Vixar

Hi everyone, this is my first post here !
I have a Trek District 1 single speed front 55, back 22 - Gates CDX system, so I have a 2.5 gear ratio. I will move in an area with more hills, so I would like to have an easier, 2.3 gear ratio. What is the cheapest way with less work/trouble to achieve this ? Can I replace only the front chain ring with a 52 and adjust the belt tension (if yes, how ?) ? Or do I have to also buy a new belt (and maybe other things) ? Thanks in advance !

VegasTriker

First off, I don't own a belt drive bike but a quick look at the Gates website lists an owner's manual for their products. https://www.gatescarbondrive.com/~/m...rive.pdf?la=en As I suspected, the tension on the belt is critical to making it work. The picture below shows the tension adjustment points on your bike. It doesn't look like there is a lot of room to make the adjustment. While not cheap, one solution would be to have the wheel rebuilt with a 3 speed hub such as the Sturmey Archer hub and use the same drive train parts you already have. That would give you a wider range on both ends,

ofajen

Typically you should be able to change rear cog or front sprocket and adjust it if there is room for any net shift of the axle.

I don’t have specific experience with the Gates, but if they have two teeth per inch of belt, like a standard chain has two links per inch, then each tooth of net change in the sum of front and rear moves the axle about 1/8” or 3 mm.

Is there actually a 52 tooth option in front? On the Gates website it looks like there are 50 and 55 in at least some lines, but I didn’t see any 52.

However, 55/24 would be about 2.3 and they do have 24 tooth cogs. That would require about 1/4” or 6 mm of room to move the rear axle forward in the slot due to the same belt having to span the larger cog.

Note: the belt only sees the outer half of the front sprocket and rear cog, so each net tooth adds half of a belt tooth length or 1/4” and the shortening of the BB to axle length changes both top and bottom paths on the belt, so 1/8” net axle shift per net additional tooth.

Hope that helps.

Otto

wolfchild

My only advice is to get rid of that belt drive and get a chain drive.

ofajen

Also, I might add, you might try it with the current gearing. If your bike has 700x25s and 55/22, that is about 66 gear inches, which is a very reasonable choice for SS with some hills, if they aren’t too big. YMMV, but it might be worth a try.

Otto

Vixar

Thanks to everyone, except wolfchild ! I’ll report back.

Pratt

If you have, or have access to a bike with a variety of gears, perhaps use that to determine the ratio appropriate to your new home. Then you can ask the simpler question: How can I convert my SS to ratio. X?

Iride01 

If you live in hilly or rolling terrain, I'd recommend a multi-speed bike. Whether that's a belt drive on an IGH (internal gear hub) or a chain drive with a derailleur system, that's your choice.

For me, the issue with a single speed bikes are that if the gear ratio is appropriate for climbing a hill then it's very inappropriate for going down the other side of the hill and even inappropriate for cruising on level terrain.

prj71

The only solution is a new bike.

https://spotbikes.com/products/acme-...31914008117282

Vixar

This is what I did ! So far, so good.

Speedway2

Nothing wrong with adding another SS with the appropriate gearing.....