Should there be this gap between my zumo wheel and 1,85 spacer/8speed cassette??
What else should be there? Strawberry Jelly?
Your chain could use some oil 
Is probably fine.
You will probably never use that gear.
I assume this is your mountain bike and that cog is a 34 + tooth cog.
Also, if you’re on the big chain ring on the front, you probably shouldn’t try to be on the “big” gear in the back.
That situation is a case of being in the hardest gear on front and the easiest in the back and the chain gets tight and is “crossed” and things make weird noises.
Thanks for the sensible answer!! As zumo does all the ascending do I actually need to change gears?
If you’re fine doing <20rpm or so, nobody forces you to change gears.
Do you change gears when riding outside?
1 Like
I would put the back gear in about the middle or slightly more towards the smaller gears.
@Wayne_Bennett_CRYO-G I think we may be missing your point. Is there truly a “gap” in there? Is the spacer the black part to the right of the arrows or the silver part under tip of the top arrow and at the tip of the bottom arrow of the first picture? i.e. is this really a literal gap such that the cassette can slide left and right a little? If the cassette and slide left and right, your shifting will be poor and ride roughly as the cassette will keep moving back and forth on you. If that is the case, measure the gap (looks like 1.5mm if the black is a 1.85 spacer, and stick another spacer in there. The cassette should be rock solid in place on the hub.
I had to add one more spacer than anticipated when I put a 7-speed onto my Kickr Core.
You need extra spacers for 7-speed onto an 11-speed hub. But a 1.85mm spacer is sufficient for 8-speed onto an 11-speed hub.
What spacers would I need for 7 speed on zumo as been offered a road bike???
I put a 7-speed onto a Wahoo Kickr core. I started with a 4.5mm spacer and found it was not enough. I then added another 1mm and that made it snug and aligned well with my drivetrain. Start with 4.5mm and see if that is sufficient. If the cassette slides a little then add however much more is needed.
You will likely need to file 2 notches into the 4.5mm spacer for the two rivets that protrude through the back of the cassette. See this forum discussion in which I included photos of the spacer. I remember seeing a video that showed this concept but I can’t find it now.