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-   -   Single speed with two rear cogs? (https://www.bikeforums.net/mountain-biking/352989-single-speed-two-rear-cogs.html)

sprintcarblue 10-12-07 09:41 PM

Single speed with two rear cogs?
 
It's hard to find a that happy medium on road/off road gearing for my karate monkey. So instead of running 28-17 I was thinking about putting on 25-14/16 and I could switch depending on what the conditions were. Have any of you tried anything similar to this?

Thanks!

mx_599 10-12-07 11:33 PM


Originally Posted by sprintcarblue (Post 5445373)
It's hard to find a that happy medium on road/off road gearing for my karate monkey. So instead of running 28-17 I was thinking about putting on 25-14/16 and I could switch depending on what the conditions were. Have any of you tried anything similar to this?

Thanks!

using a spring loaded chain tensioner would probably work well. like a rohloff.

fixedup 10-12-07 11:33 PM

Are you talking about a dingle cog or a flip flop hub?

mx_599 10-12-07 11:42 PM


Originally Posted by fixedup (Post 5445766)
Are you talking about a dingle cog or a flip flop hub?

that's true, i wasn't even thinking flip flop hub. plus i just remembered it has horizontal dropouts. in the post above i was thinking the simple reach down and manually switch the chain idea if the cogs were next to each other without any axle adjusting.

Aaron_F 10-13-07 08:20 AM

Why not just run a full cogset in the back until you figure out what the perfect gear is for you? Put it in one gear, leave it there no matter what, and see if you can make a full ride that way. If not, keep experimenting until you find what works best. Then just ditch the cassette and get a single gear.

bh357 10-13-07 08:50 AM

Not cheap, but this would suit your purpose.

http://www.dirtragmag.com/images/125whitebros.jpg

http://www.dirtragmag.com/print/article.php?ID=830

sprintcarblue 10-13-07 09:00 AM

well, I am just running a cassette hub. So I just pulled most of the cassettes off. The off road things I ride are very hilly, but my daily cruising to and from campus is very flat and I spin like a gerbil trying to make it to class. I figured 2 gears one either side to my 25t front sprocket so they chain alignment is barely off would be ideal for my situation.

C Law 10-13-07 09:29 AM

That'll work, you'll probably need a tensioner, unless you get it so the 25x16 is at the extreme front of the dropout, then you could probably fit the 14 at the back without a tensioner, just sliding the wheel back in the dropout (although, depending on if you are running a rear brake, it would be annoying to have to re align the brakes everytime you switch gears)

If you are looking to keep the wheel in one place, then you will need a tensioner like mentioned above.

chainline shouldn't be much of an issue if you keep the 2 rear gears tight like they are positioned in a cassette.

sprintcarblue 10-13-07 12:36 PM

I forgot about the brake issue. I usually carry a tool with me and if I have to move the wheel i may as well just re adjust the pads.

Good point on the tensioner. I'll have to save up for a surly tensioner. It's kind of a pain trying to align the wheel and get the chain tight anyways.

jgsjr 10-13-07 07:10 PM

This works for me.....

44:15 for the road and 42:18 on the trails. No chain tensioner needed. Drop the rear wheel to change ratios

http://i50.photobucket.com/albums/f3...rontDouble.jpg

http://i50.photobucket.com/albums/f3...Reardouble.jpg

http://i50.photobucket.com/albums/f3...sandCogs-1.jpg

knucklesandwich 10-13-07 08:40 PM

I did the same, though with a Surly tensioner.
38x20 and 42x16 side by side.

Tall gear for farting around, and lower gear for mtn biking...


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