I just did a 300k last weekend (actually a 309k, 192 miles or so) and took 19 hours and 55 minutes to do it. And it was a good ride and I'm glad I worked it the way I did, and wouldn't do anything different. It's not always about speed.
I'll report back if I hit any speed records on the new bike, though.
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"be careful this rando stuff is addictive and dan's the 'pusher'."