Having just got back from a ride with a very slightly off-centre stem that bothered me more than it should I’m wondering why steerer tubes aren’t splined. They wouldn’t need the full treatment, just a single groove up the front would do it. The dimensions could be standardised across brands, it could be so shallow that it would have no impact on strength, and it would be completely compatible with existing non-splined stems. The standard could even be based around a matching a shallow groove in the stem with a small diameter rod or bar used while fitting to align the stem with the steerer, as this would then mean that all stems were compatible with all steerers.

Or am I being stupid…?

I guess you might actually want the stem to twist in a crash.

dimensions could be standardised across brands

🙄

what he ^^^ said plus it’s simple enough to set up properly as it is

edit: not him, the guy above him

The dimensions could be standardised across brands

😀

stress raisers, twist in a crash is good, more expensive to make, etc etc.

There are X standards for steerers now.

Someone will come up with a clever, new, better standard to replace all those standards.

There are now X+1 standards. 😉

mrmo has it.

Because there is no reason to have it splined. Most people carry allenkeys so could easily solve the off centre stem….

A printed line on the tube and a dot on the stem would be better, but not really necessary. I’ve heard some folk intentionally rotate the stem a degree or two to help with a shoulder problem.

And besides, if your route involves lots of turning right, for example a clockwise route at a trail centre, some people need to run the steerer slightly off-centre to allow for this.

martin wins the internet for today 😀

More expensive to make as you’d spend more time getting the steerer aligned perfectly

I think motorbikes are splined.
A spinning stem is my nightmare. Just how tight do you go?
You can snap bolts or have steerer failure if too tight.
Too loose and you lose your teeth.
Splined would sort that.

Do people really rely on stems twisting in a crash? Why is that good? And if the rod/bar were removable this wouldn’t stop that anyway – it would just be used for fitting leaving it free to rotate in a crash once fitted.

Perhaps it’s just me but I find it very hard to get stems aligned properly – they’re too short to be able to eyeball accurately against something with the characteristics of a tyre. It’s not about the allen keys, it’s about the visual characteristics of the parts involved.

I take the point about standardisation asterix, but it seems to work for most other parts on a bike so it is certainly feasible. And it would provide a small extra benefit (or at least a claimed benefit) that manufacturers could use to market their wares, so there’s an incentive for them, assuming it’s a cheap thing to do

I’m well aware this this is not a problem of major global importance. It just seems to me that there’s value in having something that is designed to be aligned properly rather than relying on trial and error to get it right.

It would. It would also weigh more or be less robust and be more expensive. Given that almost everyone has no issue with the current solution, what about splined is actually better about it?

Mind you, come to think of it, you could probably apply that to a few bike ‘innovations’ 🙂

my double-groove-with-removable-fitting-rod approach would actually weigh infinitesimally less, and I can’t see how it would have a material effect on strength…

If you have problems lining it up by eye, use a broom handle or similar parallel to the bars. You can spot it a mile off then.

Or just do your first ride with an Allen key in your pocket 😉

I take the point about standardisation asterix, but it seems to work for most other parts on a bike so it is certainly feasible.

sorry my post was a bit harsh/tounge in cheek – I was just reflecting on the recent de-standardisation of wheels, tyre sizes etc

I think motorbikes are splined.

Some might be but I don’t think most are, at least. Triple crown forks, see?
I had a bike with a slightly skewiff front end. All sorted as part of a service.

my double-groove-with-removable-fitting-rod approach would actually weigh infinitesimally less, and I can’t see how it would have a material effect on strength

Still promotes a stress point in steerer & stem & mean fork manufs have to make sure steerer is fitted dead centre in crown rather than just pressed into place any old how

Non-aligned stems annoy me too, and aligning to the tyre is generally IME not very successful… my setup method is to look down at such an angle that the middle of the bars line up with the front of the fork dropouts, you can then quickly see if the bars are straight or not. Works for me… Your experience may vary!

I’ve heard some folk intentionally rotate the stem a degree or two to help with a shoulder problem.

<Waves hello>

Oh well, worth asking – I’m clearly in an anally retentive minority 🙂

PS hello PeterPoddy. We still make your biscuits from the recipe you posted several years ago…yum yum

I use a method similar to nre, but eye the fork brace with the stem faceplate or bolts.

There are a few folding bike designs that have splined steerers or similar – the big problem is that unless your manufacturing tolerances are very, very tight, there’s too much slop in the spline to allow spot-on alignment anyway. Or, worse, your stem doesn’t quite match your steerer by a fraction of a mm and you can’t get your bars straight.

The bar/fork alignment technique sounds good – I’ll give that a go – thanks!

Another vote for bar / fork allignment. I’ve broken my collarbones four times now so both arms extend to a different extent than the OEM. Even when I have the bars straight I think my bars aren’t!

Chris

On top of everything mentioned just think of all the increased warranty claims for CSUs that have not been pressed in quite right.

In the detailed working drawing below, you will see that alignment is simply a case of eyeing the top circles of the fork crowns through with the back surface of your bars. Simple.

Another reason against is stems that become quite sticky and hard to remove. Always come loose with a bit of wobbling about which a locator would not allow. 🙂

A groove would also weaken the steerer tube.

you have the practicality of making it central. on steerer and stem. from two different manufacturers.

you have tolerances on both, imagine being unlucky and they stack up and then you can never get it straight.

imagine hunting through the shop for a stem that’s a bit clockwise because your steerer’s a bit anti CW.

it’s be 10 times worse than your ride today.

A splined steerer would also deny us the fun of seeing BSOs in supermarkets with the forks fitted backwards. 🙂

^ nah, they’d just have very short effective top tubes 😉

I’m sorry, what problem are we trying to solve?

The reason why it’s not going to ever happen, is that it doesn’t solve a problem.

Misaligned bars are not a problem, they are lined up by yourself when fitting a stem.

Regardless of how simple it makes it, there’s just no problem to solve. It’s the reason why so many *good* ideas fail, trying to solve a problem that doesn’t exist.

I can’t believe no one has brought up seatposts in this thread.

What about all the poor misaligned saddles out there.
For what ever reason you would purposely want you saddle twisted, please keep to your self. 😀

rickon – Member

The reason why it’s not going to ever happen, is that it doesn’t solve a problem.

15mm axles.

6/7/8/9/10/11 speed.

press-fit BB’s.

post-mount brakes.

i could go on.

What about all the poor misaligned saddles out there.
For what ever reason you would purposely want you saddle twisted, please keep to your self.

What about the people with un-even hanging… err, fruit?

Those who predominantly dress to the right may wish to have the saddle nose pointed slightly to the left to leave ample room for said appendage(s).

Don’t Giant have a D shaped seat post on some models?

the current solution works fine, unless you have OCD

most current stems using dual clamping bolts have a setting torque of 5nm

this is more than enough to hold the stem secure on the fork steerer during normal use (or even quite extreme use i.e. freeride, dirt jump and downhill!)

but will also prevent damage to the stem or fork steerer if you have a big “off” as the design will allow the energy involved to overcome the bolt torque and rotate the stem on the steerer, rather than snap it!

15mm axles.

6/7/8/9/10/11 speed.

press-fit BB’s.

post-mount brakes.

Yes, but all those things have tangible benefits – even if you disagree with them being the right standard or not.

Plus they come with a lot of stuff for the market to sell, shifters, chains, cassettes, rings, mechs…. calipers, mounts… BBs, whole new frames.

Splined forks mean a new stem.

Plus I wonder how much that would add to the cost, when it’s not just a tube pressed into a frame?