Rear hub choice for heavy touring tandem with Arai brake

[mumford]

Hi all,
Kirsty and I are 12 weeks and 6000km into a 2 year tour from the UK to NZ on a Thorn Discovery tandem. Www.shesnotpedallingontheback.com.

We bought the bike second hand a couple of years ago so have no idea exactly how many miles it's done but the previous owner thought it was built circa year 2000 and they'd done some shorter trips. We've put a few thousand km onto it before starting this trip too.

Before we left we had the hub, a 48h Shimano tandem unit with Arai drum, serviced but it developed a bit of play about 5000km into this trip. We had it stripped and regressed and new seals fitted and all seems to be OK for now but for how long? My worry is that it may not be reliable through the tougher parts of the trip like The Pamir highway, Nepal and China. Parts may be harder to find over there too.
Has anyone any experience of this hub for long tours? Should we just be prepared to service it every few thousand km and cast spare parts? The alternative options seem to be a white industries or remortgage for a Phil Wood and get the wheel rebuilt. If this means a more bombproof solution and some peace of mind then it could be worth it.

All thoughts, suggestions and stories of experience would be appreciated.

Regards

Marcus

[Danneaux]

Hi Marcus, and welcome to the Thorn Cycling Forum!

I'm in a similar boat with my 1989 tandem and Arai drum brake. I know eventually the Suzue freewheel hub will need replacement and then...? Some of the newer tandem rear hubs with threads on the left side are indeed incredibly expensive.

For awhile, I was in negotiations to have an adapter made to go from a 6-bolt disc hub to a threaded Arai mount. Things looked promising for awhile, but fell through. I'm now looking at the problem anew and wondering if the Arai's backplate could be modified for a 6-bolt disc hub. I've found the Arai to be really helpful on long, steep descents. With its SunTour bar-con actuator at full lock as a drag brake, it keeps the speed down to around 68kph/42mph. Without it, I commonly hit speeds over 101kph/63mph with a stoker aboard on the steep hills surrounding Eugene on three sides. I use SunTour and Scott/Pedersen SE cantilevers along with the Arai. Drums can absorb a *lot* of heat and still work well. I've seen mine glow quietly after long nighttime descents.

Past post on the topic here: http://www.thorncycles.co.uk/forums/index.php?topic=7115.0

Of course, Arai is no longer. An (expensive) replacement is now available in the Maddock Machine "Mad Dog" drag brake, manufactured just up the river from my home:
http://tandemgeek.wordpress.com/2010/11/14/next-generation-drag-brake/
http://tandemgeek.wordpress.com/2013/07/10/next-generation-drag-brake-now-available/
http://www.tandemseast.com/parts/brakes.html#Maddox drum

Back to hubs: Here's a list of cassette hubs that are currently available *and* Arai-compatible:

• Phil Wood (40, 48 drillings)
• Shimano (HF-07 and -08 in 145 and 160 OLN, 40, 48 drillings)
• White Insustries (Daisy and Jockey models, 40, 48 drillings)
• Hadley (40, 48 drillings)
• Aerospoke 26in tandem wheels can be had in a model that is Arai-compatible
• Chris King (maybe, made in Portland just north of me)
• DT Hugi (maybe)

What I'll probably do with the Suzue is use it till the ball races are gone, then knock out the ball race and mill the opening to take a sealed cartridge bearing and press that into place. Should work so long as my stock of 7-sp SunTour AccuShift freewheels holds out. A lot cheaper than buying one of the options above, though it is really just postponing the inevitable.

Given the costs involved, if I were in your position at present, I'd lay in a stock of spares for the Shimano and figure on it raking me through the Pamir and beyond if serviced periodically. Remember, the right-hand bearings are in the freewheel part of the freehub, and the left side has adjustable cones. Therefore, the thing to ultimately limit you would the be the condition of the left bearing race, and it could be milled and replaced with a sealed cartridge bearing as I plan. I've done it once before on a single-bike hub with good results.

If you do go with a replacement, I think I'd choose the Phil FSA (Field-Serviceable Axle) Arai-compatible tandem hub, and take a spair pair of bearings with me in case field-servicing is needed.

In case you're wondering about the other side of the equation, Arai brakes can be relined at any friction materials shop (automotive clutches, brakes) and I once knew of several moped brake shoes that would fit reasonably well with a bit of edge grinding. be sure to grease the cam actuator with just a dab of high-temperature brake grease that won't run when hot, and replace the friction materials before the wear goes into the shoe itself.

Best,

Dan. (...who would rather his tandem brake than break)

[il padrone]

As far as I am aware all the Shimano hubs run with standard cup & cone bearings. I don't know why you would want to move from ths to sealed cartridges on a global tour as bearings (and probably cones) for these are going to be far more readily availble in places like Kashgar than sealed bearings to fit a specific bicycle brand.

"developed a bit of play" Normal treatment for this would be a quick and simple cone adjustment and set, rather than a strip and regrease. Was there some other concern that prompted this? BTW, always go with loose balls with a cup & cone, not the caged balls.

I have the Shimano HF08 hub on my tandem with an Arai brake fitted. It has been fine, but has not done too many thousands of kilometres so far. My old Sedona MTB had Sunshine hubs, with cup & cone bearings and simple rubber contact seals on them. These hubs were seriously neglected   They ran for 20 years, probably something over 100,000 kms, just retired off what is now my son's bike last year for the Rohloff, and in that time they were probably only serviced about four times.

I'd be really surprised if you continued to need hub servicing every few thousand kms.

[Danneaux]

I don't know why you would want to move from ths to sealed cartridges on a global tour as bearings (and probably cones) for these are going to be far more readily availble in places like Kashgar than sealed bearings to fit a specific bicycle brand.

Well, Pete, ball-bearings are indeed likely to be available in many places. However, that is not always the case for cones, which can become pitted and -- eventually -- races, which can do the same. I've had a tough time over the years finding cones for my older hubs right here in Civilization. They key problem I've found has been the thickness of the cones, their outside diameter at the hub dust cap or seal, and the angle of the bearing-race, making for something less than universal substitutions. Thank goodness for Wheels Mfg and their stock of parts available to nearly any bike shop who orders from them: http://wheelsmfg.com/products/axles-cones-hub-parts.html

If sealed bearings are user-replaceable and a person packs a pair in their kit, the entire hub can made essentially new just by swapping in a fresh set. They typically require no maintenance, but it is easy to remove the seals with the tip of a Swiss Army Knife, flush with solvent and regrease if water does get inside. Most are standard sizes available in advance from nearly any industrial bearing supplier. A pair doesn't take up much space in a touring spares kit.

All the best,

Dan. (...who thinks such matters are of great bearing for the touring cyclist )

[mumford]

Thanks for the advice guys. I think I'll get down to Athens and then open it up again and see what condition the cones and bearings are in and if needs be replace them there. It should be relatively easy to find the parts there  (hopefully). I think carrying spares for the rest of the journey is then the best and of coursr cheapest option. But if it continues to be a problem we have a stopover with friends in Baku so could get a new hub sent there. This would set us up nicely for the Pamir.
As for the full strip down rather than adjusting, I didn't have much choice as the bike shop we took it to in Ukraine insisted on going it for us, right there on the pavement!

The joys of touring, always something to worry about!

Thanks again and happy pedalling.

[Danneaux]

Happy, safe travels, Marcus; may your trip be full of only the "right" kinds of Adventure!

All the best,

Dan.

[mumford]

So I've finally got round to opening up the hub after a lengthy search for new cones and bearings (I think I found the last two sets in the whole of the UK and got them shipped to Greece!). Its not a pretty sight though (see attached). The drive side is heavily pitted, the bearings were in a terrible state and the cone has begun disintegrating.

With the new parts fitted I have two options:
Tighten it so that there is no play but it feels a bit stiff and you're can feel a slight grinding on the beating surface. Or allow a tiny amount of play so that it runs smooth.
I've opted for the latter but suspect it'll loosen up more quickly so will require some frequent care and attention.
With another set of cones and bearings on standby the hope is we should be OK for a good free thousand kms yet but we'll have to wait and see.
is there anything that can be done to revive a pitted hub?

[Danneaux]

is there anything that can be done to revive a pitted hub?

In this case, the answer is "Yes, perhaps".

On a freehub, the right-side bearing race is contained in the freehub body. If you can find a replacement freehub body, it can be screwed onto your hub and the wheel would not even need to be rebuilt. SJS Cycles has some. See: http://www.sjscycles.co.uk/page/find/?geoc=us&name=freehub%20body&page=1

Cassette-side bearings wear more because they are under higher loads from drive torque, especially on a tandem. Replacing the freehub body should see you good to go.

Best,

Dan.

[mumford]

Ah yes, of course! That's great news thanks Dan. Hopefully there won't be too much damage to the new bearings before I can fit a new freehub. Also need to find a free hub from somewhere... I'm sure there will be one in Istanbul though.

[Jack_Luke]

For awhile, I was in negotiations to have an adapter made to go from a 6-bolt disc hub to a threaded Arai mount. Things looked promising for awhile, but fell through. I'm now looking at the problem anew and wondering if the Arai's backplate could be modified for a 6-bolt disc hub. I've found the Arai to be really helpful on long, steep descents. With its SunTour bar-con actuator at full lock as a drag brake, it keeps the speed down to around 68kph/42mph. Without it, I commonly hit speeds over 101kph/63mph with a stoker aboard on the steep hills surrounding Eugene on three sides. I use SunTour and Scott/Pedersen SE cantilevers along with the Arai. Drums can absorb a *lot* of heat and still work well. I've seen mine glow quietly after long nighttime descents.

Hello Dan. Apologies for dredging up such an old thread but I'm keen to hear more about this proposed 6-bolt to Arai thread adaptor.

I'm committed to using an Arai drum brake in the long term (we've only just had our Orbit repainted with the Pac-Man mount intact!). I'm very happy with my DCR Arai-threaded hub, but spares are patchy. The ability to swap to more widely-available hubs would put my weary mind at ease.

The link you have shared no longer works and isn't available on the Wayback Machine. I don't suppose you have any notes, discussion or drawings of the adaptor? It is something I would consider having made one-off, if so.

[Danneaux]

Hi Jack!

It has indeed been awhile, but the problem is still present for those of us with tandems running the once ubiquitous combo of Arai drum-drag brakes on double-threaded freewheel hubs.

I solved the problem most quickly by finding a lightly used Sanshin double-threaded rear hub already fitted with an Arai backing plate (the portion with the heat-sink fins and steel drum insert). That gives me a hedge against wear and further obsolescence, so I backed off the quest to have an adapter milled.

There's a growing number of CNC operators online who will mill or laser cut whatever you need from CNC files forwarded to them. SendCutSend is one such firm...
https://www.facebook.com/sendcutsend
https://sendcutsend.com/?fbclid=IwAR1SRD20j_QWcuYpytN6_bx-prAO8m1l3MFlV6VdG95mrjL-YrS85iiszzI

If you Google "Free CNC software" (no quotes), you'll find a number of sources for creating your own CNC files without having to spend money on an app/program.
=====
In the last year or so, a number of freewheel thread-to-6-bolt adapters have become available. One reasonably priced example here...
https://sendcutsend.com/?fbclid=IwAR1SRD20j_QWcuYpytN6_bx-prAO8m1l3MFlV6VdG95mrjL-YrS85iiszzI
...that would allow one to substitute a disc for the Arai drum brake, but this does no good if you can't source a reasonably priced double-threaded freewheel.
=====
BMX double-threaded hubs are a possibility, but the threaded portions on the ones I checked appear to run a bit short for multi-speed freewheels, being intended for single-speed freewheels. A flip-flob fixed-free hub won't work because the fixed side has double lands to accept a lockring.
=====
I just dashed out to the garage and took another look at my spare Sanshin hub with Arai backing plate. Provided you could drill accurately and concentrically*, I think it would be possible to use the Arai on a 6-bolt rear hub. When I have a little free time, I may give it a go. There appears to be enough clearance for bolt heads inside the backing plate without fouling the brake shoes and actuating mechanism. I may give that a go, as I am unlikely to need the spare backing plate as-is and I don't see a problem if it has holes as I can always plug them if unused. Chainring spacers could be used for lateral adjustment, leaving the only concern being if the drum was spaced too far left for the fins to clear the stays. A disc freehub would have far better support for the rear axle than the present freewheel hub and would go far toward eliminating the occasional bent rear axle, so the idea appeals beyond just greater availability. If you have not disassembled your Arai for a look-see, this link with photos of the innards might be helpful...
https://www.precisiontandems.com/arai.htm

*To mark the backing plate concentrically, I'd simply disassemble the Arai, then mount the backing plate reversed, so it was inside-out, place the wheel in my truing stand, spin it, and hold a carbide scribe against the backing plate at the prescribed BCD to make a bright ring in the black finish, then drill on that line as a center using a template for bolt spacing.

Best, Dan.

[Danneaux]

FYI, Jack, I just made a quick check of the Arai backing plate, the finned aluminum drum that screws onto the left-side hub threads.

• Without removing it from the hub, inner diameter of the threaded mounting hole in the backing plate is nearly 35mm ID (1.37in/34.79mm)
• The big nut cast into the backing plate has 41mm flats, same size as the socket needed to unscrew it.
• That nut measures 44mm diagonally across the rounded points
• Standard ISO disc-mounting BCD is 45mm
• Standard ISO disc-mounting bolts are M5x0.8 x 10mm T-25 heads, would need to be longer to go through the Arai's thicker backing plate and then far enough into a hub's threaded disc mounts. I'd resist the urge to use allenhead bolts as they don't do so well in this size at the required torque. I'd use threadlocking compound, too as you wouldn't want the drum coming loose. In its native application, braking screws it tighter onto the hub and that failsafe won't be in place if mounted with bolts.

I would drill from the flat back side, as the screw heads will impinge on that big hex nut. The holes will need to be relieved on the inside of the drum to provide lands for the T-25 heads. I'd take another look before starting to see if it was better to drill the holes centered on the flats or the points of the nut.

I'm intrigued. When I can find time I may give it a go myself, as it would be nice to have a fallback option for my spare backing plate and I am pretty sure it could still be used as originally intended if necessary. The one sticking point is axle length. It can be difficult to find axles for OLN dropout spacing wider than 135mm.

Best, Dan.