Stiffer stem = more watts sprinting?

Take your stem off and stick it in a vice, then try bending it

Depends on the stem. As above, I had a very visibly flexy stem on my bike for ages. 2-3cm of flex on the ends of the bars when I twisted them, and it was visibly the stem. It didn’t break though.

Just buy it and report back when you score all those bridge crossing KOMs…

Take your stem off and stick it in a vice, then try bending it

I still ride a bike with a quill stem and I can visibly see it flex when pulling on the bars (I am probably putting out 3000W from my arms though)

Realise we are not really talking about quill stems but they flex and it makes no difference to my speed as my legs are providing that.

I had a very visibly flexy stem on my bike for ages. 2-3cm of flex on the ends of the bars when I twisted them, and it was visibly the stem. It didn’t break though.

molgrips

Depends on the stem. As above, I had a very visibly flexy stem on my bike for ages. 2-3cm of flex on the ends of the bars when I twisted them, and it was visibly the stem. It didn’t break though.

2-3cm of movement at the end of the bars, caused solely by flex in the stem!?
How wide were the bars? And how stiff were they?! I would expect the force required to flex a stem that much would also cause noticeable bending in the bar.
No way I would be riding that!

Are you sure you don’t mean 2-3mm?

……makes mental note to try & bend bar/stem combo as much as possible when next in the garage!

And yet so many people race without injury!

Yes so few crashes in Cat 5..

BTW Strava is not a race, it’s a competition, unless you’re cheating and getting KOMs in a race :p

I thought Strava was a training aid/way to track rides?

I thought Strava was a training aid/way to track rides?

2-3cm of movement at the end of the bars, caused solely by flex in the stem!?
How wide were the bars? And how stiff were they?! I would expect the force required to flex a stem that much would also cause noticeable bending in the bar.

The stem was a Syntace F99 105mm and the bars were Easton Monkeylite SL carbon low-risers I think 620mm. The bars might’ve flexed a bit but you could see the stem twisting. It was a bit unsettling when I discovered it, but it wasn’t obvious straight away as one generally has both hands on the bars during high load. Rode the bike for years without issue, and I’m not light. It didn’t bend up and down, it just twisted. It was very much a ‘holy shit’ moment when I discovered it.

Yes so few crashes in Cat 5..

BTW Strava is not a race, it’s a competition, unless you’re cheating and getting KOMs in a race :p

Not sure what cat 5 is, but I’ve raced cat 3 & 4 for about 5 years and never crashed. I also didn’t win either, maybe more crashing = more wins.

Whatever tickles your pickle regarding the OP but I’d focus on other things way before I start worrying about stem flex..

Mate if you need to measure the size of your penis I think a ruler is cheaper and more accurate?

What have your results been like so far?
He got a KOM on a bridge over a German river 🙂

Shut the Front Door, surely not THE bridge over THAT river? Man, if only they all knew!!!!

Surely if you’re bending stems, there’s going to be more squish in your tyres, long before the stem bends?

Whatever tickles your pickle regarding the OP but I’d focus on other things way before I start worrying about stem flex..

Think we got to the conclusion that unless you have flex-free bars stem flex is likely not going to be a factor and even if you do have nobody has measured the effect on peak wattz – modern stems are for most part pretty non-flexy.

Shut the Front Door, surely not THE bridge over THAT river? Man, if only they all knew!!!!

It’s the spree, very famous river around these parts :p

if you do have nobody has measured the effect on peak wattz –

That’ll be because the number of people who care about their 1s power is infitesimally small

If you want to feel stem flex go and try an old 1″ steerer solid aluminium quill stem – feels downright scary back to back with a modern bike!

I’d also be asking how accurate is the actual power measurement over 1 second?There is an angular velocity and averaging in that calculation and you are also accelerating.

I regularly get significantly different strava times on the same ride when I test 2 devices at the same time.  I think a change of stem is the least of your issues if completing strava is the aim.

I regularly get significantly different strava times on the same ride when I test 2 devices at the same time.

And that is even more apparent when dealing with 30 second segments which are dodgy enough to start with.

I think BMX racing would be the ideal sport in this case as the power really is the first few seconds then once in the lead just keep it. May have to like crashing even more than in a road race though.

the only watts lost due to stem bending would have to be disappated through heat. Even if it is flexing (which I doubt) – if its not getting warm (which it isn’t) then its a non-issue – any power not going to the wheels through flex is just being returned when the rider switches pulling to pushing on that side of the bar. there’s no damping circuits in play and metal as a spring is a remakably efficient thing