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I'm planning to go on a long cycle this year and that last 20k is up a steep incline. I noticed i had to walk up the inclines that were steep and i thought i would have got a lot further if I had one or two lower gears.

I've got a cube travel pro 2020 (https://www.cube.eu/2020/bikes/tour/travel/cube-travel-pro-blacknbrown-2020/). Shimano nexus 8 speed gear hub.

i'm hoping that i can get a smaller front sprocket and larger back sprocket to lower the gearing ratio ? if so please confirm and if you have more knowledge help on my selecting the right combinations so that they will fit the current belt size. youtube installation videos or anything to bring me upto speed.

Another option would be for me to upgrade to an alfine 11 speed hub. I guess that's a solution, it would help if i could sell the 8 speed hub afterwards. https://www.veercycle.com/blogs/getveered/how-to-choose-an-internally-geared-hub

Thanks, Pat

ravensburg, germany

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    For all interested: the bike is described by the Cube site as having 22T on the cassette and 46T on the crankset, with a Gates belt with 120T – EarlGrey Mar 5 at 8:52
  • First of all, use the gates calculator to see what sprocket sizes work with your belt. The belt is cheaper than the sprockets and you may find you can get a new front sprocket and belt for not too much. Your existing belt and sprocket will retain some value and can be re-sold depending on condition. – JoeK Mar 5 at 9:12
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Apparently on the front you can’t go smaller than 46t (you have the 130mm diameter front sprocket).

On the back you can change from 22 to 26t which would make it 18% easier.

It would be in violation of Shimano’s recommendations:

•The cassette joint should only be used with sprockets with 16T to 23T.

•The gear ratio of the front chainring to the rear is about 2.1-to-1.

But I think it’s fine, considering that the ratio (and therefore torque at the hub) is still relatively harmless

The lowest gear of the Alfine 11 is 7.5% easier not easier than that of the Nexus 8.

Edit: No idea where I had the number from, I now looked up the official specs, the easiest gear is identical between Alfine 11 and Nexus 8. Both have "Gear ratio_1 0.527"

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  • Thanks everyone for the quick and great advice/tips. Imagine if i installed the alfine 11 at that expense and time effort only to find out it's 7.5% easier than the nexus 8 (i'd be kicking myself and blaming myself for not doing enough research). going to look at getting a 26t . Would i need to change the belt drive as well ? – padjo Mar 5 at 9:26
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    Sprocket looks good. According to this calculator if you currently have a 22t rear sprocket and 120t belt, increasing to a 26t rear sprocket means you need a 122t belt. Unless you can slacken the tension (i.e. decrease the center-center sprocket distance) of your current belt by 1cm. gatescarbondrive.com/~/media/files/gcd/… – Michael Mar 5 at 13:21
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    Looks good to me, but I’m no expert on the Gates, I don’t own one, I only find them interesting and follow the development. – Michael Mar 5 at 16:39
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    One reads bad things about the CDN (rear sprockets and belt) on the internet, so I think the upgrade to CDX is a good idea. – Michael Mar 5 at 16:43
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    It was my second time back to him and he's extremly busy but he quickly explained what he meant the first time, flipped the nuts and sent me on my way. I've learned a lot and can do a lot more myself. if i left it to the bike shop, i'd be down a lot of money and knowledge and have to wait two weeks. Everything looking good now. Hopefully i can climb steeper hills this year. thanks everyone – padjo Mar 11 at 15:19

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