The problem isn't that riders lie. It's that a paper log proves nothing: it gets lost, filled in after the fact, rewritten. And an hour meter can be reset to zero. The upshot: even a spotlessly maintained bike gets haggled down like a shady one.
We started HOROTAG to replace crumpled receipts and tampered meters with mathematical proof. Today we offer three devices doing the same underlying job, sealing an honest logbook: HOROTAG RUUVI (Bluetooth sync, €129), HOROTAG GPS (4G cellular tracker + anti-theft, for every rider, €299) and HOROTAG ULTIMATE GPS (4G cellular + detailed GPS track + alert when the bike sets off, road as well as off-road, €399). Only RUUVI counts hours and seals them: ULTIMATE GPS estimates hours and mileage from trips, and GPS estimates hours from the length of your rides, with no mileage. The sealed service log itself is identical across all three. No trust required.
At resale, one QR code to scan is all it takes for a buyer to see everything: with no way to cheat and no way for you to fudge the numbers. It's shorter than a lie, simpler than an argument, and infinitely more credible than a box of receipts.