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I'm wanting to set up my commuter/winter mtb with two gears, one for roads/flat easy trails, one for techy trails. I want to be able to hop off the bike and switch gears in a few seconds without using tools.
My frame isn't single speed specific, but I'm not sure that makes a difference in this case.
Three options I can see:
1) Run a single sprocket at the back, two chainrings at the front and a two-piece tensioner at the back, which can take up the slack. This works ok, can be tricky to get the tension ok in both gears, the chainline isn't perfect, and the tensioners are as exposed as a rear mech so more susceptible to damage. And it's a bit ugly, but may be all these things are.
Basically this but with no mech:
https://maxthecyclist.wordpress.com/2015/10/08/karate-monkey-two-speeding-with-my-friend-melvin/
2) Run two sprockets at the back and two rings at the front, with a standard tensioner like a Surly Singulator set-up halfway between the rear sprockets. I've never tried this, obviously the chainline and tension problems of the above would be solved (by running say 16t-34t and 18t-32t), but I'm not sure the tensioner can just be put in the middle without causing problems(?)
3) Run a single chainring and two sprockets at the rear, with a bb mounted sprung tensioner like this Yess thing. Still slight chainline issues, but I think I like this idea best. Problem is that Yess thing appears to be the only option and it's £50... Is there anything else out there?
Thoughts/experiences?
Two chainrings and two cogs.
You get a better ratio jump and ifyoh match the difference front and back you will be close in tension.
But really...
3speed igh because stopping and chainging your gearing is a pain in the hoop.
As ridden by Sean Kelly.
I've used the two-rings-two-sprockets setup, and as noted above it works really well because if you go in steps of the same tooth count (one up, one down) at each end you end up with similar effective chainstay lengths. You can even go "tringlespeed" this way.
That said, I've only done it with track ends, not with a vertical dropouts and a tensioner. I'd probably be inclined to see if I could bodge a Singleator style device to have more float on the jockey wheel, but I don't know how easy that would be… probably not very.
joshvegas
But really…
3speed igh because stopping and chainging your gearing is a pain in the hoop.
This is what I do generally. The 3 speed hubs are quite light when you consider how much steel is in them.
However sometimes the low gear you want is too far out, eg on my fat bike I run 32/22 for general trail work, and 22/32 for bogs, snow etc.
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The best way to run dinglespeed is have the sum of the front and rear cogs equal, eg as I have there, or something like 42/16 (=58) and 36/22 (=58) which is what I'd use on a roadster that ventured offroad.
It's worth trying to find a magic ratio so you don't need a tensioner. Much more satisfying than a tensioner. 🙂
(If you do magic ratio, it's best to use steel chainrings because they wear slower and so you don't lose tension.)
Never tried it but would 2 cogs front and back work with a singelator that's been bodged to hold 2 jockey wheels (one for each chainline)?
I'd be tempted to use an old rear mech (as I've used after attempting to buy a chain tensioner from big Al and being asked if I didn't have any old knackered mechs I could use instead) with a short section of cable holding it in place from the stop to the clamp, then suss out a number of turns of the barrel adjuster or a shim to move it between the two.
The best option is to use 2 rings and 2 sprockets, but if you're using a tensioner anyway, why not use an old rear mech? A bit of wobble still won't matter.
I ran my hardtail as a dingle speed for about a year.
Single cog on the back and 2 on the front. I used a Pauls Melvin tensioner (though and old mech would have done just as well), and used my heel to change down the gear when necessary.
I only had to stop when I wanted to put the chain back on the big ring.
I ran 36t and 24t rings, with an 18t rear. But you could go lower or higher than that easily.
It was great, and I never really felt I needed more gears. Though I've recently fitted an Alfine hub to the bike (cos why not!)
I run two cogs on the back. Surley 15 and 17T on a Hope freehub. My frame has horizontal dropouts so can take up the slack easily. The 32T chainring is still too small for road, but the two gears is nice. Used it for cross racing too. It’s a 26er for those that care.
Well it turns out I had to leave work yesterday as a migraine meant I couldn't look at a computer screen, but playing with tools in the garden helped 🙂
Also turns out I had enough stuff to try something out. I put an alfine tensioner on with 18t and 21t sprockets at the back, matched with the 37t chainring that was already on there. The sprockets are so close together that it works with the Alfine set up halfway in between. There's a little noise but nothing intrusive, and there certainly isn't anything rubbing. Takes only a couple of seconds to change gear.
I’d probably be inclined to see if I could bodge a Singleator style device to have more float on the jockey wheel
I can't think how to do this, but what I will do if put a worn jockey wheel on the top so the chain has a bit more lateral movement. Given it already works now I reckon this'll do it.
The two jockey wheels idea is a good one, if I ended up adding another chainring to the front I may try that. Or the rear mech with a short length of cable idea, that's a nice fix. That would be good as I'd technically then have a fingle speed, if all four combinations of cogs were different. Although that's beginning to defeat the object of not having gears 🙂
An internal hub or crankset would certainly be nice, but way beyond the budget of this bike...
Now I see I need to sort the chainline... Hard to get that Alfine any further out, so going to have to shift the chainring inwards
...and...
Looking at those pics again, there's really not much slack in the system when moving from the big to small sprocket. Reckon I could get away with a standard single-jockey-wheel tensioner?
Ooh, those sprockets are *close*.
I'd at least try a single-arm tensioner. The current configuration's at the point where you might as well just add a shifter and a cable 😉
Ooh, those sprockets are *close*.
Ya, I was surprised I could get them that close with no rub, but then I measured it up next to a 10sp cassette and it's basically the same (that is, if sliding two butter knives into each gap counts as taking a measurement...)
I’d at least try a single-arm tensioner. The current configuration’s at the point where you might as well just add a shifter and a cable 😉
I've wondered that tbh... However, it seems I've had that Alfine for at least 7 years and it works like new despite me not doing anything to it and having ridden it pretty roughly 🙂 So still a lot simpler than a gearer set up
