a turn. That's why I think the angle might explain the difference here.

So not to sound contradictory but that was my original assumption that it would be unnoticeable if my hands were in the same spot on both setups. It doesn't feel like my bars are further forward or back on my bike I've been biking a long time and I know what that feels like. This is not the same. The timing for all tricks, where your weight sits, everything, happens a lot different with the different setups. That's what the purpose of this post was, so that anyone else wondering the same could hear what happens in a real life case without having to do all the testing themself. Those were my findings, I stand by them, I would reccomend trying it yourself if you want to analyze it more but it really does not produce the same.effect at all.

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4/4/2020 8:49 AM

Sean_Goff wrote:

So not to sound contradictory but that was my original assumption that it would be unnoticeable if my hands were in the same spot on both setups. It doesn't feel like my bars are further forward or back on my bike I've been biking a long time and I know what that feels like. This is not the same. The timing for all tricks, where your weight sits, everything, happens a lot different with the different setups. That's what the purpose of this post was, so that anyone else wondering the same could hear what happens in a real life case without having to do all the testing themself. Those were my findings, I stand by them, I would reccomend trying it yourself if you want to analyze it more but it really does not produce the same.effect at all.

Perception is reality, so if you feel a difference then ride whichever you prefer. That said, from an engineering standpoint your assumptions sounded right to me, so I would question the results and look for other variables. I think the bar tilt could be one issue, and maybe the different bar width and upsweep as well.

You were very specific about the tilt angle, and the taller bar setup would be like tilting another 1.5 to 2 degrees forward. Adding to that, the taller bars flatten the upsweep and increase the width. Sounds like a combo for a less natural wrist position, with your grip being slightly more forward, flatter, wider, and probably higher as well (the shoulder of the bar might be higher with the shallow upsweep, can't tell from your pics). It's all probably within 1/4" or so each way, and you could get used to either, but switching might be noticeably different.

I'm not trying to be argumentative either, I'm just glad to have something other than work and plague to think about - it's been a long week. It was an interesting experiment either way, thanks for posting.

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Remember when you could ride all day and not be sore for a week?

4/4/2020 9:19 AM

bmxmanboy wrote:

If you had a frontload with a 5 inch drop and bars that were 15 inches high, and a frontload with a 5 inch rise with 5 inch bars they would both have the same rise but feel completely different because of the leverage you have on the two setups.

Not to drag this out or be a troll, but I feel like you're not thinking it all the way through.

The two points of interest for leverage are the grips (where you apply force to the bike) and the head tube (where the frame interacts with the steering column). The path between those two points literally doesn't matter, as long as the assembly is rigid enough. In your example, the added leverage that the 15" bars apply *at the stem* is completely offset by the path back up the stem to the fork, and down that to the head tube. Likewise, the 5" bars would work with the taller stem to provide the same resulting leverage at the head tube.

If you are in the market for new bars and / or stem for more leverage, the main concern is the final location of grips relative to head tube, because that is what provides the leverage. This is basic physics, and we could draw force diagrams and calculate loads at each piece to prove this out.

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Remember when you could ride all day and not be sore for a week?