Hi, i'm a newbie to a-bikes. Purchased a Haibike Yamaha SDuro Cross SL 3 months back, as my commuter bike. I'm riding with a dongle, predominately on back roads, but as I'm nore of a roadie, i'm finding that the 38t chainring is not big enough. Can anyone advise what I can upgrade this to. I've been advised that its a 104 BCD 38t.