Bought a brand new bike in June with a Shimano Nexus SG-C6000-8D, 8 speed hub. It's a great bike for commuting but the problem is it's started slipping in 4th gear only. I've followed all the advice about usage, i.e. lining up the yellow marks, not standing on the pedals, easing off when changing gear. I can't believe there's anything seriously wrong as I only do 12 miles a day round trip to work on the road and a paved cycle path.Can anyone suggest what may be wrong?
I did not find the right solution from the internet.