Serious question. How do you guys work out how many are needed? Most stock bikes seem to come with around 10-15mm of spacers. Do people really notice adding removing any when on the bike?

You add/remove them to raise / lower the bars.

Go out and try it. You may find lowering the bars puts more weight on the front which can help with front grip when cornering. Or raise them to reduce the weight you put through your arms.

Its subtle, but you will notice it at the extreme, which is when you need all the help you can get.

We are all different, so what suits you and your riding wont be the same as the rest of us.

For me I felt a difference.

Experiment and figure it out.

Stem spacers, you say?

Work it out from desired stack and reach. More spacers increases stack and reduces reach (how much depends on head angle.)

Do people really notice adding removing any when on the bike?

Some people are more sensitive to this sort of thing than others. On a road bike 10mm is huge. I’d definitely notice it on a mtb too.

Definitely notice it myself. With my ageing back it seems that every 5 years requires a lift of 10mm.

I moved my road bike stem up a couple of spacers (less than 1cm) for a longer, less speed orientated, ride and def felt the difference, especially out of the saddle.

<cough> sure it suits him fine, which is what matters I guess. But still even I balked at this in the classifieds recently…

I think I have 30mm of spacers under the stem on my gravel bike. Tried less, got lower back ache, glad I didn’t follow the fashionistas and slam my stem.

On the MTBs I generally cut a steerer to length plus 20mm, and fit 10mm under and 10 over the stem initially before possibly moving a few spacers about… Seems to work fine.

I hope that ^^^^^isn’t using a carbon steerer…..

That ^^^ is bizarre. Very long legs and very short arms?

just enough to stop the shifter smacking the top tube.

Haha, cheers. I have cut mine with 5mm under the stem and 15 above to give me the chance to play about with height. I have put 10 and 15 under the stem, and with only an initial pedal up and down the road I didn’t notice any difference, so went back to the 5mm. Hence the question of people really noticing.

glad I didn’t follow the fashionistas and slam my stem brought a bike that fits.

😉

It’s all down to reach and stack though isn’t it. Some bike manufacturers want to use the same head tube component for multiple frame sizes. The result is that different nominal ‘sizes’ of bike will have the same stack for different reach measurements. Simply requires the use of a few spacers to bring the bars up to the ‘correct’ height 😉

So, added another 10mm spacer last night (total of 15mm spacers) … I actually *think* it felt different, then removed it and replaced it with a 5mm (total of 5mm spacer), and *think* it felt worse. Now I’m thinking this is all in my head. There’s no way a single 5mm spacer can make that kind of difference 😯

I’m very pea and princess about this sort of thing. I have my bike set-up dimensions written down so I can set up any bike just right. A 5mm spacer in the wrong place is definitely noticeable.

But very roughly – I like it as low as possible at the front to get lots of weight on the front wheel, but not so low that I get a sore back. So start low, then add spacers under the stem until you are comfy. Do a fettling ride where you try it all out on the trail and swap them about there and then.

Thanks @Yak – I’m really struggling on how it *should* feel. 5mm and I can definitely feel like I have weight forward with more pressure on my hands. 15mm and I feel much more balanced with equal weight between hands and saddle.

This is all with saddle at full height.