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Aren't they specifically for motor paced racing? That's why they've got stem support as well and a reverse rake? Supports are for added strength at the speeds they obtain.

Extreme Strength
Some of the stems employed have stiffening gussets added; some are home-made from box section steel – pace following bikes are never light. This position also brings the saddle forward, the seat pillar is reversed and a support is fitted from to the saddle nose to the down-tube.

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