Single Speed plus Granny - will it work?

[SkipdiverJohn]

If you want to simplify to get rid of the gear mechs, I reckon you're using the wrong bike as a base as it's got vertical dropouts. If you were to use a horizontal drop out frame, you could do an el cheapo SS conversion by simply removing all the gear mechs and shortening the chain to suit whichever rear sprocket you decided to use.
I've considered doing this to my pub hack MTB, but I don't need much climbing ability. ATM, I run on the middle front ring with the mech removed and the rear mech functional.

 

[Threevok]

SS MTBing is clearly a nonsensical idea. I don't know why I feel the urge to give it a go so strongly!

SS MTBing It's actually quite addictive, but takes some planning ahead, to set the bike up to suit the terrain and conditions at the time.

It also teaches you to "pick your battles" regarding where, when and how much power you put down, when encountering climbs and obstacles and also braking.

It's made me a better MTBer and even a better commuter, as you learn to anticipate things far earlier than you do with gears.

Plus my brakes last a hell of a lot longer than they used to.

Dingle speed on an MTB is probably only useful if you intend to do something like bike-packing on a single speed, where it would be required for greater distances and differences in terrain. They seemed to be popular for bike-packing in the US and Canada, especially in the snow on fat bikes.

If you do decide on the SS route, start with a 2:1 ratio first and work your way up/down from there

 

[Sharky]

I rode a fixed set up a while back with a double 42/52 chain set and a flip flop rear wheel with something like 14t & 17t.

I used the 42/17 (64") for riding out to events and general training, then turned the wheel and used the 52/14 (97") for the race. With horizontal track ends the chain tension was easy to resolve. May not have been these exact numbers, but was similar, giving one combination an easy gear and the other a very tall gear.

 

[Ajax Bay]

Would I need to put the 11t sprocket next to the lock ring (even though it would never get used... not that it does much anyway!) or is it OK to put one of the plastic spacers at the end next to the lock ring?

No it is not OK. The lock ring, even tightened to 40Nm, would not be secure against a plastic spacer. They put the knurling there (on the metal smallest sprocket) to enhance the fixing's security metal on metal, and to give that satisfying clicking sound as it's cinched.

 

[ChrisEyles]

@Sharky 52/14 is an immense gear, kudos for being able to turn that up a hill! That's the top gear on my 1960s ten speed, and only ever sees use bombing down long hills or with a good strong tail wind on the flat.

@Ajax Bay thanks for the advice, this is something I was very unsure about. Having looked at SS conversion kits I see they come with metal spacers which I guess are OK to tighten the lock rings against (even without the knurling)? However, for the purposes of this experiment I don't have a problem with a redundant 11t sprocket up against the lock ring. It is going to look bizarre enough in any case!

 

[Sharky]

@Sharky 52/14 is an immense gear, kudos for being able to turn that up a hill! That's the top gear on my 1960s ten speed, and only ever sees use bombing down long hills or with a good strong tail wind on the flat.
!

Only used on our 10 course, which does not have any hills, although the outward leg is a real graft.
As I said, may not have been a 52, but my current fixed TT bike normally has a 50/14 on it and occasionally a 50/13.

 

[ChrisEyles]

Haha, that's pretty much exactly what I'm aiming to achieve, only with less red boxes

 

[ChrisEyles]

Well - it's now a done deed!

Unfortunately my phone's on the blink at the moment but I'll get some pics up when I can pinch Mrs Chris's one.

Took a lot more faffing with spacers and sprockets than I was expecting to get the chain line right, especially since I decided to re-use the three rivets to link the two gears and a dummy sprocket in order to spread the driving force over a larger area of the splines. When I was finally happy with it, my cassette tightening tool slipped while doing up the lock ring (even though I'd stuck a Q/R skewer over the end) and took a chip out of the end of the freehub shell Annoying, but the lock ring tightened up OK second time around and the 11t sprocket that engages with the damaged spline never sees any use, even when the bike has shifters, so not the end of the world.

Other than that minor mishap, I'm pretty chuffed with it, and the "single speed with granny" idea seems perfectly workable, at least in the work stand. The barrel adjuster on the RD has enough cable pull to shift between the two gears on the rear and the RD itself seems to do a perfectly good job as a tensioner.

Will take it for a spin tomorrow if the rain lets up. I hope the 42/23 gear works out OK in practice as I don't particularly want to do battle with the cassette again!

 

[ChrisEyles]

Well here it is in all it's dubious glory I set it up first with a short riser stem and wide bars out of the parts bin to try and get a fun BMX type feel if I dropped the seat down, but it didn't feel great, and the riding position wasn't any good for putting power down. The longer stem and bar ends seem to be much better for sprinting/climbing, and the bike feels a bit more nimble too. It's gonna be a bit more hair raising on the way down anything tricky but that's all part of the fun and I'm lucky enough to have another more capable MTB for those sorts of rides.

The 42/23 gearing felt pretty good on an (admittedly short) test loop, including some good steep off-road climbs. Didn't use the 32/34 granny, but that's kind of the point, to have it in reserve for some of the longer Dartmoor/Exmoor climbs I know I wouldn't stand a chance getting up otherwise.

I think the derailleur looks OK as a tensioner. The 34t sprocket looks a bit strange, but no getting around that if you want a granny gear! I've also left the small ring on the crankset for now in case I decide to switch back to a geared set-up at some later date.

Despite being a double speed (dingle speed? SS with granny? I don't know...) I ended up with four sprockets, the two 23t and 34t gears, an 11t for the lock ring to bite on, and a 15t next to the hub as the plastic spacers were getting crushed when I tightened the lock ring without this. Since I was worried about gouging the cassette body I put the three rivet pins back through the 15t/34t/23t sprockets to hopefully spread the pedalling force out a little (ironic that I worried so much about this and then took a chunk out of the cassette body tightening the lock ring).

For a zero cost switch over I'm quite pleased with it.

 

[Threevok]

Very good job indeed - well done

Incidentally - If you ever want to spend some money on it you may want to invest in some single speed spacers and a 12t lockring - so you can despense with that unused cog

 

[ChrisEyles]

Cheers @Threevok!

Took the bike out for a great ride this afternoon on a couple of hours of very muddy woodland singletrack. Although the 42/23 gear was great for yesterday's short blast I found it quite a bit too high for a longer ride with more challenging climbs... and while I did use the granny 32/34 on one climb, to be honest it was far lower than necessary.

After around an hour I switched to the in-between 32/23 gear and left it there for the rest of the ride. I'd previously written this gear off as being too low to put up with while not climbing, but it actually worked out really well off-road, and wasn't even too much of a PITA on the road back home (maybe because I was too knackered to push a bigger gear by then). Funnily enough that's pretty close to threevok's 30/22 gear.

A bit more experimentation on different routes is clearly called for. But it'd be nice if I find 32/23-20 works out tolerably well so I can ditch the excess chain rings and sprocket.

 

[ChrisEyles]

Been out for a couple more short rides. The 32/23 is predictably infuriating on the road heading from home out to the fun bits so I wouldn't want it as the only available gear, but it's been great in my local woods, and I can use the 42/23 for the bit from home to the trails.

Some dark and rainy evening I think I'll swap the current 32 & 23 sprockets for 23 & 20 ones, which will give a few different ratios to try out.

It is admittedly a rather indecisive "single" speed! But great fun messing around on it so far, and I've been surprised that I've made it up a few climbs in 32/23 where I'd normally be dropping right into bottom gear and spinny-crawling my way up.

 

[Threevok]

Tinkering with the setup is half the fun. I am still experimenting after two years

Good thing is, single rings and sprockets sell on ebay for a good price. So you don't lose that much on unwanted ones

 

[Nigelnightmare]

Sorry! I still can't understand WHY?
Millions spent in R&D for multi geared bikes.
Plenty of options for different gear ratios out there and going by the problems your having with gearing and the terrain you're riding just stick with the front triple/ rear cassette that way you have the option of using a suitable gear ratio WHEN NEEDED.

Still...…."Your bike your rules".

 

[Threevok]

Sorry! I still can't understand WHY?
Millions spent in R&D for multi geared bikes.
Plenty of options for different gear ratios out there and going by the problems your having with gearing and the terrain you're riding just stick with the front triple/ rear cassette that way you have the option of using a suitable gear ratio WHEN NEEDED.

Still...…."Your bike your rules".

Indeed

I can't say I understand Gravel Bikes either - someone who really wants a road bike, but really needs an MTB ?

and don't even get me started on CX - like eating soup with a fork

But each to their own