I have a cheap old rockrider 5.0 mountain bike also known under the btwin brand. Bit by bit I'm trying to improve it's performance as a road commuter bike. So far I've changed the rear wheel to a cassette type and upgraded the cassette from 14-something T to an 11-28T and changed tyres from 2" semi-slicks to 1.5" slicks. This much improved it as a road bike but after 2000+ miles since the upgrade I'm noticing I often max the speed out on flats and would like a bit more gearing. 11T is pretty much the best I can do on the rear cassette so I'm considering upgrading the crankset from a 42T to a 48T or bigger if I can.
My current rear cassette is a Shimano Acera 7 Speed 11/28T Cassette CS-HG41-7. My chain is a KMC Z51. The front derailleur is a Shimano TZ30.
I'm aware that the front derailleur will possibly need to be adjustable to get the chain over the larger 48T chain ring. And possibly the chain may need to be lengthened.
The crankset I have in mind is Shimano Alloy / Steel Triple Chainset FCM131 28 /38 /48 teeth ratio suitable for 5, 6, 7, or 8 speed.Is this likely to work ? Can I go bigger? And what compatability considerations do I need to take into account in this upgrade?
It's my first time upgrading a crankset so any advice would be much appreciated.