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Belt drive single speed

Old 10-13-21, 03:34 AM
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Vixar
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Belt drive single speed

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 !
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Old 10-13-21, 08:55 AM
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VegasTriker
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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,


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Old 10-13-21, 02:24 PM
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ofajen
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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 donít 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 1/8Ē 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 didnít see any 52.

However, 55/24 would be about 2.3 and they do have 24 tooth cogs. That would require about 1/4Ē 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 1/4Ē and the shortening of the BB to axle length changes both top and bottom paths on the belt, so 1/8Ē net axle shift per net additional tooth.

Hope that helps.

Otto
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Old 10-13-21, 07:31 PM
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My only advice is to get rid of that belt drive and get a chain drive.
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Old 10-13-21, 08:09 PM
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ofajen
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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 arenít too big. YMMV, but it might be worth a try.

Otto
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Old 10-13-21, 11:59 PM
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Thanks to everyone, except wolfchild ! Iíll report back.
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Old 10-18-21, 01:07 PM
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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?
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Old 10-18-21, 01:27 PM
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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.
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Old 10-18-21, 01:48 PM
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The only solution is a new bike.

https://spotbikes.com/products/acme-...31914008117282
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Old 11-03-21, 01:20 PM
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Vixar
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Originally Posted by ofajen View Post
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 arenít too big. YMMV, but it might be worth a try.

Otto
This is what I did ! So far, so good.
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Old 11-03-21, 03:25 PM
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Nothing wrong with adding another SS with the appropriate gearing.....
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