Hi Lee, given that I strive for the lightest possible touch on the bars, how is important is stem stiffness?
My bike is used for racing XC, and the stem, which I think was really designed for a road bike, is 90mm.
Christopher (a skills client in Marin)
You raise an interesting question. Thoughts:
You’re right that your default setting should be light hands, heavy feet. Your hands should be neutral unless you’re pushing or pulling for some specific reason.
I’m not sure how stiff a stem has to be. I mean, do you pull and push so hard you feel your stem flexing? I doubt it. Besides, some flex absorbs impacts and helps your bike track on rough terrain.
A stiffer bar/stem system might give you a more connected feel. This could be useful for BMX/4X/pump track, or if you’re a powerful rider with an aggressive riding style. However, most riders are pretty timid, and XC racing is more about smoothness then full-on braaap.
Say your stem is very flexy. When I was in NorCal for Sea Otter, I did an shockingly aggressive ride with the Specialized crew. The trails were fast, rough and very DH. Pro gravity racer Christopher Herndon was given a pre-production carbon Stumpjumper 29er for the adventure. At the top of the first descent, he was like, “Wow, these bars are flexy.” He was straddling his bike and twisting the bar/stem assembly up and down an inch on each side. Was this setup flexy? Yes. Did he absolutely crush the descents? Yes. Did he crush the climbs too? Yes. This bike was way flexier than Chris’ usual setup, but it worked fine.
Strength is important. While I don’t see you breaking a stem with your bare hands, you need it to withstand all reasonable impacts. I assume any stem from a reputable maker will meet that standard. Exception: I once pulled the faceplace bolts out an Easton magnesium stem — mid race, mid gnar. The bars flew right off. I had such a concussion I screwed the bolts back in, dove back into the rock garden and BAM!!! lost the bars again. Ugly.
To sum it up: Some flex is OK, and maybe even good. As long as the stem is strong enough to handle impacts, which is should be, you’ll be fine.
When in doubt, ask the stem maker.
Braaap! (with a light touch)
Know more. Have more fun!
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