Hi -

I'm mulling the idea of building a road bike with a single speed kit/cog in the back with a double crank on the front, with a front derailleur.

Ideally I'd like to use just a chain tensioner. And if so, is there a chain tensioner you would suggest?

Doable?

Thanks.

RoadUno - Reportage Thread
-- i'm hurt you haven't deeply studied my reportage thread. deeply....

also - BSNYC was running his single RoadUno with two speeds. I think he's back to a single single speed.

Bike Farmer has set his RoadUno up 2 speed. He's got about 3 in-depth videos posted.
to wrap up - totally doable. Probably easier w/ a dedicated chain tensioner. Like a low cost one would be fine. Or if it's a nice bike and you want to impress..... almost no one - get a spendy Paul Melvinator like I did.
If you use a regular derailleur, it might take more fidgeting. and I think people have more skipping problems. I think more tension is better.

Probably use an 8spd chain and not a dedicated single speed ? 1/8th in ? chain, as it's less flexy.

enjoy!

This is the single speed forum. However in the end you could do it but why? I think it is a cool experiment and certainly if you have all the other types of bikes go for it but I have never loved front derailleurs so I don't know if it is for me.

mrv,

I'm deeply sorry for not studying your prior reportage. I have now remedied my lapse, having read every word of the thread. I feel enlightened. And BTW, that's a very cool bike.

I have also watched Bike Farmer's Roaduno videos, having only fast forwarded a few times, and I feel even slightly more enlightened. I think.

I hope this assauges your dented feelings.

As you will see in the picture below of my converted Vitus, I am familiar with Melvins, including my cousin Melvin. I managed to run into that one used (the tensioner) for only $50 from a bike club pal.

Yeah, I have an 8 speed chain on the Vitus, but I like the idea of using a 1/8" chain for a 2 speed.

Stupid question that I hope you could provide guidance on: Where should I run the chainline? In line with the small cog? Large cog? In between?

Many thanks.

I am having fun.

Why not just use a flip flop for a nice change of gear inches?
This will prevent attempts to use a FD and get a working chain line, especially with a 1/8 chain.
Sure, its not shift but flip flop but still give you options for difficult terrain changes.

If you use 1/8" chain, make sure the space between chainrings is sufficient to prevent scraping on the large ring when running on the small ring.

Not stupid at all. Ideally, a line through the rear sprocket should end up between the two front rings, and parallel to the plane of the frame.

~ very nice color scheme ~

For my RoadUno three-speeded single speed, I tried to get the rear cog centered on the crankset. Creates the least 'cross chaining' (.... can you be cross chaining with just two chain rings? dunno...)

I think I could make an argument for aligning the cog and large ring, as now the whole system will now be subjected to the most stress (more tension in the chain from the tensioner and from pedaling with a longer lever arm (i.e. larger radius ring)). And if you are using a stiffer 1/8in chain, it will less accommodating to the mis-alignment under more stress.
A relaxed tensioner in the small ring, and the lower torque applied would, I think, be more accommodating to be cross chained..... unless your climbing hard !! ... oy.

The Rivendell folks recommended an 8spd chain since it's supposed to be more flexy. I guess thinner plates than an 1/8th in chain. I could as the Mighty-Mighty AI, but i hear ignorance is bliss.
https://www.rivbike.com/blogs/news/y...Z3vE57fTab71cy
- scroll down mid way.

Looking forward to your results -- and hoping we don't get into too much trouble talking multi-gears here in the one-gear forum. :|

How about find an old 2-speed hub from an old Schwinn bike and build a 700C wheel out of it? My old 1970 Schwinn Stingray had one of those - 2-speed kick shifter. Fun, fun bike to ride!

Great. Many thanks John D.

Thanks for all mrv. I'm leaning back to using an 8 speed chain. Re placement of the chainline i get the point about aligning with the large ring, but I should be able to futz around to get it right. It'll be a while but I'll be sure to post the results.

My Fargo is a dingle speed. 2 chainrings, and 2 cogs that take the same chain length. I have to use an allen wrench to move the pully over on the Surly tensioner to change from road to trail gear.

I've not gotten any feedback in my post to the MechaniX files: ss'ing a vintage ATB w/ a hollow crankset

any advice on properly selecting parts for correct chainline when using outboard bearings with a 73mm shell and 135mm rear spacing?

thanks.

My 2spd. It's going to be a 3spd once I decide which cogs to use. When I get a round to it.

OP you inspired me to do a 2-spd conversion on my '91 Schwinn Mirada 650B Mtn/Hybrid bike. A friend gave it to me a couple of weeks ago and I tore it down to the bare frame for a winter project. Hopefully it will be done by this Spring. Stay tuned!