5 steps to replacing chainrings. New and old drivetrains. Bike Service School. Lesson 9.

0:00 drivetrain problems
0:51 1. teeth number
3:31 2. chainring mount
7:41 3. chainline / offset
8:54 3 mm boost offset
9:50 chainline measurement
10:55 O.L.D. explained
13:57 4. chainring model
14:31 dremel hack
16:10 5. Shimano 12s only
17:27 YOUR TEST
B.C.D. Bolt Circle Diameter = P.C.D. Pitch Circle Diameter
How to calculate B.C.D.:
- 5 bolt chainring
A x 1.701 = B.C.D. ("A" is center-to-center dimension between bolt)
EXAMPLE 64.7 mm x 1.701 = 110 mm B.C.D.
- 3 bolt chainring
A x 1.155 = B.C.D.
Where to buy:
Shimano 12 speed chainrings amzn.to/3L1UWZ7
Sram 12 speed Boost chainring amzn.to/4c0bFYk
Sram 12 speed 6 mm non - Boost offset amzn.to/3XEOI95
Shimano 12 speed Deore cranksets amzn.to/3z31cwP

[@benthekiter1060]

Fantastic. I now have learned how simply the chain line in mm can be identified and measured

[@Deckzwabber]

Thanks for explaining this!
It really should not be this complicated, but here we are. I have three different bikes and three different crank systems.
Edit: at least I can switch out pedals between them.

[@hudsoncivil]

Geralmente eu me preocupo mais em alinhar a linha de corrente no Cog maior do cassete ( por que é onde geralmente se faz mais força e gera maior desgaste nos itens da relação) quando estamos nos Cogs menores do cassete geralmente é em descidas e só giramos o pedivela para não perdermos velocidade, causando menor desgaste nos componentes da relação.

[@clovercover5321]

great video, thx!

[@rossmarino7977]

So much information 😮good to know 😊how can you run that again 😅

[@wanderer2246]

Then I do DREMEL!

[@LunguPetreBogdan]

Hi! If i fave a 6mm offset chainring 32T and i want to change it with 36T i should chose the same offset?

[@EpicEvolution]

Yep

[@sgfahhdhsdhd]

Some good info, but some important stuff is missing, You keep talking about the chain line, and even show how to measure it, but you do not explain clearly enough its importance for shifting and tire clearance.. The talk about boost is also confusing and nor completely relevant to the subject (chainrings). An experienced bike mechanic will understand, but a beginner will be confused,

[@aa1320]

first