I have a Trek SC 7.0 2014 model bike and have been upgrading on and off since purchase.
I’d now like to buy an asymmetric chain ring and am looking at the following Rotor options:
Rotor Flow 110 Compact Cranks - the length on the Trek is I believe 172.5mm, I am thinking of upping to 175mm to get more rotation.
Rotor QXL Chainrings 110 BCD - I’d probably take the 52/36 for where I live.
Do I need to give the bottom bracket any thought? I heard that the Trek is not compatible with the BB30… what do I need do / buy???
30 mm cranksets can not fit easily on the bb 90 of treks. You would need a special bb and a crank with a long enough spindle.
I would stay away from that for a number of reasons.
You would need a 24 mm version of the rotor crank (not sure of flow versions available, but rotor Des make a 24 mm spindle crank)
As for the length change…doesn’t really work like that as I assume you are thinking that it will increase power or something similar. But change if you want.
The Trek needs a Rotor 3D24 (formerly just “3D”) crank. If you have a Shimano crank there right now, the 3D24 just replaces it without any change to the BB necessary - if not, get the Shimano parts from Trek, since it’s the same spindle as Shimano.
Match it up with whatever chainrings you like. In fact, if you have a standard compact crank right now, why not get just the rings? Assuming it’s not a proprietary setup (like Shimano’s new stuff, or SRAM Yaw), you can replace just those and keep the old crank.