Number of spacers recommended

Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
Technical discussion, description and outright lies

Number of spacers recommended

Postby kimmie » Tue Apr 16, 2013 10:16 pm

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. :cry:
"Ride like the wind, Bullseye!"
kimmie
 
Posts: 554
Joined: Sun Apr 17, 2011 10:05 pm
Location: Melbourne, VIC

by BNA » Tue Apr 16, 2013 10:58 pm

BNA
 

Re: Number of spacers recommended

Postby twizzle » Tue Apr 16, 2013 10:58 pm

I raced an alloy Giant TCR for for ~2 years with 60mm of spacers under the stem on an alloy steerer. My wet commuter runs 4cm of spacers.

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...
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: Number of spacers recommended

Postby scirocco » Wed Apr 17, 2013 7:42 am

If it is any consolation, when manufacturers give maximum loadings etc they are very conservative. They have to be to avoid getting sued. So the "limit" of 4cm will be based on something like having a safety margin for a 130 kg gorilla trying to rip the bars off in a 1800W sprint. If that guy isn't you then you probably have an even larger safety factor. Even at 5cm.

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.
scirocco
 
Posts: 314
Joined: Thu Sep 29, 2011 7:34 pm

Re: Number of spacers recommended

Postby kimmie » Wed Apr 17, 2013 8:37 am

@twizzle: Thanks for sharing your experience. Mine is a Carbon steerer - will that makes it more fragile?
@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...
"Ride like the wind, Bullseye!"
kimmie
 
Posts: 554
Joined: Sun Apr 17, 2011 10:05 pm
Location: Melbourne, VIC

Re: Number of spacers recommended

Postby twizzle » Wed Apr 17, 2013 9:16 am

kimmie wrote:@twizzle: Thanks for sharing your experience. Mine is a Carbon steerer - will that makes it more fragile?


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*.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: Number of spacers recommended

Postby RonK » Wed Apr 17, 2013 10:12 am

twizzle wrote:I raced an alloy Giant TCR for for ~2 years with 60mm of spacers under the stem on an alloy steerer...

Hincapie's only lasted a couple of hours...
Image
Cycle touring blog and tour journals: whispering wheels...
User avatar
RonK
 
Posts: 5369
Joined: Mon Aug 24, 2009 2:08 pm
Location: Brisbane, Queensland

Re: Number of spacers recommended

Postby twizzle » Wed Apr 17, 2013 10:47 am

RonK wrote:Hincapie's only lasted a couple of hours...

Because Lance weakened the tube with a hacksaw after George called him fat.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: Number of spacers recommended

Postby jacks1071 » Wed Apr 17, 2013 11:24 am

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. :cry:


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

Image

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.
Our Website is: http://www.pro-liteoz.com Find us on Facebook by searching for "Pro-Lite Australia"
User avatar
jacks1071
 
Posts: 2960
Joined: Thu Aug 20, 2009 9:47 pm
Location: Mackay, QLD

Re: Number of spacers recommended

Postby RonK » Wed Apr 17, 2013 12:26 pm

twizzle wrote:
RonK wrote:Hincapie's only lasted a couple of hours...

Because Lance weakened the tube with a hacksaw after George called him fat.

He called him a drug cheat too - I wonder what Lance will do to get even for that... :lol: :lol: :lol:
Cycle touring blog and tour journals: whispering wheels...
User avatar
RonK
 
Posts: 5369
Joined: Mon Aug 24, 2009 2:08 pm
Location: Brisbane, Queensland

Re: Number of spacers recommended

Postby twizzle » Wed Apr 17, 2013 1:00 pm

RonK wrote:
twizzle wrote:
RonK wrote:Hincapie's only lasted a couple of hours...

Because Lance weakened the tube with a hacksaw after George called him fat.

He called him a drug cheat too - I wonder what Lance will do to get even for that... :lol: :lol: :lol:

Everyone called him a drug cheat. But no-one gets away with calling him fat.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: Number of spacers recommended

Postby warthog1 » Sat Apr 20, 2013 3:20 pm

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

Image

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.


+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.
User avatar
warthog1
 
Posts: 2885
Joined: Wed Jul 25, 2012 4:40 pm

Re: Number of spacers recommended

Postby TDC » Sat Apr 20, 2013 6:36 pm

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.


Not to forget, if you flip up the stem, you have to put on racks and panniers. :lol:
TDC
 
Posts: 568
Joined: Fri Jun 10, 2011 8:37 pm
Location: Adelaide

Re: Number of spacers recommended

Postby Dave R32 » Tue Apr 23, 2013 1:53 pm

TDC wrote:
Not to forget, if you flip up the stem, you have to put on racks and panniers. :lol:


And a beard.......your second bike will be a recumbent. :-)

Cheers
Dave.
Avanti Vivace = Sold | Trek Madone = Cracked | '12 Caad10 = Sold | Pinarello SDG3K = Sold | '14 Caad10 & Bianchi Pista
User avatar
Dave R32
 
Posts: 771
Joined: Tue Nov 18, 2008 7:12 pm
Location: North Lakes - Brisbane

Re: Number of spacers recommended

Postby jacks1071 » Wed Apr 24, 2013 9:09 pm

Our Website is: http://www.pro-liteoz.com Find us on Facebook by searching for "Pro-Lite Australia"
User avatar
jacks1071
 
Posts: 2960
Joined: Thu Aug 20, 2009 9:47 pm
Location: Mackay, QLD

Re: Number of spacers recommended

Postby toolonglegs » Thu Apr 25, 2013 12:45 am

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... ;-)
Image
User avatar
toolonglegs
 
Posts: 14405
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: Number of spacers recommended

Postby jacks1071 » Thu Apr 25, 2013 10:51 pm

toolonglegs 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... ;-)


I've seen guys do that, it goes bad when they ride out to racing and realise the headset is loose :-)

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?
Our Website is: http://www.pro-liteoz.com Find us on Facebook by searching for "Pro-Lite Australia"
User avatar
jacks1071
 
Posts: 2960
Joined: Thu Aug 20, 2009 9:47 pm
Location: Mackay, QLD


Return to The Shed

Who is online

Users browsing this forum: Google [Bot], Mark7.4FX, Nate



Popular Bike Shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Ebay Ebay AU

“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter

> FREE BNA Stickers
> BNA Cycling Kit