Originally Posted by
dvai
Is a new bike. Sirrus X5.0
Has a 40T single ring on the front and a Shimano SLX M7100, SGS, 12-speed rear Derailleur. The cassette on the rear is 11-51t.
What would be the easiest way to improve speed?
Change the cassette? If yes, which ratios?
And would a large cage rear derailleur accommodate that cassette?
She is not going to ride any faster just because you change the gearing. I’m guessing she doesn’t have monster power and so won’t be speed limited by a 40-11 gear if there are no major downhills.
I would let her ride the bike and see what gears she uses. If she never goes anywhere near the 51T on the back then you might want to get a closer spaced cassette. But I would try it first.