why isn’t the derailleur mounted above the wheel rather than below?

Because it needs to guide the chain into the sprocket. The front derailleur is mounted on top, the rear derailleur is mounted below because that’s where the chain is fed into the sprockets. If you wanted to only have a top mounted derailleur, you’d need to squeeze 12 sprockets into the bottom bracket area. The top part of the chain is under tension, so shifting under power would be a problem. You’d still need a tensioner somewhere under the chainstays because that’s where the slack chain is. If you want to move the derailleur away from under the dropout, the only realistic thing to do is to enclose it and use it as a frame mounted gearbox, which is not a new idea.

@tjagain. Alfine IGH isn’t a great solution for modern bikes though as it requires a QR rear end and doesn’t particularly like high torque. Not many frames are QR these days and whilst you can change gear standing still on an Alfine, they don’t like shifting under heavy load and can slip if you try. Not ideal for a MTB.

@jameso how many teeth would you want the lowest sprocket? or you had a 50 would you still not need a mech with the same dimensions?

13 or 14T – any smaller and I’ve had problems with jamming and skipping in winter. And it always seems daft to build in tighter radius sprockets. I’m not too worried about top-end gears anyway.

13-40 across 6 gears would have gaps like a double shift on an 11-34 cassette. That would work OK.
I’d like to see narrower freehubs to go with it, for less chainline variation and stronger rear wheels. I have a Jeff Jones mod rear wheel on one bike, a Hope SS hub with 6 9s sprockets on it (15-32 or similar) works well with a double on the front – all the range needed for bikepacking and no problems cross-chaining, you can use all 12 gears with a good chainline. I don’t get the full gear range available from a 1×12 but it’s not far off, close to an 11-42 1X. A wider ratio rear i/o a cut down XT 9s would fix that.

I think the real genius would be solving whatever issues it is people have with front mechs, then shifting all that weight and clutter back away from the rear axle.

Were internal geared cranks really so awful?

Funny you should say this, I’ve been riding my road bike ‘fake SS’, not shifting for most of a ride looking for a good SS ratio for a new build. Accepting that spinning out on the road is more dull than same situ on the SS MTB. Thinking about using an FD with a BB arm tensioner for 2 rings up front, ie 48T main gear and a 36T bail-out. Gives me a gear I can push most of the time, and a gear that means a ride in a hilly area won’t be impossible. Wales might be a bit too much o/c.

No logic to it, just I like riding SS (ish) and this may be a simple, long-distance worthy way to get that direct feel. Wouldn’t work so well on MTB if it needed a BB-mount tensioner though, can see that being equivalent to an RD.
(anyone done this and found a good BB mount tension method? I have a fiver on @epicyclo having done it)
Edit, like this > https://clee-cycles.co.uk/P1677/product

they don’t like shifting under heavy load and can slip if you try. Not ideal for a MTB.

If you’re smashing through gears and brute forcing the chain then that’s 100% poor technique, not the fault of the IGH. Learn to change gears smoothly and all drivetrains will improve.

Thols2 understands properly how rear mechs work – saved me some typing 🙂

And if you watch a muddy cross race, you’ll understand how a lot of rear mech failures occur. It isn’t from impact – it is from something in the system getting sticky or jammed and then dragging the mech. So that can be all kinds of things:
Stuck freewheeL
Seized or jammed jockey
Twig
Tight chain link
Bulging open chain link
Chain suck / sticking to the underside of the front ring

I’m commuting 7 miles each way on Alfine. That will change to 20 miles with a house move in summer. Just starting on a new commuter frame which will probably keep the Alf (although I do have a totally inappropriate desire to make a single sided / righty Gates ss frame).

Have a disc mount 135 Sturmey in the attic – weight and efficiency are OK, just a weak axle and non existent sealing stops it getting more use. I did swap some emails with Alan at Sunrace 10yrs ago, but he could never see there being a market for mtb 3 spd.

Love ss and need to go back for mtb duties sometime. I’ve got two drawbacks – slow and cold on long flat / roadrunner sections. And it used to work great riding with the kids, but now eldest is proper u23 xc race fast, I get left behind EVERYWHERE unless the terrain is just right.

Just out to play in the snow so pray for my mech…

@jameso I looked into something similar but at the time couldn’t find a sprung front tensioner that would accommodate the double chainring width.

I never had any of those issues with my alfine. I think much of the issues people get with alfines are due to lack of maintenance.

No problems with high torque – I ran mine at the puffer on stupidly low gearing with no issues

(anyone done this and found a good BB mount tension method?)

Tried a few and not found one I like.
I think the two jockey wheel rear tensioners are a better solution – Rohloff, Paul’s, Alfine are the 3 I can think of.

I never had any of those issues with my alfine. I think much of the issues people get with alfines are due to lack of maintenance.

No problems with high torque – I ran mine at the puffer on stupidly low gearing with no issues

I ran mine with a 30 front and 22 rear. Way outside the recommended gearing.

Gave it an oil dip once a year, and it ran fine.
It did eventually die catastrophically, but it gave good service while it was alive!
Considering I bought it for £100 second hand and ran it for 5-6 years I was happy.

I think the two jockey wheel rear tensioners are a better solution – Rohloff, Paul’s, Alfine are the 3 I can think of.

They would be better/easier, I suppose visually I’m after a clean rear wheel and dropout area and moving the mechanicals to the chainset. A bit like a 30s Bianchi.

I think my puffer gearing was 26 front and 22 rear. Might have been lower.

Also don’t forget running costs are virtually zero with an IGH

I think much of the issues people get with alfines are due to lack of maintenance.

So, are they low maintenance or high maintenance? 🙂

I think my puffer gearing was 26 front and 22 rear. Might have been lower.

😲 Impressively low!

So, are they low maintenance or high maintenance?

If you’re happy taking out the internals once a year to dip in oil, then I’d say low maintenance.
Some people wouldn’t like it though. Involves cone spanners and ball bearings.

Low maintenance – annual dip in atf. Takes about 20 mins plus a while sitting in the bath 🙂
Edit – a single cheap chainring and a single cheap rear sprocket – and they last much much longer. I also like the silent running.
I also have a rohloff and a SA 3spd

MY puffer gearing effectively worked out similar to a 9 spd 2x setup but only the granny ring ratios. span out about 12 mph

jameso
anyone done this and found a good BB mount tension method? I have a fiver on @epicyclo having done it

You’re right.

About 22 years ago. The BB mount tensioners were enjoying some popularity amongst the DH crowd in my area and I saw it as a possible solution to tensioning a SS chain on an MTB frame with vertical dropouts. (For some reason they weren’t making MTB frames with proper dropouts back then 🙂 )

The drawback I found was that I could make it slip out of adjustment under pressure. I didn’t persevere with it because a frame with proper dropouts came on the market so I imported that (thanks to Surly for the 1×1, still riding it).

I reckon it would work better if the tensioner had a spring mount. Alternatively a bike frame the ISG mounts on the BB shell rather than rely on the clamping action of the BB against the shell.

My solution was Magic Ratio. It works pretty well, all you need is three cogs, one on each side of your ideal. Even better if you want to fine tune is a couple of chainrings, eg 33 and 32. That way, you’ll find a combo that works and isn’t too tight or too slack. I use steel chainrings to avoid wear. A properly set up SS chain can tolerate a lot of slack so wear isn’t a problem (especially with steel rings).

Always remembering, it’s not worth obsessing about getting the perfect ratio in SS, close enough is good enough. We’re in the wrong gear 90% of the time anyway. 🙂

I’ve also got a Nuvunci hub that I’ve experimented with on my Krampus.

460% gearing, continuously variable gearing via a twist grip.
It’s a great concept, but…
a) very heavy.
b) very draggy in the lower gears.

My fiver was safe : )

I reckon it would work better if the tensioner had a spring mount.

That’s it, something like the Yess tensioner I found with a mod so the roller/JW could slide to account for 2 rings with a 10-12T gap. Might be a DIY job for the new year, got a load of old DH BB mount stuff that may help. The 2 rings + FD with SS rear idea appeals and could make a nice bike.

my eyes!

Tom – spare alfine hub sitting in my garage with all the kit doing nothing. open to offers… 😉

weight in the wrong place for MTB IMO.

So just like all normal gears have their weight in the wrong place then?
https://singletrackworld.com/forum/topic/stu-mcgroos-lets-put-this-alfine-weight-issue-to-bed-once-and-for-all-thread/

@Del
I’m running out of bikes an Alfine will fit on.
Of the bikes I’d want it on only the Krampus doesn’t have a thru axle.

epicyclo you originally said

Derailleurs … hang where they get a continuous spray of grinding compound aka mud, so drivetrains are regarded as consumables these days.

Implying that your non derailleur bikes don’t hence my previous comment.

I ran mine at the puffer on stupidly low gearing with no issues

Not meant at all personally tj but there are no climbs there that are even remotely steep, so I can’t see that as high torque for the hub.

Otherwise I quite like the idea of fewer gears with bigger jumps, so many benefits, and unless you are racing you don’t need to be in the perfect gear IMO.

@jameso ah, using a 2x!

how would you feel about the return of the hammerschmidt or something similar?

this always seemed like a good idea. would be good with smaller cassettes and wider flanges.

I found the chainstay mounted Suntour mech that removes a bit of the clutter behind the axle. Even has the indexing in the mech not lever.

http://www.disraeligears.co.uk/Site/SunTour_S-1_derailleur_S100.html

Alfines don’t shift under load, but they do keep going in your existing gear without complaining (the shift just happens once unloaded).

@mick_r
Interesting website. This page says that Shimano started out making derailleurs then switched to hub gears, then went back to derailleurs to increase the range of the hub gears, then started selling derailleurs as a stand alone product. It was the Tourney that conquered the world, introduced in 1967 as the Skylark.

http://www.disraeligears.co.uk/Site/Shimano_derailleurs.html

Not meant at all personally tj but there are no climbs there that are even remotely steep, so I can’t see that as high torque for the hub.

its the overall gearing you run that effects the torque thru the hub – not the steepness of the climbs

far too exposed for UK mtb conditions unless you stick to the manmade mtb trails.

This is just click-bait crap, and you know it. if you want to have a discussion about gears, go for it, but like Daffy in 30 years + of riding everywhere, from the alps to Moab, from the Chilterns to Calderdale and Scotland I’ve never bust a mech, so I guess any issues you have with them is user failure.

I do I usually pass one poor soul every lap with a busted derailleur

Anecdote is not evidence.

Derailleurs are a well perfected mechanism for efficiency, so I don’t see them replaced by an alternative system

Rohloff have been doing nothing but trying to develop a hub gear for 25 years now, it’s still too heavy, too complex and not user serviceable. It’s totally unfit for purpose. If hub gears, like other forms of front suspension were going to replace what’s there already, it would’ve happened. It hasn’t because:  Le mieux est l’enemi de bien (as Voltaire probably didn’t say)

but they hang where they get a continuous spray of grinding compound aka mud, so drive-trains are regarded as consumables these days.

Everything from the chain to any gear system you put on the back of a bike is going to get covered in spray…(correlation is not causation)

The manufacturers benefit from their systems being consumable, so there’s no motivation to change to something more durable.

That’s because derailleurs are durable, I’ve never bought a mech. to replace a broken one, and that’s the experience of most folk. That you ride with folk who’ve broken them is conformation bias, there are millions; literally millions of mechs in the world being perfectly happy

What improvements to the derailleur can STW come up with?

Teaching people how to ride? your issues with them are clearly user based..You trot out your personal ennui every few months Come up with something else to grumble about, (old men, sky, shouting etc etc)

Rohloff have been doing nothing but trying to develop a hub gear for 25 years now, it’s still too heavy, too complex and not user serviceable.

If you browse about that website that mick_r linked to, it says that Shimano started out making derailleurs then introduced hub gears (for commuter bikes) and stopped making derailleurs. Then they started making derailleurs again and dominated the market because they made an affordable, reliable derailleur for touring and commuter bikes. This goes back far before Rohloff, and hub gears have long had a solid niche market, but derailleurs are simple and cheap to manufacture and are good enough for most people. I’ve bent a couple of derailleur hangers and destroyed one derailleur in 20 years. It’s so infrequent that it’s not a big problem.

I’ll not be buying a Rohloff, but the “not user serviceable / unfit for purpose” is stretching things a bit far. Do you do much servicing of your car gearbox? I used to have a fun leg-pull with an old engineer at work who was a Sherpa van fan whilst I ran fwd Citroën vans:
Q “How do you easily reshim the differential on your fwd French cr@p?”

A “In hundreds of thousands of miles the diffs have never needed reshimming….”

Ironically he now owns a VW T5, one of the fwd vans most prone to diff / driveshaft issues 🙂

How about a non-epicyclic hub gear? Pear shaped flanges with multiple spoke lengths would be fun…..

I’d like to see more development of a 5 to 7 speed systems, IGH or derailleur. Wide-ish ratio, bigger jumps accepted. Chain durability and general tolerances increased. Longer wear rates.

I wholeheartedly agree. The whole “progression” being based on number of gears causes compromises elsewhere.

It’s a bit like all new cars having to having to have 24 valves or 7 seats just because they can.

There’s a definite need for a rock solid and quality 7 speed system. I’d even like to see a modern version of a 3 speed wide range hub gear.

We’ve already got rid of 3x and 2x is going….

PS. I like gears!

PPS. A big issue with having bombproof derailleurs is that when they get a clang the frame can end up taking the brunt of it…

but the “not user serviceable / unfit for purpose” is stretching things a bit far.

Rohloff insist on servicing their hubs*, there are no user serviceable parts and going through hub deep water is “extreme conditions” as per their warranty…SFB, (recently departed of this forum) had to send a hub back to Germany twice after some river crossings in the Lake district. They admitted to him that it wasn’t sealed well enough not to ship water and fail. For an apparently off-road suitable product that for me falls into “unfit for purpose”. My derailleur has never failed to work because it’s got wet…

* and you need to ship it there at your own cost…Good luck with that now we’re out of the EU.

While everyone here is waiving their penis around telling each other they are wrong, I’d just like more choice.

I don’t care if rear mechs are prone to smashing or hubs feel like riding through treacle, I’d just like a bit more variety and choice when it comes to the bit between pedals and rear wheel.

its the overall gearing you run that effects the torque thru the hub – not the steepness of the climbs

It’s both and also how much W you put through the hub.

I still dont see the Puffer as a reliable test.

I’d just like a bit more variety and choice when it comes to the bit between pedals and rear wheel.

Basically this.

The whole “progression” being based on number of gears causes compromises elsewhere.

All engineering involves compromises. A 7 speed cassette cannot have the range of a 12 speed without having much larger gaps between the ratios, so engineers have to decide which compromise is better. A 3×7 system would allow a stronger rear wheel and give good range with small gaps between ratios, but having a front derailleur is a compromise. 29″ wheels have benefits over 26″ wheels, but they are difficult to package with a front derailleur, so 1×12 provides a better gear range than 1×7 would without needing huge gaps between ratios. Any choices you make like this involve compromises, with cost being a major one. There’s no point making the best system in the world if nobody can afford it.

A light-ish 3 speed hub would be lovely please.

A 7 speed cassette cannot have the range of a 12 speed without having much larger gaps between the ratios

For a lot of people that’d be ok, I reckon. Maybe even 5 speed would be ok. Like, if I’ve got gears on my bike I’ll tend to leave it (10sp) in 7th which in my case is a singlespeedy sort of gear and maybe wiffle up or down a gear depending on what the road or path’s doing or I’ll just dump it right down to the bottom gear if I’m knackered (or get off and push!)

There’s a definite need for a rock solid and quality 7 speed system.

Really? Surely 11sp is rock solid and quality?

Based on only my experience, a nice 5-7 speed would suit ebikes. Think the last one I borrowed I only used 3.

@Jameso I used that Jones mod for years, originally with an XT 34t cassette and an old Shimano 600 derailleur then found Sunrise do a wide range 8sp cassette which when split and replaced, gives you 13-34 or 15-40. The cogs are even 10sp width, so could probably be spaced 7 at 10sp spacing.
I’ve recently gotten a modern bike with SX and I’m seriously unimpressed with it, which may be me, mud or general wintryness.

Really? Surely 11sp is rock solid and quality?

And 12 sp. to be fair, mines be totally reliable (as was the 7, 8, 9, 10, and 11 speed that proceeded it)