SRAM dualdrive - experiences of?

[Wombat]

Being a recently retired and desperately unfit old git who currently hardly rides his bike (Dahon Jetstream P8) 'cos I don't like the roads and their users round here, who is about to retire to rural Wales...

I am seriously tempted to treat myself to that Moulton TSR27 I'd dreamed of for some years.  It seems that Moulton have actually discontinued it, but AVC are game to build one for me as long as they can actually get hold of a SRAM dualdrive hub.  I will desperately need a very wide gear range, and the ability of the dual drive to make big downward drops in ratio in extremis (or where I've suddenly had to stop and was unprepared for it) seems good to me.

Has anyone here had an actual user experience of them, re: ease of use, reliability, etc.?  I could get an different model with a Shimano Alfine  11 speed hub, but I am somewhat unclear as to what the ratios end up as, in ye olde gear inches, on 20 inch (406) wheels.  Unhelpfully AVC's website doesn't tell you that.  I'll be visiting them next week, to have a try of a different TSR, just to check I'm OK with it, so I will firmly make this point, as how on earth can I choose a gearing system when I don't know the ratios it gives?

Only trouble with letting them custom build one for me, I will get the temptation to upspec a few components here and there...

[Auntie Helen]

My partner has a dual drive on his trike and has found it very easy and reliable, although it has got to the slightly noisy stage. They are very common in Germany where all gears seem to be in the wheel and they often just have a single chainring up front (with trikes anyway).

They are relatively cheap bits of kit so are known to need a bit of servicing now and then, but this is generally after 10,000km or so. Basically the thing works fine, from what I can see.

[Tigerbiten]

I thought of getting one when I spected my trike.
But even with a triple on the front I couldn't get the range I wanted.
That's one of the reason I went with a Schlumpf HSD-Rohloff combo.

I'm sure Cycleman runs one on the back of his bent trike.
And gets on with it well ...... 

[CAMRAMan]

I have had a few bikes with the set up on them. It works well, IME, being especially useful when you come to a stop and can change down using the hub gear to start off in a lower gear. The clickbox needs some protection as it does protrude from the hub, but it's fairly robust. The latest one, my Birdy Blue, has it and it's fine.

One worthwhile option is to have the dual controls on one changer. I'm not sure if the twin changers is even an option any more.

[LittleWheelsandBig]

SRAM has stopped making the DualDrive hub but Sturmey are still doing something similar.

https://www.sjscycles.co.uk/hubs-internal-hub-gear-brake/sturmey-archer-rf3-3spd-cassette-hub-36h/

[toontra]

I've just bought a second-hand Airnimal Joey with a 3-speed DualDrive hub & 9-speed cassette.  So far I'm really liking it.  I've always had high regard for SRAM 9-speed stuff so this was one of the deciding factors in buying.

The previous owner said it hadn't been serviced for several years but it runs & changes smoothly - a far nicer experience than any 3-speed derailleur chainset I've ever used.  It also gives a really wide gear ratio - haven't run out on either end yet.

The only thing I need to do now is learn how to get the rear wheel off in case of punctures!

[Wombat]

Thanks for that info, all, and I particularly take note of LW&B's comment that they've stopped making them.  Shame SRAM's website is so hopeless on that front. This would account for Moulton dropping that model, and AVC being vague as to whether or not they could get one (they are checking).  So if they can't find one, its down to an relatively affordable Alfine with a 409% gear range, or a Rohloff at a wallet busting price and some serious issues about building a 406 wheel for it, and its 526%.  I will also investigate the Sturmey option.  Last time I had Sturmey Archer gears was a traditional 4 speed hub gear on an F frame Moulton in the 1960's...

I'm not being dense when I think that if an Alfine is geared so the bottom gear is say 25 inches, then the top would be 102.25, am I?  I suspect a bit of chainwheel jiggling (and ordering special ones) may be called for.  I suspect the Rohloff may be fun with its twin cables, bearing in mind it will be a separable frame...  Looking at the Shimano website, I can only see disc compatible Alfines, not sure I need a rear disc, or even if its feasible with a separable TSR frame.  I've never had a disc braked bike, and I'm still not even totally sure of the advantage of V brakes over calipers, considering how mind-blowingly powerful decent caliper brakes are.  Presumably its about exerting so much pressure that all the crap is forced off the rim, in mucky conditions?

We shall see how it turns out.

[Polar Bear]

I have one sitting in my shed which is I believe unused though the shell is slightly damaged.   I also have the 'two in one' dual drive shifter and the clickbox.

This is for a project that has never seen the light of day so I'd be willing to let it go just to remove clutter.   Buyer beware though as I've never tested it in anger.

[fuaran]

Try Sheldon Brown's gear calculator, it will show what gear inches you can get. It includes the Alfine and DualDrive hubs. https://www.sheldonbrown.com/gear-calc.html

Yes, I think all of the Alfine hubs are disc compatible. But you could build them up with a regular rim (with a braking surface), and use it with rim brakes if you want.

[Brucey]

SRAM announced about three months ago that they are to discontinue all IGHs, and furthermore they are to cease manufacture of spare parts too.  So now would be a strange time to be choosing to buy a SRAM hub if there is an alternative.

FWIW the dualdrive is OK but it has a significant problem; the low gear drive ratchet has been fitted with four pawls in order to reduce backlash.  The pawls engage in pairs and each pair is mounted offset  by a non-integer number of teeth on the ratchet. In this way they have made an 18T ratchet feel like a 36T ratchet (or something), which is all very clever. However they have also doubled the chances of just one pawl engaging too.  Very many dualdrives that are fitted to trikes etc have failed because of this. You can tell if the hub has been doing this or not because the planet cage will merrily be wearing a deep groove in the axle.  Once this behaviour starts (e.g. because the parts are not concentric with one another) it always gets worse.

I have tested a couple of dualdrive hubs and (by rotating the hubshell and the planet cage separately from one another) you can tell that the parts are not made concentric. For example holding the planet cage in one position, and turning the hubshell backwards very slowly, you can hear the low gear ratchet. If the pawls go two at a time simultaneously, you hear a 'cliicckk' sound but if they go separately you will hear 'click-click' instead, which risks one-pawl engagement.  If you then turn the planet cage 180 degrees, it is normal for the ratchet to sound different, indicating that the parts are not concentric.

My suggestion is that if one opposing pair of pawls is removed, there is twice the backlash, but half the likelihood of one-pawl engagement.

The sturmey CS-RF/RK hubs are a suitable alternative but they have their troubles too; the way they have engineered the high gear clutch is unique to that hub type, and seems vulnerable to failure; there are three plunger pawls in the planet cage (which is a riveted, non-serviceable assy) that must all engage with a (non-undercut) six-dog clutch. It seems that the spring on the clutch isn't especially strong and the plunger pawls don't reliably extend if the grease gets a bit sticky. The result is that the high gear clutch can get damaged. Annoyingly whilst SA list all the part numbers to buy separately, you can't buy any separate spare parts for this hub in the UK unless they are also used in other SA hubs. The high gear clutch etc are unique to this hub, so you can't buy them. The next best thing is a complete internal, which is available (at a cost that is not far away from that of a complete hub).

So both hubs are a really good idea but not without their flaws. In fairness on a solo machine with a low all-up wieght the hubs are likely to last reasonably well.

cheers

[zigzag]

i have been using one for about a year, it worked ok, but rattled, was draggy and made the rear wheel heavier than it ought to be. sold it on and used 1x8 gearing instead which i liked much better.

[orienteer]

I have a Rohloff on a Moulton ATB/tandem conversion, with 406 wheels, no problems. By using the optional separate change box at the rear hub, it is easily detached when separating the frame, no cable couplers are needed.

With a 58T chainwheel and (I think) 16T sprocket the gear range is 20 to 105 inches.

[cycleman]

My dual drive is working well at present but I am now going to be worried about finding spares if it does pack up 

[Brucey]

35-406 tyres on Moulton with 44/20 gearing and Alfine 11 hub gives 21.9" to 89.6" gears as per link below

http://www.gear-calculator.com/?GR=SA11&KB=44&RZ=20&UF=1510&TF=90&SL=3.5&UN=MPH

which is oddly enough one option I am currently looking at.

You can select various other hub gears/wheel sizes/sprockets/chainrings via the drop down menus. It isn't quite as versatile as Sheldon's gear calculator (in some respects) but the graphical output is kind of nice.

cheers

[CAMRAMan]

Removing the rear wheel is easy, as the clickbox comes off and goes back on very easily. I think the guidance is to be in hub gear 1 when removing it.

[toontra]

Removing the rear wheel is easy, as the clickbox comes off and goes back on very easily. I think the guidance is to be in hub gear 1 when removing it.

Thanks CAMRAMan - will give it a go.

[LittleWheelsandBig]

SRAM have actually discontinued virtually all internal hub gears, other than 2sp or 3sp hubs.

[Brucey]

SRAM have actually discontinued virtually all internal hub gears, other than 2sp or 3sp hubs.

that was as of a couple of years ago. As noted previously more recently they have discontinued all IGHs and spare parts.  If you buy anything SRAM  IGH now, it will be from remaining stocks.

http://www.bike-eu.com/sales-trends/nieuws/2017/2/sram-stops-remaining-internal-gear-hub-production-10129065

SRAM bought Sachs' IGH division in 1997 and over a relatively short period of time managed to takes annual sales from several million down to an absolutely pitiful 100000.  And recently even the basic three speed hubs have been shite, too.

cheers

[CAMRAMan]

And the Sachs/SRAM Spectro P7 is renowned for being a tough hub able to stand up to lots of abuse. A great pity. I suppose all those hub-geared bikes on sale in Germany will now have Shiimano hubs...?

[LittleWheelsandBig]

Or Sturmey, which are generally cheaper and often lighter.

[Brucey]

And the Sachs/SRAM Spectro P7 is renowned for being a tough hub able to stand up to lots of abuse. A great pity. I suppose all those hub-geared bikes on sale in Germany will now have Shiimano hubs...?

The P7 has not been made for several years (five or more?) and the 'replacement' G8 and G9 hubs were so long coming that most manufacturers had to switch to shimano anyway in the meantime. And to compound this, SRAM stopped the G8 and G9 within about a year of them coming on the market in any numbers

BTW the basic P7 innards are pretty good but the clickbox and the shift rods are (to pinch a phrase from LWaB) truly shitful.  They break, they fill up with water, they generally go wrong too often.  Even when the shifters and clickboxes were more readily available, quite a few users got so cheesed off with it that they insisted that they had a different hub instead, or the LBS condemned the hub as irrevocably jiggered. I've examined about eight or ten such reject hubs and (past a few burrs here and there) there was basically nothing wrong inside.

FWIW (in view of the problems with the clickbox/pushrods and a likely lack of future supply) I am working on a scheme to convert a P7 back to a twin-toggle arrangement, using a RH pull toggle and a LH pushrod.  There will be a three-position shifter on both bars and the shift sequence 1-7 will be (LH/RH);  1/1, 2/1, 3/1, 3/2 (or in fact */2), 3/3, 2/3, 1/3. The hub will default to gear 4 with both cables slack, which is (in contrast to most IGHs) almost sensible....  setting the hub up will be just like setting a 3s hub, twice, i.e. not at all complicated, really.

cheers

[Wombat]

Many thanks for all this useful input!  Sadly I think I've been scared off the SRAM dualdrive (despite PB's brilliant offer), and I think for my particular situation, its probably Alfine for me.  I've tended to believe that anything other than a pure derailleur arrangement was inefficient heavy crap, but with advancing age, I think my priorities have shifted.  I'm game for taking a first stab at gearing with an Alfine, and possibly getting different chainwheels (and new chains) later if the ratio spread is not for me.  I will be pottering along lanes which may be contaminated with sheep shit, so maybe a hub gear is more appropriate than something that hangs its sprockets out in the not-so-fresh air. I will have engineering facilities, and I can't even rule out making my own chainwheels, if I can get hold of details of the relevant geometry of the teeth.  If Shimano suddenly decide to produce a new one with a wider range, then i could possibly afford to change, later on.

All this is in the pursuit of getting me back on a bike in my later years, and trying to avoid the likelihood of getting older fatter and even less fit with advancing age.  Why a Moulton?  I was born and bred on them, and my mum bought me a Moulton Deluxe in 1966 (frame number K66 352914).  I'm open minded enough not to go the "normal default route" of a 700C bike, and tend to consider the Moulton design as eminently sensible.

[Brucey]

it is worth noting that the Alfine system is intended to be used with a tensioner and multiple chainwheels if the number/range of gears using the hub alone is not sufficient. Shimano make all the required parts to implement this kind of setup. Unfortunately the hubs themselves don't accept more than one sprocket at a time, which (if it were otherwise) would be an easy route to more gears too.

cheers

[LittleWheelsandBig]

HK is very happy with the Alfine 11 hub on her wet-weather MTB commuter. Though her space-frame Moulton is 3 x 10 Campag derailleur, I have a Mk3 Moulton frame and a Alfine 8 hub to build up into a bulletproof travel bike. She keeps hoping for me modding it with a separable frame and belt drive but that sounds like putting a lot of money into a fairly gaspipe frame, beyond the already-necessary mods to the rear triangle, forks and BB shell.

Didn't Cyclo used to offer brazed-together SA cogs in the dim, distant past, kind of like a Dingle? It might be fun to similarly braze a couple of cogs together, if sufficient clearances can be maintained.

[CAMRAMan]

FWIW, my experience of the Alfine 8-speed hub is very positive.