Thanks to the description provided by EmoryDPTT, I’m looking for countersunk bolts long enough to traverse the base bar, 65-70mm of spacers, and the bottom of the extensions, i think it’ll have to be at least 90 mm (body + head) as the current ones i have are 80mm and i need probably another 1.5mm of stack.
The longest bolts that Shimano sells is 80mm (ones that I have) and is not long enough. I was told that the Specialized Tri Shiv spacer kit has longer bolts, but given the recall, i’m not all that inclined to purchase them. I’m not so sure. If you have extras or know of someone who may be able to make a custom set, let me know.
Thanks to everyone for the suggestions. Turns out i needed a M6 bolt as opposed to a M5. Fortunately, McMaster does sell M6 in 100 mm, and it works just fine with my aerobar
Would also definitely recommend McMaster if you need to purchase bolts or that test weight to calibrate your power meter