Number of spacers recommended
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Number of spacers recommended
Postby kimmie » Tue Apr 16, 2013 10:16 pm
A n00b question... I understand that 40mm is the 'limit' for spacers under the stem, but is there any 'limitation' (or maximum height) for the spacers on top of the stem? My current bike has 40mm under and 20mm on top. Is that ok?
Secondly, how 'dangerous' it is to have 50mm spacers under my stem? My bike fit is best for 50mm, but I read that the recommended max stack is 40mm to avoid 'failure'.
I understand there are a lot of discussion about this on the net, but I would love to hear 'first hand' from you guys here in my trusted forum, rather from somewhere else, so please don't ask me to google.
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Re: Number of spacers recommended
Postby twizzle » Tue Apr 16, 2013 10:58 pm
But I also have two Ribble frames, one 62cm, one 64cm, with TT of 58cm and 59cm, so not many spacers anymore.
Sent from my iThingy...
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Re: Number of spacers recommended
Postby scirocco » Wed Apr 17, 2013 7:42 am
If you have a modern carbon steerer tube with the 2mm thick tube then it will probably survive a nuclear explosion. When I cut my carbon steerer down I tried running over the offcut with my car. It squished it a bit out of shape but it did not crack, tear or delaminate.
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Re: Number of spacers recommended
Postby kimmie » Wed Apr 17, 2013 8:37 am
@scirocco: LOL. I love your analogy. I am 178cm/77kg rider and I definitely don't have 1800W power... Well, my bike-fit was actually 6cm according to my LBS, but I try to compromise it a little bit by lowering the stem with 5cm spacers... Thanks for sharing your experiment with the carbon tube too. Really helpful.
So the stack on top of stem is irrelevant? It will not affect the strength at all? I mean with the bolt pressure, etc...
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Re: Number of spacers recommended
Postby twizzle » Wed Apr 17, 2013 9:16 am
No -alloy WILL fail from fatigue at some point in time. Carbon, when free of manufacturing defects, won't fatigue... well, that's what people in the industry *think*.kimmie wrote:@twizzle: Thanks for sharing your experience. Mine is a Carbon steerer - will that makes it more fragile?
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Re: Number of spacers recommended
Postby RonK » Wed Apr 17, 2013 10:12 am
Hincapie's only lasted a couple of hours...twizzle wrote:I raced an alloy Giant TCR for for ~2 years with 60mm of spacers under the stem on an alloy steerer...
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Re: Number of spacers recommended
Postby twizzle » Wed Apr 17, 2013 10:47 am
Because Lance weakened the tube with a hacksaw after George called him fat.RonK wrote:Hincapie's only lasted a couple of hours...
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Re: Number of spacers recommended
Postby jacks1071 » Wed Apr 17, 2013 11:24 am
I'm going to assume we are talking about a carbon steerer here?kimmie wrote:Hi all,
A n00b question... I understand that 40mm is the 'limit' for spacers under the stem, but is there any 'limitation' (or maximum height) for the spacers on top of the stem? My current bike has 40mm under and 20mm on top. Is that ok?
Secondly, how 'dangerous' it is to have 50mm spacers under my stem? My bike fit is best for 50mm, but I read that the recommended max stack is 40mm to avoid 'failure'.
I understand there are a lot of discussion about this on the net, but I would love to hear 'first hand' from you guys here in my trusted forum, rather from somewhere else, so please don't ask me to google.
There is no limit to the spacers on top of the stem however it is beneficial to have the stem clamp the area that is supported by the spreader bolt / wedge. This is because that will help prevent crush damage.
When you put too many spacers on top of the stem, you need an extra long spreader bolt / wedge if you want to support the stem clamping area.
I had some of these made up extra long for just such a purpose, the long version is 52mm which should cover you nicely for 20mm of spacers on top of the stem.
http://www.pro-liteoz.com/store/index.p ... oductId=41" onclick="window.open(this.href);return false;
I would not run more than 40mm of spacers beneath the stem on a carbon steerer.
If you need more than 40mm either flip the stem up, or get a stem with more angle, or change the fork to one with an alloy steerer.
Safety first when it comes to steerers, if you break a steerer you will crash and its almost always head first into the bitumen.
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Re: Number of spacers recommended
Postby RonK » Wed Apr 17, 2013 12:26 pm
He called him a drug cheat too - I wonder what Lance will do to get even for that...twizzle wrote:Because Lance weakened the tube with a hacksaw after George called him fat.RonK wrote:Hincapie's only lasted a couple of hours...
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Re: Number of spacers recommended
Postby twizzle » Wed Apr 17, 2013 1:00 pm
Everyone called him a drug cheat. But no-one gets away with calling him fat.RonK wrote:He called him a drug cheat too - I wonder what Lance will do to get even for that...twizzle wrote:Because Lance weakened the tube with a hacksaw after George called him fat.RonK wrote:Hincapie's only lasted a couple of hours...
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Re: Number of spacers recommended
Postby warthog1 » Sat Apr 20, 2013 3:20 pm
+1 to this post really good advice. Make sure the compression nut/spreader is located inside the steerer where the handlebar stem applies its clamping force.jacks1071 wrote:
I'm going to assume we are talking about a carbon steerer here?
There is no limit to the spacers on top of the stem however it is beneficial to have the stem clamp the area that is supported by the spreader bolt / wedge. This is because that will help prevent crush damage.
When you put too many spacers on top of the stem, you need an extra long spreader bolt / wedge if you want to support the stem clamping area.
I had some of these made up extra long for just such a purpose, the long version is 52mm which should cover you nicely for 20mm of spacers on top of the stem.
http://www.pro-liteoz.com/store/index.p ... oductId=41" onclick="window.open(this.href);return false;
I would not run more than 40mm of spacers beneath the stem on a carbon steerer.
If you need more than 40mm either flip the stem up, or get a stem with more angle, or change the fork to one with an alloy steerer.
Safety first when it comes to steerers, if you break a steerer you will crash and its almost always head first into the bitumen.
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Re: Number of spacers recommended
Postby TDC » Sat Apr 20, 2013 6:36 pm
Not to forget, if you flip up the stem, you have to put on racks and panniers.jacks1071 wrote:
I would not run more than 40mm of spacers beneath the stem on a carbon steerer.
If you need more than 40mm either flip the stem up, or get a stem with more angle, or change the fork to one with an alloy steerer.
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Re: Number of spacers recommended
Postby Dave R32 » Tue Apr 23, 2013 1:53 pm
And a beard.......your second bike will be a recumbent.TDC wrote:
Not to forget, if you flip up the stem, you have to put on racks and panniers.
Cheers
Dave.
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Re: Number of spacers recommended
Postby jacks1071 » Wed Apr 24, 2013 9:09 pm
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Re: Number of spacers recommended
Postby toolonglegs » Thu Apr 25, 2013 12:45 am
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Re: Number of spacers recommended
Postby jacks1071 » Thu Apr 25, 2013 10:51 pm
I've seen guys do that, it goes bad when they ride out to racing and realise the headset is loosetoolonglegs wrote:Shouldn't really tell you how I run my tt bike lol... Slammed adjustable stem, use expandable adjuster and spacers to set the bearing tension... But I need them for another bike, so once the stem is done up I take them all off...
To be fair, you probably don't stress the steerer on the TT bike so much as you arn't swinging off it like you would a road bike and I'd imagine the KMS on it would be pretty limited compared to the roadie?
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