Explain Like I'm 5: Don't I need a compression plug to oppose the stem bolt forces?
#26
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,043
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22586 Post(s)
Liked 8,924 Times
in
4,157 Posts
My understanding is that star nuts are ok for metal/alloy steerer tubes but no bueno for crabon fiber steerer tubes. Again, I believe this is "conventional wisdom" but have zero "proof." It does make sense because a star nut would possibly cut into carbon while the expansion plug won't.
#27
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,043
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22586 Post(s)
Liked 8,924 Times
in
4,157 Posts
#28
working on my sandal tan
Join Date: Aug 2011
Location: CID
Posts: 22,629
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3871 Post(s)
Liked 2,568 Times
in
1,579 Posts
#29
Full Member
#30
What happened?
Join Date: Jun 2007
Location: Around here somewhere
Posts: 7,927
Bikes: 3 Rollfasts, 3 Schwinns, a Shelby and a Higgins Flightliner in a pear tree!
Mentioned: 57 Post(s)
Tagged: 1 Thread(s)
Quoted: 1835 Post(s)
Liked 292 Times
in
255 Posts
If I did that the answer would be something like I'm sure that your father has taken care of that.
__________________
I don't know nothing, and I memorized it in school and got this here paper I'm proud of to show it.
#31
• —
Join Date: Jun 2015
Location: Land of Pleasant Living
Posts: 12,224
Bikes: Shmikes
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 10159 Post(s)
Liked 5,849 Times
in
3,150 Posts
#33
climber has-been
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,101
Bikes: Scott Addict R1, Felt Z1
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3425 Post(s)
Liked 3,561 Times
in
1,790 Posts
Likes For terrymorse:
#34
Zoom zoom zoom zoom bonk
Join Date: Sep 2006
Location: New Zealand
Posts: 4,624
Bikes: Giant Defy, Trek 1.7c, BMC GF02, Fuji Tahoe, Scott Sub 35, Kona Rove, Trek Verve+2
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 551 Post(s)
Liked 722 Times
in
366 Posts
I'm guessing a crabon tube that maybe needs a compression plug is heavier than an alooooominum tube with a star nut.
For years I ran a MTB without a top cap or star nut because the steerer tube was stuffed with lighting electronics. Yes, it is perfectly safe, but not idiot proof so maybe the 41 shouldn't go there.
For years I ran a MTB without a top cap or star nut because the steerer tube was stuffed with lighting electronics. Yes, it is perfectly safe, but not idiot proof so maybe the 41 shouldn't go there.
#35
Senior Member
Join Date: Jul 2018
Location: USA
Posts: 2,190
Bikes: Ti, Mn Cr Ni Mo Nb, Al, C
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 942 Post(s)
Liked 526 Times
in
349 Posts
No the top cap does not sit flush on top of the steerer. In the video you posted the guy is talking about compression plugs which have a lip that sits on top of the steerer. The cap needs 2-3mm of space to compress the headset to spec. He was just demonstrating how the compression fitting can expand the steerer. He just happened to have the top cap attached in the demo. If it were on the bike there would be 2-3mm of space in order to adjust the headset.
Last edited by jadocs; 09-20-19 at 08:23 PM.
#36
bike whisperer
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,545
Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1526 Post(s)
Liked 718 Times
in
510 Posts
Your bars and seatpost aren't clamped on the end of the tube. Haven't you seen carbon bars deformed where the stem clamps them?
__________________
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
#37
Senior Member
Join Date: Sep 2011
Posts: 4,764
Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 1975 Post(s)
Liked 232 Times
in
173 Posts
No the top cap does not sit flush on top of the steerer. In the video you posted the guy is talking about compression plugs which have a lip that sits on top of the steerer. The cap needs 2-3mm of space to compress the headset to spec. He was just demonstrating how the compression fitting can expand the steerer. He just happened to have the top cap attached in the demo. If it were on the bike there would be 2-3mm of space in order to adjust the headset.
#39
What happened?
Join Date: Jun 2007
Location: Around here somewhere
Posts: 7,927
Bikes: 3 Rollfasts, 3 Schwinns, a Shelby and a Higgins Flightliner in a pear tree!
Mentioned: 57 Post(s)
Tagged: 1 Thread(s)
Quoted: 1835 Post(s)
Liked 292 Times
in
255 Posts
As an example, having used computers since TRS-80, I'd say probably.
__________________
I don't know nothing, and I memorized it in school and got this here paper I'm proud of to show it.
Likes For Rollfast:
#40
Senior Member
Join Date: Nov 2015
Posts: 8,922
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 4717 Post(s)
Liked 1,882 Times
in
998 Posts
The guy that made the video is wanker. He knows what he’s talking about, but he’s marketing a product that he created, to help prevent an issue that isn’t really an issue.
#41
Zoom zoom zoom zoom bonk
Join Date: Sep 2006
Location: New Zealand
Posts: 4,624
Bikes: Giant Defy, Trek 1.7c, BMC GF02, Fuji Tahoe, Scott Sub 35, Kona Rove, Trek Verve+2
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 551 Post(s)
Liked 722 Times
in
366 Posts
I especially like how he totally glossed over the importance of getting the top bolt tension correct.
#42
What happened?
Join Date: Jun 2007
Location: Around here somewhere
Posts: 7,927
Bikes: 3 Rollfasts, 3 Schwinns, a Shelby and a Higgins Flightliner in a pear tree!
Mentioned: 57 Post(s)
Tagged: 1 Thread(s)
Quoted: 1835 Post(s)
Liked 292 Times
in
255 Posts
I just hope that's only his ID. Sounds a bit cruel to him.
__________________
I don't know nothing, and I memorized it in school and got this here paper I'm proud of to show it.
#44
Senior Member
Join Date: Aug 2019
Location: Québec, Canada
Posts: 2,112
Bikes: SL8 Pro, TCR beater
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 986 Post(s)
Liked 583 Times
in
438 Posts
Last edited by eduskator; 09-22-19 at 03:30 PM.
#45
Senior Member
Join Date: Mar 2010
Posts: 1,659
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 1247 Post(s)
Liked 1,323 Times
in
674 Posts
Regarding the need for a compression plug to support the steerer tube. I owned a Colnago C59 which used a wedge type headset which eliminated the need for a top cap to set the preload. Just mounted the stem a flush as possible and the set preload at the headset.
#46
bike whisperer
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,545
Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1526 Post(s)
Liked 718 Times
in
510 Posts
FWIW, none of my carbon steerers poke out of the stem, but I ensure my compression plugs are a good design and are set up properly, and the bottom bolt on my stems is tighter than the top. Seems prudent to remember we're dealing with fibre reinforced plastic...
Funny how this guy says that many manufacturer did not engineer well their factory compression plugs & finds flaws in them (IE, says that Giant should have opted for a straight plug instead). I mean, if the damn product was developed and engineered in a specific way (including shape), I'm confident it's pretty much doing what it should be doing.
That one's utter crap, and there are worse than that.
I guess the risk of your stem popping off your carbon steerer must be pretty minimal if Darwin has allowed these poxy units to continue to be a thing... I like to sail pretty close to the wind, but this is a risk I'm going to mitigate, albeit to less of an extent than the accepted wisdom.
__________________
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Last edited by Kimmo; 09-22-19 at 09:33 PM.
#47
climber has-been
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,101
Bikes: Scott Addict R1, Felt Z1
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3425 Post(s)
Liked 3,561 Times
in
1,790 Posts
There isn't. Stop perpetuating a myth.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse
Ride, Rest, Repeat. ROUVY: terrymorse
Likes For terrymorse:
#48
bike whisperer
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,545
Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1526 Post(s)
Liked 718 Times
in
510 Posts
Some are so bad they struggle to grip enough to preload the bearings, let alone support the steerer internally (the necessity of which is apparently a matter of controversy), others don't stand a chance of performing the latter despite managing the former, and the one pictured above manages to introduce a new degree of crapness by trying to be clever and integrating the top cap, which turns against the stem as you're preloading the headset, which is plain nasty, and makes it a fiddly hassle for no good reason. The rest of its design is equally nasty.
It's crap, and if you insist on disagreeing, I submit that you lack the discernment to perceive that.
__________________
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Last edited by Kimmo; 09-22-19 at 10:18 PM.
#49
climber has-been
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,101
Bikes: Scott Addict R1, Felt Z1
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3425 Post(s)
Liked 3,561 Times
in
1,790 Posts
I can read a drawing, and there appears to be nothing wrong with the design depicted in the drawing. It looks like so many other designs from so many other manufacturers.
Point to the place in the drawing that shows the claimed design flaw in this compression plug that prevents it from providing a bearing pre-load.
Point to the place in the drawing that shows the claimed design flaw in this compression plug that prevents it from providing a bearing pre-load.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse
Ride, Rest, Repeat. ROUVY: terrymorse
Last edited by terrymorse; 09-22-19 at 10:49 PM.
Likes For terrymorse:
#50
bike whisperer
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,545
Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1526 Post(s)
Liked 718 Times
in
510 Posts
I never said this plug in particular couldn't do that; I said it was crap in its own special way - if you can read a drawing you might be able to see the problem. Unlike plugs from other companies, the top cap is the tension bolt, which in practice, sucks.
Also, from memory, the tapers are a bad angle and it needs to be lubed (something I always do but is otherwise rare) to work at all, and the short length that bears on the inside of the steerer is badly placed; too low IIRC.
I'm reminded of a whole bunch of undercooked me-too internal cable routing in frames that I've come across, which only passed muster because you can't see it. The assumption that a big company employing qualified engineers will necessarily make parts that a bloke on the street couldn't find problems with, is false.
Whether compression plugs have one job that matters or two is a matter of debate. Whether some are absolute crap shouldn't be. I've even seen a rubber sandwich!
Also, from memory, the tapers are a bad angle and it needs to be lubed (something I always do but is otherwise rare) to work at all, and the short length that bears on the inside of the steerer is badly placed; too low IIRC.
I'm reminded of a whole bunch of undercooked me-too internal cable routing in frames that I've come across, which only passed muster because you can't see it. The assumption that a big company employing qualified engineers will necessarily make parts that a bloke on the street couldn't find problems with, is false.
Whether compression plugs have one job that matters or two is a matter of debate. Whether some are absolute crap shouldn't be. I've even seen a rubber sandwich!
__________________
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Last edited by Kimmo; 09-22-19 at 11:47 PM.