Above the stem
11-13-22, 03:23 PM
#1
Resident PIA
Thread Starter
Join Date: Jul 2004
Location: City of Oaks, NC
Posts: 848
Bikes: Gunnar Roadie, Look 765 Optimum, Spesh Aethos
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Liked 356 Times
in
186 Posts
Above the stem
What is the approved measurement for the amount of spacer above the stem?
As my core strength is improving I’ve started to move the stem down on the steerer tube, right now I am at a 10mm spacer above and 23mm below. I don’t want to cut the steerer more than once and think I’ll probably lower it some more but a don’t want to commit a BF faux pas.
.
As my core strength is improving I’ve started to move the stem down on the steerer tube, right now I am at a 10mm spacer above and 23mm below. I don’t want to cut the steerer more than once and think I’ll probably lower it some more but a don’t want to commit a BF faux pas.
.
__________________
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
11-13-22, 03:50 PM
#2
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,039
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22584 Post(s)
Liked 8,923 Times
in
4,156 Posts
If you are positive you like your position and positive you will not be selling the bike, enough for one small spacer, 5mm.
At 10mm you are close enough that only a meanie would say “down periscope” or “chimney” to you so I would leave it alone for now.
At 10mm you are close enough that only a meanie would say “down periscope” or “chimney” to you so I would leave it alone for now.
11-13-22, 04:19 PM
#3
Senior Member
Join Date: Jun 2021
Location: Australia
Posts: 823
Bikes: 2002 Trek 5200 (US POSTAL), 2020 Canyon Aeroad SL
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 313 Post(s)
Liked 680 Times
in
327 Posts
Most would say no spacer above or a 5mm spacer above at the most is the perfect look (and I tend to agree).
That said, I always stick with a 10mm above just in case I ever fancy/need more height at some point. Stick with what you've got. If you do lower later on, you can cut then.
That said, I always stick with a 10mm above just in case I ever fancy/need more height at some point. Stick with what you've got. If you do lower later on, you can cut then.
Likes For tempocyclist:
11-13-22, 04:24 PM
#4
Achtung!
Join Date: Oct 2015
Location: New England
Posts: 1,673
Bikes: 60.1, Marvel
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 515 Post(s)
Liked 268 Times
in
161 Posts
I moved my stem down and put the spacer over it. I don’t mind the look and it’s isn’t hurting anything by being there.
11-13-22, 04:50 PM
#5
Senior Member
Join Date: Feb 2018
Posts: 786
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 338 Post(s)
Liked 408 Times
in
252 Posts
A 2mm spacer is generally enough, and no spacers will work perfectly if the top cap is designed for it; the important bit is that the top cap can push "against" the stem.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
11-13-22, 05:09 PM
#6
Resident PIA
Thread Starter
Join Date: Jul 2004
Location: City of Oaks, NC
Posts: 848
Bikes: Gunnar Roadie, Look 765 Optimum, Spesh Aethos
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Liked 356 Times
in
186 Posts
A 2mm spacer is generally enough, and no spacers will work perfectly if the top cap is designed for it; the important bit is that the top cap can push "against" the stem.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
.
__________________
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
11-13-22, 05:43 PM
#7
should be more popular
We both ride slammed stems and all mechanics I ever spoke to when I get these chopped suggested to leave a 5mm spacer on top.
11-13-22, 06:10 PM
#8
Senior Member
Join Date: Feb 2018
Posts: 786
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 338 Post(s)
Liked 408 Times
in
252 Posts
If your bike comes with a top cap with an integrated spacer, or the stem and top cap are designed not to need one (many Specialized bikes) there's absolutely no need for 5mm spacer on top.
Not sure this makes sense to me, the steerer had the stem at the top with just enough gap to allow for proper preload and 33mm of spacers below. If I rearrange the order and move a 10mm spacer above the stem with a long enough compression plug what difference would it make? The compression is 40mm long and reaches below the top bearing.
.
.
Last edited by Branko D; 11-13-22 at 06:17 PM.
Likes For Branko D:
11-13-22, 07:43 PM
#9
Senior Member
Join Date: Apr 2007
Posts: 6,760
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1109 Post(s)
Liked 1,200 Times
in
760 Posts
A 2mm spacer is generally enough, and no spacers will work perfectly if the top cap is designed for it; the important bit is that the top cap can push "against" the stem.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
Anything more than 5mm is unnecessary, and tall spacer stacks above the stem prevent the compression plug (depending on it's length) from supporting the stem from inside, so with a spacer stack you will be clamping unsupported carbon, which is a bad idea and not how it was designed to work.
Likes For Camilo:
11-14-22, 01:05 AM
#10
Sunshine
Join Date: Aug 2014
Location: Des Moines, IA
Posts: 16,608
Bikes: '18 class built steel roadbike, '19 Fairlight Secan, '88 Schwinn Premis , Black Mountain Cycles Monstercross V4, '89 Novara Trionfo
Mentioned: 123 Post(s)
Tagged: 0 Thread(s)
Quoted: 10954 Post(s)
Liked 7,482 Times
in
4,184 Posts
Most would say no spacer above or a 5mm spacer above at the most is the perfect look (and I tend to agree).
That said, I always stick with a 10mm above just in case I ever fancy/need more height at some point. Stick with what you've got. If you do lower later on, you can cut then.
That said, I always stick with a 10mm above just in case I ever fancy/need more height at some point. Stick with what you've got. If you do lower later on, you can cut then.
Setting it up so the entire stem is below the top of the steerer tube means the stems full clamping force is completely on the steerer tube and none of it is pinching and pushing in the top of the steerer tube.
...or am I misunderstanding what you posted?
11-14-22, 01:37 AM
#11
Senior Member
Join Date: Feb 2018
Posts: 786
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 338 Post(s)
Liked 408 Times
in
252 Posts
No spacer above means the stem is tightened and the top of the steerer tube is impacted by the tightened stem. That seems less than ideal.
Setting it up so the entire stem is below the top of the steerer tube means the stems full clamping force is completely on the steerer tube and none of it is pinching and pushing in the top of the steerer tube.
Setting it up so the entire stem is below the top of the steerer tube means the stems full clamping force is completely on the steerer tube and none of it is pinching and pushing in the top of the steerer tube.
Not ideal
You'll notice the top (black) part of the compression plug doesn't actually expand, so without a spacer on top, the top bolt of the stem will, depending on location, clamp a partially unsupported bit. This type of steerer plug is also why a stack of spacers above is unwise if you haven't checked what sort of compression plug you've got; it's really short, so if you put 20mm of spacers above, the bottom bolt will clamp an unsupported bit. It's not a very good design, but it gets used.
This one is completely fine structurally without a spacer on top, and is longer meaning that with a spacer or two on top you'll still be fine nevertheless:
A much better design.
Last edited by Branko D; 11-14-22 at 03:33 AM.
Likes For Branko D:
11-14-22, 07:14 AM
#12
Resident PIA
Thread Starter
Join Date: Jul 2004
Location: City of Oaks, NC
Posts: 848
Bikes: Gunnar Roadie, Look 765 Optimum, Spesh Aethos
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Liked 356 Times
in
186 Posts
If we want to talk about structural integrity, the area where the bolts are must be supported adequately from inside by a compression plug for everything to be ideal. The reason why it's safer to recommend everyone leave a 5mm spacer are compression plugs like this one:
Not ideal
You'll notice the top (black) part of the compression plug doesn't actually expand, so without a spacer on top, the top bolt of the stem will, depending on location, clamp a partially unsupported bit. This type of steerer plug is also why a stack of spacers above is unwise if you haven't checked what sort of compression plug you've got; it's really short, so if you put 20mm of spacers above, the bottom bolt will clamp an unsupported bit. It's not a very good design, but it gets used.
This one is completely fine structurally without a spacer on top, and is longer meaning that with a spacer or two on top you'll still be fine nevertheless:
A much better design.
Not ideal
You'll notice the top (black) part of the compression plug doesn't actually expand, so without a spacer on top, the top bolt of the stem will, depending on location, clamp a partially unsupported bit. This type of steerer plug is also why a stack of spacers above is unwise if you haven't checked what sort of compression plug you've got; it's really short, so if you put 20mm of spacers above, the bottom bolt will clamp an unsupported bit. It's not a very good design, but it gets used.
This one is completely fine structurally without a spacer on top, and is longer meaning that with a spacer or two on top you'll still be fine nevertheless:
A much better design.
The wall thickness on my steerer tube is also at least 3/16s” thick carbon.
.
__________________
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
--
Shad
I knew where I was when I wrote this
I don't know where I am now...
05 Gunnar Roadie Chorus/Record
67'er
Likes For Shadco:
11-14-22, 09:56 AM
#13
• —
Join Date: Jun 2015
Location: Land of Pleasant Living
Posts: 12,222
Bikes: Shmikes
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 10154 Post(s)
Liked 5,849 Times
in
3,150 Posts
Being very old and riding a fairly amount of drop, I have left myself a cm in case of a sudden attack of decrepitude.
Likes For MoAlpha:
11-14-22, 11:39 AM
#14
I'm good to go!
Join Date: Jul 2017
Location: Mississippi
Posts: 14,977
Bikes: Tarmac Disc Comp Di2 - 2020
Mentioned: 51 Post(s)
Tagged: 0 Thread(s)
Quoted: 6187 Post(s)
Liked 4,803 Times
in
3,313 Posts
If you are happy with just putting the spacers you take off the bottom to lower the stem on top, then there is no need to cut the stem at all. It's not like I'm going to pass you on the road and that's the thing I'm going to notice about you and your bike.
But if you do have to cut it, and your steerer is carbon fiber, then the general advice is that the steerer should be at or above the top of the stem slightly and a spacer on top the stem. A 2 mm spacer is more than enough if it allows enough slack to be taken out of the headset bearings without the steerer tube touching the cap.
But if you do have to cut it, and your steerer is carbon fiber, then the general advice is that the steerer should be at or above the top of the stem slightly and a spacer on top the stem. A 2 mm spacer is more than enough if it allows enough slack to be taken out of the headset bearings without the steerer tube touching the cap.
11-15-22, 07:15 AM
#15
Senior Member
Join Date: Aug 2019
Location: Québec, Canada
Posts: 2,111
Bikes: SL8 Pro, TCR beater
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 983 Post(s)
Liked 583 Times
in
438 Posts
As long as your compression plug covers the stem area, you're fine. Aesthetically speaking, the less the better, that's for sure.
Likes For eduskator:
11-17-22, 09:15 AM
#16
your god hates me
Join Date: Apr 2006
Posts: 4,589
Bikes: 2016 Richard Sachs, 2010 Carl Strong, 2006 Cannondale Synapse
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1248 Post(s)
Liked 1,275 Times
in
705 Posts
Obscure trivia: Cannondale's "SI Integrated" carbon forks & headsets & expansion plugs etc (the hardware for which iirc is OEMd by FSA) explicitly state that you should not use any spacers above the stem. I haven't looked at their design to figure out why they are so emphatic about this point, but it's slathered all over their installation guides and owner's manuals enough times that I'm sure there's a reason either their design team, or their legal team, insisted this be stated unequivocally.
11-17-22, 09:27 AM
#17
Senior Member
Join Date: Feb 2018
Posts: 786
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 338 Post(s)
Liked 408 Times
in
252 Posts
Obscure trivia: Cannondale's "SI Integrated" carbon forks & headsets & expansion plugs etc (the hardware for which iirc is OEMd by FSA) explicitly state that you should not use any spacers above the stem. I haven't looked at their design to figure out why they are so emphatic about this point, but it's slathered all over their installation guides and owner's manuals enough times that I'm sure there's a reason either their design team, or their legal team, insisted this be stated unequivocally.
If this is the design:
https://images.bike24.net/media/366/i/mb/95/d5/51/cannondale-kp017-si-expander-by-fsa-1136668.jpg
I can see why. The expansion plug is very short so any spacers above and you are claimping an unsupported CF steerer, and the mechanism is made to preload the bearings without spacers.
Likes For Branko D:
11-18-22, 05:51 PM
#18
Method to My Madness
Join Date: Nov 2020
Location: Orange County, California
Posts: 3,645
Bikes: Trek FX 2, Cannondale Synapse, Cannondale CAAD4, Santa Cruz Stigmata GRX
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1940 Post(s)
Liked 1,464 Times
in
1,013 Posts
... Cannondale's "SI Integrated" carbon forks & headsets & expansion plugs etc (the hardware for which iirc is OEMd by FSA) explicitly state that you should not use any spacers above the stem. I haven't looked at their design to figure out why they are so emphatic about this point, but it's slathered all over their installation guides and owner's manuals enough times that I'm sure there's a reason either their design team, or their legal team, insisted this be stated unequivocally.
If this is the design:
https://images.bike24.net/media/366/...sa-1136668.jpg
I can see why. The expansion plug is very short so any spacers above and you are claimping an unsupported CF steerer, and the mechanism is made to preload the bearings without spacers.
If this is the design:
https://images.bike24.net/media/366/...sa-1136668.jpg
I can see why. The expansion plug is very short so any spacers above and you are claimping an unsupported CF steerer, and the mechanism is made to preload the bearings without spacers.
The Synapse also allows a generous 55 mm of spacers under the stem; I am using 50 mm (with a -8 degree stem). I have not seen any other bike with a carbon steerer which allows > 40 mm of spacers under the stem.
However, interestingly, in the manual 2017-2020 version of the Synapse, oms cd bk rd synapse disc en r1 134911.pdf (cannondale.com), the Compression Assembly does not support the top stem bolt, only the bottom stem bolt. See page 10.
Likes For SoSmellyAir:
