Replacement 80mm Stem

[PhilsRoubaix]

Hi
This is my first post as I am new to road cycling & have purchased a second hand Specialized Roubaix Comp carbon cycle.
The current handlebar stem is 100mm long but I need to replace it with an 80mm stem (I’m a little chap so need to shorten the reach)
I want to buy the correct stem & getting somewhat confused with the many stems out there. I am more than happy to buy a good second hand stem - great to recycle.
My bike is a Roubaix Comp 2010.
Any advice as to what to buy would be appreciated.
Thanks.

 

[wafter]

Most important factors are stem diameter (I'd expect 31.8mm) and bar diameter (can't remember what the modern standard is tbh) - so you'll want to measure both. Most stems have a 7 degree angle but you might want to check this too.

Beyond this they're all much of a muchness; at least at the lower end of the market where I suspect you'll be shopping. Most are Chinese-source alloy from the same few manufacturers and re-branded. Within these limits really anything will do as long as it's decent quality and structurally sound.

There's plenty available used, while if you want to buy new it seems that "Uno" branded stems are very similar to a lot of OEM offerings

 

[Cycleops]

You also need to decide what angle you want on it. Some flip them to get a further adjustment:


View: https://youtube.com/shorts/UHdQnXLm09s?si=qxocJVgtPzE0LWlS

 

[bikingdad90]

Could you post a picture of the bike? You can often reduce the reach to the hoods by relocating the shifters further up the bars which is free to do.

 

[youngoldbloke]

The other thing to consider is the stem stack height (where it clamps around the steerer tube). Try to match it to the existing stem otherwise you may have to play around with the spacers.

 

[wafter]

Also, if the steerer tube on the bike is composite you want a stem with a "full" clamping surface that goes around the tube; rather than one that has a hole in the front where it intersects the main body of the stem. Edges (especially if sharp) in the area can cause stress raisers on composite steerers that promote failure..

 

[Cycleops]

So all in all a lot to consider @PhilsRoubaix You might consider a bike fit to maximise your comfort. Not cheap but rules out all the trial and error. Your local bike shop might offer this service.

 

[PhilsRoubaix]

Also, if the steerer tube on the bike is composite you want a stem with a "full" clamping surface that goes around the tube; rather than one that has a hole in the front where it intersects the main body of the stem. Edges (especially if sharp) in the area can cause stress raisers on composite steerers that promote failure..

Excellent advice from you all. Just I thought, it’s the finer details which can be easily overlooked. So I have purchased for £5 each both an 80mm & 90mm stem. Fitted both & the 80mm flipped up is perfect with no twitchy steering. What a difference. However, it’s a standard stem without the insert (the original Specialized has an insert as the bike is carbon with a composite steerer tube - just as you said). I have looked on line for a second hand stem with insert, but can’t find one at 80mm😕 Here’s the question - if I leave the standard one on but tighten it to say 3Nm, will it be OK? Do I really need to spend £90 on a new S Works Specialised stem with the insert? Or are there any other compatible stems with inserts?

 

[wafter]

Excellent advice from you all. Just I thought, it’s the finer details which can be easily overlooked. So I have purchased for £5 each both an 80mm & 90mm stem. Fitted both & the 80mm flipped up is perfect with no twitchy steering. What a difference. However, it’s a standard stem without the insert (the original Specialized has an insert as the bike is carbon with a composite steerer tube - just as you said). I have looked on line for a second hand stem with insert, but can’t find one at 80mm😕 Here’s the question - if I leave the standard one on but tighten it to say 3Nm, will it be OK? Do I really need to spend £90 on a new S Works Specialised stem with the insert? Or are there any other compatible stems with inserts?

Good work

I think there are several things at play here. I'm not familiar with that specific Specialized stem / the insert, but it would figure that they've taken some steps to mitigate the dangers associated with composite steerers.

I'd be very wary of under-torquing the clamp; I can see where you're coming from but equally if it's too loose you run the risk of it twisting under load / if you hit a bump; the potential consequences of which don't bear thinking about! I do generally go easy on tightening torques, but only usually go as low as 10 or 20% below the stated figure... for what that's worth. You could potentially apply some "carbon grip paste" which is basically abrasive paste that's intended to stop parts moving relative to each other, but I'm a bit wary of this too tbh.

If you do proceed with the one of the stems you have, I'd be inclined to give them a really good once-over at their contact faces / edges, de-burring as appropriate. Might be worth removing it after some miles and checking for damage / witness marks on the steerer tube too.

Tbh really we're into murky waters now; outside the bounds of my generalised advice.. really sounds like a question for someone more experienced with those products / the brand themselves.. although I suspect they'd just use it as an excuse to sell you an expensive stem or whole new bike..

 

[PhilsRoubaix]

Thanks again for the advice.
As you recommend, I have written to my local Specialized store to ensure I see which stem / stems are suitable for my bike. Taking the advice above, I am inclined to avoid a ‘standard’ stem as there is the real risk of pressure points on the carbon steerer tube which can lead to delamination - too expensive mistake in my view.
Sincere thanks again to you all & a happy new year pushing those pedals!