Uploaded May 2026 | Updated September 2026, 2 weeks ago
The Impossible Deadline. A regular customer dropped off his Trek with a shattered shifter on Thursday and a flight to catch on Tuesday. The destination? Somewhere with very steep hills. The problem? 11-speed replacement parts are scarce and expensive, and his BB90 bottom bracket was literally falling out of the frame.
In this video, we navigate the parts bin crisis, explain why we chose a full 12-speed Shimano upgrade over a "standard" repair, and perform a "lethal" bodge by exceeding the rear derailleur's max capacity to give him the climbing gears he needs.
We dive into:
Trek BB90 Repairs: Using the Token screw-together solution for worn carbon shells.
Mechanical Sympathy: Why cross-chaining on this setup could be a "mechanical catastrophe."
Derailleur Capacity: The math behind the 39-tooth limit and why we ignored it.
Crank Length: Swapping 172.5mm for 160mm for better ergonomics.
Warning: This setup requires a high level of mechanical awareness. Don't try this at home unless you're prepared to stay out of the "big-big" combination!
## Video Chapters
00:00 The "Tuesday" Deadline Challenge
00:44 The 11-Speed Parts Crisis
01:28 Chain Suck & Worn Drivetrains
02:21 The Cost of Sourcing Rare Parts
03:14 The 12-Speed Upgrade Proposal
03:58 Trek BB90: The Carbon Shell Nightmare
05:41 Using Feeler Gauges to Check Frame Wear
07:15 The Token "Screw-Together" Solution
08:18 Frame Protection & Cleaning
09:09 BB Installation & Assembly Grease
11:09 Why we chose 160mm Cranks
11:50 The "Lethal" Chain Sizing Risk
13:55 Setting Chain Length for Extreme Ratios
15:54 Derailleur Capacity Math Explained
18:36 4 Ways to Get Lower Gearing
19:32 The Final Bill & Mission Success
The Impossible Deadline. A regular customer dropped off his Trek with a shattered shifter on Thursday and a flight to catch on Tuesday. The destination? Somewhere with very steep hills. The problem? 11-speed replacement parts are scarce and expensive, and his BB90 bottom bracket was literally falling out of the frame.
In this video, we navigate the parts bin crisis, explain why we chose a full 12-speed Shimano upgrade over a "standard" repair, and perform a "lethal" bodge by exceeding the rear derailleur's max capacity to give him the climbing gears he needs.
We dive into:
Trek BB90 Repairs: Using the Token screw-together solution for worn carbon shells.
Mechanical Sympathy: Why cross-chaining on this setup could be a "mechanical catastrophe."
Derailleur Capacity: The math behind the 39-tooth limit and why we ignored it.
Crank Length: Swapping 172.5mm for 160mm for better ergonomics.
Warning: This setup requires a high level of mechanical awareness. Don't try this at home unless you're prepared to stay out of the "big-big" combination!
## Video Chapters
00:00 The "Tuesday" Deadline Challenge
00:44 The 11-Speed Parts Crisis
01:28 Chain Suck & Worn Drivetrains
02:21 The Cost of Sourcing Rare Parts
03:14 The 12-Speed Upgrade Proposal
03:58 Trek BB90: The Carbon Shell Nightmare
05:41 Using Feeler Gauges to Check Frame Wear
07:15 The Token "Screw-Together" Solution
08:18 Frame Protection & Cleaning
09:09 BB Installation & Assembly Grease
11:09 Why we chose 160mm Cranks
11:50 The "Lethal" Chain Sizing Risk
13:55 Setting Chain Length for Extreme Ratios
15:54 Derailleur Capacity Math Explained
18:36 4 Ways to Get Lower Gearing
19:32 The Final Bill & Mission Success
