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Adjustable Stem Question

Old 04-05-22, 09:45 AM
  #26  
nathand
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Originally Posted by TheFort View Post
I asked the maker of the stem about the compression issue, and they said, "You need a star nut in the steering tube"

Does anyone know what this means? I know what a star nut is, but I don't know what they mean. Are they saying you replace the hex nut on the compression plug with a star nut? I guess I can ask, but they don't seem to want to help.
A metal steerer tube has a star nut in it. Rather than using a compression plug, the bolt through the top cap screws into the star nut, which is held securely in the steerer. This creates compression on the bearings. You don't use a star nut in a carbon steerer because the sharp edges dig into the carbon.

You might be able to replace the bolt through your existing compression plug, with the bolt that's provided with the adjustable stem. If you can do that, the whole system will likely work fine, with the compression plug working normally.
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Old 04-05-22, 09:48 AM
  #27  
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Originally Posted by nathand View Post
A metal steerer tube has a star nut in it. Rather than using a compression plug, the bolt through the top cap screws into the star nut, which is held securely in the steerer. This creates compression on the bearings. You don't use a star nut in a carbon steerer because the sharp edges dig into the carbon.

You might be able to replace the bolt through your existing compression plug, with the bolt that's provided with the adjustable stem. If you can do that, the whole system will likely work fine, with the compression plug working normally.
That's exactly what I was looking for, thank you. Wondered if I could replace the bolt in the current plug with the bolt on their stem specifically, so thanks! It probably depends how long that bolt is because it would have to reach the bottom of the compression plug.
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Old 04-05-22, 09:56 AM
  #28  
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Originally Posted by TheFort View Post
But these stems have a built-in bolt in them that would bump into the compression plug in the steerer tube. That's the issue, unless I'm missing something.
I don't see that at all. The bolt is well outside the the stem- partway up it and you can rotate the upper part of the stem up or down and then tighten the bolt.
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Old 04-05-22, 09:59 AM
  #29  
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You need a stem that has no extension built into in. The Satori has an extension and shouldn't be used on carbon, per the bike mfg. You preload the same as with any threadless stem.

https://www.amazon.com/Kalloy-Adjust.../dp/B07QKXLFQK

If this is not going to get the bars high enough, then you need to swap out your fork for one with an aluminum (steel?) steerer.

John
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Old 04-05-22, 10:01 AM
  #30  
TheFort
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Originally Posted by Chandne View Post
I don't see that at all. The bolt is well outside the the stem- partway up it and you can rotate the upper part of the stem up or down and then tighten the bolt.
Maybe it wasn't clear in those photos.
Here's an image of a different stem but the same style, and you can see the bolt that's the problem:

https://m.media-amazon.com/images/I/...AC_SL1010_.jpg

I wonder if you could just remove that bolt entirely, use the compression plug in the steerer, and slide this over it and tight the side bolts...
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Old 04-05-22, 10:03 AM
  #31  
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Originally Posted by 70sSanO View Post
You need a stem that has no extension built into in. The Satori has an extension and shouldn't be used on carbon, per the bike mfg. You preload the same as with any threadless stem.

https://www.amazon.com/Kalloy-Adjust.../dp/B07QKXLFQK

If this is not going to get the bars high enough, then you need to swap out your fork for one with an aluminum (steel?) steerer.

John
Thanks. Makes sense. Wish they made them in 90 degrees then I wouldn't have to look at these other style ones.
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Old 04-05-22, 10:13 AM
  #32  
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This is the highest angle one I could find, and it's what is currently on my bike. It says +85 degrees, but it's more like +70 degrees. Still an improvement over my +60 degree one that this replaced, and the added stack gets me really close to a touring position. I'd like just a little more hence looking into these other ones.

https://www.amazon.com/dp/B09C4JTX2Z...roduct_details
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Old 04-05-22, 10:25 AM
  #33  
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Originally Posted by TheFort View Post
I wonder if you could just remove that bolt entirely, use the compression plug in the steerer, and slide this over it and tight the side bolts...
No. The spacers are an integral part of the system; the outside edges of the top cap push down on the spacers or the stem, not on the steerer tube. The adjustable stem here slides over the steerer tube in the same way the spacers do, and functions as the combination of spacers, stem, and top cap. It would be impossible to get the stem over the existing top cap, and if you could you wouldn't be able to achieve proper compression of the bearings.
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Old 04-05-22, 10:29 AM
  #34  
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Originally Posted by nathand View Post
No. The spacers are an integral part of the system; the outside edges of the top cap push down on the spacers or the stem, not on the steerer tube. The adjustable stem here slides over the steerer tube in the same way the spacers do, and functions as the combination of spacers, stem, and top cap. It would be impossible to get the stem over the existing top cap, and if you could you wouldn't be able to achieve proper compression of the bearings.
Ah, yeah, correct. I'll just give up on this and pray they make a regular non-riser stem in 90 degrees soon!
Thanks everyone.
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Old 04-05-22, 10:32 AM
  #35  
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One thing to keep in mind is that a 90 degree stem is going to significantly change the way the bike handles. With a stem like that, the bike is going to feel very twitchy
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Old 04-05-22, 10:33 AM
  #36  
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Originally Posted by TheFort View Post
This is the highest angle one I could find, and it's what is currently on my bike. It says +85 degrees, but it's more like +70 degrees. Still an improvement over my +60 degree one that this replaced, and the added stack gets me really close to a touring position. I'd like just a little more hence looking into these other ones.

https://www.amazon.com/dp/B09C4JTX2Z...roduct_details
I can't vouch for 70* vs 85*, but your head tube angle does add to the angle; even if that is not a part of listed stem angles.

I imagine you are going to pick up a 2cm or 3cm of height over your 60* (didn't calculate, just guessing). If that doesn't work, and you are able to talk to the bike mfg, they may be able to recommend a fork with a longer aluminum steerer tube that will extend further than your carbon steerer.

John
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Old 04-05-22, 10:34 AM
  #37  
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So you are trying to put an adjustable riser stem on a carbon steerer.
The problem you forsee is how to set the bearing preload on the headset upon installation. This is a valid concern. My guess is that this type of stem is designed for a fork with an aluminum steerer and internal starnut.
Without the internal starnut in the steerer tube, there will be nothing to pull the steerer up into the new riser stem and you will end up with a loose headset. There is almost certainly a bolt in the riser stem that is designed to thread into a starnut to accomplish the task of bearing adjustment of the headset.
Could you leave your current carbon expansion plug in place and modify it for use with the new stem? I see one potential option which requires the altering the top cap diameter of the expansion plug. For this to work, the top cap diameter would need to be reduced to match (or just a hair smaller) the outside diameter of the carbon steerer. This would allow the sleeve of the riser stem to slip over both the top cap and steerer as intended.
The question is whether or not the threading and pitch of the stem bolt designed to interface with the star nut will also be able to replace the original bolt of the expander plug in the carbon steerer. This will have to be sorted before everything is put together, as the expansion plug will need to be assembled to this bolt in a relaxed position, and inserted into the steerer as the the riser stem is slipped over the outside of the steerer, all as one piece, making sure the expansion plug is pushed in flush with the top of the steerer tube. Once this is all put onto the steerer, you should be able to tighten the bolt, expanding the plug, pulling up the fork crown, compressing the headset bearings, and finally tightening the stem bolts.
Whether or not this is a good idea putting the extra leverage on a carbon steerer is debatable. You might be better served trying to find a traditional (non-adjustable) stem with as much rise as possible to avoid this mess of alterations to the system.

Last edited by SalsaShark; 04-05-22 at 07:00 PM.
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Old 04-05-22, 10:38 AM
  #38  
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Originally Posted by 70sSanO View Post
I can't vouch for 70* vs 85*, but your head tube angle does add to the angle; even if that is not a part of listed stem angles.

I imagine you are going to pick up a 2cm or 3cm of height over your 60* (didn't calculate, just guessing). If that doesn't work, and you are able to talk to the bike mfg, they may be able to recommend a fork with a longer aluminum steerer tube that will extend further than your carbon steerer.

John
Interesting, I wrote the maker over the weekend and asked about that, but I asked if they could do an un-cut carbon fork. Does it have to be metal to go higher?
The head tube angle is 71.5 degrees. My position is pretty good right now. I'd say I'm in a moderate touring position. It's a gravel bike, and I want to set it up to be touring/gravel. Super close but just not quite right now.
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Old 04-05-22, 10:40 AM
  #39  
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https://www.amazon.com/Adjustable-De...NrPXRydWU&th=1
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Old 04-05-22, 10:40 AM
  #40  
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Originally Posted by SalsaShark View Post
So you are trying to put an adjustsble riser stem on a carbon steerer.
The problem you forsee is how to set the bearing preload on the headset unon installation. This is a valid concern. My guess is that this type of stem is designed for a fork with an aluminum steerer and internal starnut.
Without the internal starnut in the steerer tube, there will be nothing to pull the steerer up into the new riser stem and you will end up with a loose headset. There is almost certainly a bolt in the riser stem that is designed to thread into a starnut to accomplish the task of bearing adjustment of the headset.
Could you leave your current carbon expansion plug in place and modify it for use with the new stem? I see one potential option which requires the altering the top cap diameter of the expansion plug. For this to work, the top cap diameter would need to be reduced to match (or just a hair smaller) the outside diameter of the carbon steerer. This would allow the sleeve of the riser stem to slip over both the top cap and steerer as intended.
The question is whether or not the threading and pitch of the stem bolt designed to interface with the star not will also be able to replace the original bolt of the expander plug in the carbon steerer. This will have to be sorted before everything is put together, as the expansion plug will need to be assembled to this bolt in a relaxed position, and inserted into the steerer as the the riser stem is slipped over the outside of the steerer, all as one piece, making sure the expansion plug is pushed in flush with the top of the steerer tube. Once this is all put onto the steerer, you should be able to tighten the bolt, expanding the plug, pulling up the fork crown, compressing the headset bearings, and finally tightening the stem bolts.
Whether or not this is a good idea putting the extra leverage on a carbon steerer is debatable. You might be better served trying to find a traditional (non-adjustable) stem with as much rise as possible to avoid this mess of alterations to the system.
Great comment, thank you. I'll consider that. Regarding your last sentence, that's exactly why I did. I found a 70 degree. It will have to do for now...until the bike industry realizes people want to ride bikes in different ways. : D
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Old 04-05-22, 10:42 AM
  #41  
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That one is only 60 degrees. In a few posts above, I said I did find one that's 70 degrees (claimed 85) and linked to it. So the 60 degree would be a downgrade. But thank you for looking around.

If anyone bumps into an adjustable over 70 degrees in future internet surfing, please come back here and link to it!
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Old 04-05-22, 11:00 AM
  #42  
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Originally Posted by TheFort View Post
Interesting, I wrote the maker over the weekend and asked about that, but I asked if they could do an un-cut carbon fork. Does it have to be metal to go higher?
From what I've seen of carbon forks, there's a maximum number of spacers allowed between the bearing and the stem. I assume if you go higher you risk breaking the steerer. I haven't seen a similar limit on a metal fork. You could try gluing in a metal insert as described here: https://www.velonews.com/gear/techni...-stack-height/
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Old 04-05-22, 11:10 AM
  #43  
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Originally Posted by TheFort View Post
That one is only 60 degrees. In a few posts above, I said I did find one that's 70 degrees (claimed 85) and linked to it. So the 60 degree would be a downgrade. But thank you for looking around.

If anyone bumps into an adjustable over 70 degrees in future internet surfing, please come back here and link to it!
I was actually trying to show you what I have seen, as far as adjustable stems goo. That is the kind my friend uses too, and has just a traditional step type of fit. You can play with spacers to get a bigger rise, as well as riser drop bars to get another 10mm-20mm rise. Just ideas...a new bike fit may be very useful.
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Old 04-05-22, 11:28 AM
  #44  
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By the way, I use an Excel comparison tool to see how diff items and bars affect the hand position. I have used it a lot and it helps to see exactly how diff changes affect your position.
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