theworldisgray

I just got my caad 10. and i have a question about cutting my steerer tube and if i should
1. Leave a 5mm spacer on top of the stem so that i have 2mm of steerer tube above. or if i should
2. Do like Cannondale's manual says and cut the steerer tube to 2-3mm below the stem.
I would think the manufacture knows best and would rather follow the manual. but all the carbon steeres i have used before have wanted min of 5mm spacer above. thanks in advance for any inputs

rms13

I'm pretty sure Cannondale knows their products. There are reasons behind their recommendations and it's explained in the manual. Measure twice, cut once

milkbaby

I believe the reason behind Cannondale's instructions are because they want the compression plug supporting the steerer in the area where the stem is clamped. I'm guessing the design of the compression plug they use makes it such that more of the steerer under the stem clamping area is supported when no spacer is used above the stem.

theworldisgray

the manual shows a picture of the plug supporting the bottom if no spacers so maybe supporting the bottom is the most important? would it be ok to leave some above for a ride or two to dial in fit?

dvdslw

Yes, make sure you like the new position before you cut. Just do your best to avoid sharp impacts to the front wheel like jumping curbs, gutters, pot holes, etc... during your test period.

FIVE ONE SIX

i would personally cut as little of the steerer tube off as possible,within reason of course, cause there's no integrity difference whether you have spacers on top of the stem or not. also, having a longer steerer will come into play when you decide to sell the bike later on, cause the next owner is going to want some flexibility too...

i'm not saying you shouldn't slam the stem if you want to, i'm just saying it's better to have more of something you may not need than not have enough of something that you may decide you need later on...

rpenmanparker 

I strongly disagree with what you posted. The bike has to fit the current owner, not the imaginary next one. Also, leaving spacers above the stem when the design of the steerer and expansion plug do not provide for that is simply wrong.

OP, start by leaving about 2 cm more than you think you need and putting the corresponding spacers above the stem. Test it carefully for as long as need to, then cut the steerer to the length that gives the stem at the exact position you prefer with no spacers above it.

rpenmanparker 

That is the sensible explanation.

rms13

Except thats not what Cannondale recommends. Milkbaby's explanation of why your not supposed to leave spacers above the stem is correct. Probably not a big deal for a few weeks while OP dials it in but over the long haul I would listen to manufacturers recommendation

FIVE ONE SIX

all top caps are not the same, and Cannondale uses a pretty long top cap. so you can usually get away with a 5mm or even a 10mm spacer over it and it will be fine, as long as everything is torqued down correctly. not to mention that the top of steerer is it's weakest point for compression cracks, and that will always be protected with that top cap. usually the only time a carbon steerer cracks is from the top down when people decide to not use a compression plug and use a stem cap and bolt it down, and over tighten the stem bolts, but hey the OP can do whatever he wants...

rms13

He can do what he wants. If he puts spacers above the stem using Cannondale's compression plug then the bottom of the stem will be clamped below the compression plug which is designed to reinforce the steerer tube. There is more stress below the stem then above it due to leverage and then you add high leverage to the part of the steerer that is hollow and that can wear it down over time and cause failure. But with the ammount of carbon steerers that have actually failed on bikes compared to the ammount that haven't failed, odds are OP won't have any problems regardless of what he chooses unless he crashes the bike or has some other hard impact

pacalolo

The plug on my Synapse has enough vertical adjustment that I have no problem with a 5mm spacer above the stem, and the plug is perfectly aligned with the stem's clamping area around the steerer. I don't think I could adjust it to 15 or 20mm, but 5mm is practically nothing.

FIVE ONE SIX

don't get me wrong, i'm not saying that he should slam it and put 20mm of spacers above the stem, but the OP only wanted to put one 5mm spacer above the stem. it's just one of those things you can't take back once you do it, like i said i would rather have more of something i don't really need now than not enough of something i may need later on, and 5mm is so little i HIGHLY doubt that will ruin the integrity of the steerer at all. to each their own though...