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Shimano PRO Vibe Sprint Mark Cavendish Star Series Road Bicycle Stem

To keep the weight and cost down, I used the very stiff Shimano PRO Vibe 7S OS Alloy road bicycle stem on my LOOK 595 Ultra; the alloy stem is very strong and stiff.
But for the ultimate in stiffness for a road bike stem, the Shimano PRO Vibe Sprint Mark Cavendish Star Series stem is the ultimate.
At about $250 @AMAZON, it’s not cheap, but if you must have an ultra-rigid stem, it’s the way to go.
Weight
Note yet tried, and I have not had a sample to weigh, but it reportedly is about 255 grams (about 120g heavier than the Shimano PRO Vibe 7S OS Alloy Road stem and more than twice the weight of the Ritchey WCS260 alloy stem).