Tune stem, why spacer on top?

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

Post Reply
Canofale
Posts: 50
Joined: Sun Jan 17, 2016 7:33 pm
Location: UK North West

by Canofale

I'd like a Tune stem, product spec states a 5mm spacer must be used above. Why is this? I like to follow manufacturers instructions wherever possible but seeing as my stem is slammed it's not a possibility. Also Cannondale state not to use any spacers above the stem when using their forks, this I can understand due to depth of expander plug. Is anyone using a Tune stem without said spacer? Thanks.
2015 Caad10 Ultegra 7.1kg
2016 Giant TCR Advanced Pro 6.6kg

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

So the whole of the stem clamps onto the steerer.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

It's not so much the spacer as much as they want good contact with the steertube and enough room to be able to apply a preload when installing without bottoming out. Specifying a spacer generally allows that whereas sometimes the way the expander bolt works the steertube has to be cut lower if you want ta flush top cap. Cannondale's caps are designed to sit flush. Does your steertube extend to the top of the stem at least, providing good support for the stem. If not quite to the top, does it at least extend past the area where the top bolt of the stem clamps? That's the critical part. If it is below that or even the same, the top bolt can sometimes "squish" the top of the steer tube making it kind of like a cone, and even if it doesn't crack the steertube, the force and the resulting cone shape can tend to want to pull the stem up the steer tube, and then voila, sloppy interface with headset requiring constant adjustment. Use your judgement.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

Canofale
Posts: 50
Joined: Sun Jan 17, 2016 7:33 pm
Location: UK North West

by Canofale

My steerer tube is 2-3mm below top of stem as per cannondales instructions to allow room for preload. I don't understand why Tune specify a spacer whereas other manufacturers don't?
2015 Caad10 Ultegra 7.1kg
2016 Giant TCR Advanced Pro 6.6kg

User avatar
PSM
Posts: 1706
Joined: Tue Aug 28, 2012 2:45 pm
Location: Stockholm, The Arctic...

by PSM

Most cyclist in the pro peleton has at least 5 mm spacer a above the stem. I think most manufacturers recommend this

Some examples:

https://roadcyclinguk.com/gear/gear-new ... zL1jyUA.97

User avatar
PSM
Posts: 1706
Joined: Tue Aug 28, 2012 2:45 pm
Location: Stockholm, The Arctic...

by PSM

Image

User avatar
madcow
Shop Owner
Posts: 3740
Joined: Sun Feb 06, 2005 4:22 pm
Location: Tucson, Az.
Contact:

by madcow

Tune requires the spacer because of the style of stem. It's not a closed stem but instead uses more of a band across the top. That means to get the right amount of contact you need to have the steerer going completely through the stem whereas with other stems which are completely closed around the steerer you don't. However as was already pointed out, it's always a good idea to have some spacer on top of the stem as it reduces the chances of cracking the steerer tube.

You can see here if the steerer didn't reach the top of the stem the amount of contact between stem and steerer would be pretty minimal:
Image

User avatar
mythical
Posts: 1515
Joined: Fri Apr 04, 2008 2:49 am
Location: Europe
Contact:

by mythical

A spacer above the stem is mainly necessary for carbon steerers, which pretty much every respectable lightweight bike has these days. Manufacturers don't want to be responsible for potential steerer failures of their customers and all the damages that might result therefrom.
“I always find it amazing that a material can actually sell a product when it’s really the engineering that creates and dictates how well that material will behave or perform.” — Chuck Teixeira

User avatar
bikerjulio
Posts: 1900
Joined: Fri Dec 11, 2009 10:38 pm
Location: Welland, Ontario

by bikerjulio

I think @madcow's picture explains perfectly. If your steerer is cut 3mm below the top of the stem, then obviously a Tune stem is not for you. Cannondale's design obviously did not anticipate stems that were so cut away.

So, if you have a Cannondale type setup, then a stem with more clamping area is required. Like Ritchey.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

Depends how much your stem is slammed. An even shallow dustcover (that sits immediately on top of the head tube) than your existing one might get you a little more space.

Leaving spacers above the stem is not always the best idea - as already stated, it depends on the stem. Spacers above the stem always seem to take the damage when a bike topples over.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Canofale
Posts: 50
Joined: Sun Jan 17, 2016 7:33 pm
Location: UK North West

by Canofale

madcow wrote:Tune requires the spacer because of the style of stem. It's not a closed stem but instead uses more of a band across the top. That means to get the right amount of contact you need to have the steerer going completely through the stem whereas with other stems which are completely closed around the steerer you don't. However as was already pointed out, it's always a good idea to have some spacer on top of the stem as it reduces the chances of cracking the steerer tube.

You can see here if the steerer didn't reach the top of the stem the amount of contact between stem and steerer would be pretty minimal:
Image



Good explanation, I get it now, thanks.
2015 Caad10 Ultegra 7.1kg
2016 Giant TCR Advanced Pro 6.6kg

Post Reply