I want to swap the stock e13 34t chainring on my Trek Rail 7 Gen 2 for a 32t ring. My local trails are technical with lots of punchy climbs and granite. I find that I'm hardly ever in the smaller cogs and a smaller chainring helps with the trials moves that my local trails demand. If I swap the chainring for something with fewer teeth do I have to take the bike back to the shop for reprogramming?
Rail (750Wh) Trek Rail Chainring Swap, Is Reprogramming Required?
- Thread starter BuckSaw
- Start date
JP-NZ
E*POWAH Elite World Champion
No, I don't believe so.
- Thread starter
- #4
I spoke with Trek support today and they told me that a change in chainring size on the Rail 7 requires reprogramming. Unfortunately my local Trek dealer sucks. They had my bike for two months last summer to replace the crankset under warranty, and didn't replace the crankset.
Personally I would fit the smaller chainring and see what happens!
If it throws some errors up then swop back and then think about getting it reprogrammed.
On my gen 2 Bosch motor I put a bigger chainring on without any issues despite being told it won't work without being plugged in and altered.
If it throws some errors up then swop back and then think about getting it reprogrammed.
On my gen 2 Bosch motor I put a bigger chainring on without any issues despite being told it won't work without being plugged in and altered.
schra
Member
I changed the chainring from 34 to 38 on my 2021 trek rail without reprogramming, after 4000 kms no errors yet
