Ohm

Hi all you tandem enthusiasts!
I'm new to this forum, having found it a week ago when trying to catch up on what have happened the last 10 years in the world of tandem bikes... I must say that I have found a a lot of interesting information in this departement.

Circa 93 I bought a 26'' Burley Rock'n roll tandem together with a friend. It had rather cheap Suntour/Sugino components, brakes, rear and front mechs, hubs, and cranks. We used it very little as it was very difficult to ride off road.

1:st rebuild after 2 years; Mavic rear mech, XC pro front mech, XT thumb shifters, XT 8 speed hubs (bolt on rear), Mavic 117 SUP/DT 14G brass nipples, XC pro brakes, XT brake handles, Scott AT4(?) bar, chrome Tange big fork, ligher stem etc. I used this setup for one longer touring vacation without any problems at all.

2:st rebuild 3 weeks ago; new crank setup - se pics from my workshop.
I have used this setup for a week of touring around Denmark without any problems but heavy showers...

My questions
1. I'm going to get me a new rear wheel - what rim, hub, spokes should I buy in order to get the strongest ones?
2. What do you think of my 'right-timing' setup, I'm thinking about getting new cranks - any ideas?

//Thanks in advance!



rear crank Suntour XC comp110/74 mm 50/40 Sugino / 32 TA, front crank LX 94/58 mm 32T TA ring

masiman

I think that is pretty interesting to set up your timing chain that way but I am guessing you are sacrificing your granny gear.

I'll leave it up to others to recommend wheels. I would guess the Velocities would be mentioned.

That rear triangle is interesting looking too. I guess to make it a little more comfortable for the stoker?

SDS

I don't like "right-timing" with small rings. Reason: the smaller rings make the captain cranks mushy because they give the crankarm greater leverage to wind up the chain and flex the bottom tube. Most modern tandem cranksets have 40T timing rings. I use 50T.

zonatandem

Burley's rear triangle arrangement was standard for them at that time as was the componentry.
Asides of giving up granny chainring with same-side-drive, you may be contributing to the flexier feel. If you are living in 'flat terrian' you may not see a need for a triple setup.
Does not look like original paintjob . . . but looks great for a '93!
Rear wheel suggestion: Hub by Phil Wood 36 to 40H; rim Sun Rhino, double butted spokes by DT or Sapim.

TandemGeek

Wheels: What's the problem with your current rear wheel? Assuming it needs to be replaced, what's the total weight of your team and do you carry anything else on the bike? What size tire do you plan to use on your tandem?

Same-Side Drive / New Cranks: If same-side works for you, then it's a good choice. That said, what do you hope to accomplish with new cranks and what do you have in mind for the bottom brackets?

mrfish

Agree with TG, if your cranks are the right length and q-factor for you, there's not much to be gained by changing them.

Stiffness, weight and aesthetics perhaps can be improved perhaps by an upgrade, but in the end mid range / expensive cranks doen't really make much difference to performance, other than in front shifting - my Dura Ace rings on my single bike shift better than my mid range campag ones. You will probably find that the shifting is improved if you get a new crankset, but otherwise it's marginal. That said, a single-sided Dura Ace / XTR / Record Carbon triple setup would look nice IMO, and be suitably wallet-busting!

Ohm

My idea was that the 'straight' route between the front chainring and the cogs should decrease the mushy feel at the captains pedals, weigh less and look good, but I didn't think about the negative effect of having a small ring - other than the increased wear... Hmm, have any of you compared with and without a 'right-timing' chain?

Theoretically; I have decreased the distance (shorter bb axle) between bottom tube center and chainring center by a 1/3 (leverage) but I have also increased the force acting upon this lever by 1,56 (50T/32T) which should give the same torque (2/3*1,56=1)...


No problems about losing my granny because the southern part of Sweden is very flat.


Thanks, and you are right about the paint - we paid extra for a custom paintjob.


I should look into such a combo hoping to get a most reliable rear wheel. I would love to throw away that standard Shimano ratchet mechanism in order to sleep well on our future trips.


No problems at all, but I'm afraid of the hub freewheeling all of a sudden, or the rim going wobbly. We did carry, and plan to carry a lot of camping and fishing equipment on our trips - maybe I should go for a trailer?
Team weight; 145-150 kg / 320-330 lbs
Tires; 1,5-1,75" semi slicks


I must admit that there IS a a problem with my current setup as the front bb axle is shortened by splitting and then joining the two parts together again, the joint is n o t reliable - shouldn't break in 100,000 years but could quite possible rotate tomorrow morning with the chosen method...

I need a new complete bottom bracket with an axle length of 97 mm (square taper SIS), or new cranks/bb too if I can't get such a short axle. Getting new cranks/bb where the middle ring sits 43 mm (cc) from the down tube shouldn't be to easy either...
And of course... matching cranks in front and in the rear should look way nicer than having a mixed pair... or maybe not - can't decide fully.

Machining of the Burley eccentric, or making a new one in order to fit any new or old bb design shouldn't be any problems as I could get qualified help.


Mmmm, any of those would look nice. Maybe I should go for a pair of used old style square taper XTR cranks, and custom length titanium axles (from where?). My 'help' have already told me not to ask him for a square taper titanium axle although that I do have a suitable high grade (4/6) 1" bar/axle in a box.

TandemGeek

Your older Burley would be a bit more prone to frame deflection than many more contemporary, major brand-name tandem frames as larger diameter, stiffer tubesets are used for the boom tube and elsewhere in the frames. However, unless you find your tandem is ghost-shifting under heavy pedal loads or throwing the timing chain, the frame deflection is nothing I'd lose sleep over. It could also be an issue if you're trying to shave a few ticks off the clock on your time trial times as it's conceivable that you could be losing some efficiency, but that too seems to be a non-issue for you (and most every other tandem team). Of course, if you've got any significant frame wind-up chances are the rest of your frame isn't all that efficient either: again, if you're not racing and the tandem otherwise meets your needs and expectations who cares.

As a rough gauge of how much deflection may be occuring, ask a riding mate to look at your timing chain when you're pedaling under a heavy load and let you know how much it's sagging compared to when your tandem is at rest. A certain amount of the sag comes from the chain going into tension but excessive difference between how much a timing chain sags when static versus under load does suggest there's some frame deflection going on.

It appears as though you're still running the original 7 speed Shimano HF05 (STX/LX) tandem hub which, admittedly, isn't top-shelf. They were more than adequate with 12x28t cassettes, but the 34t models were the kiss of death for larger teams using the HF05, as well as the 8 speed Shimano HF07 (STX/LX). Shimano solved it's tandem hub durability issues when they introduced the [Delete] HF08 (XT) grade 8/9 speed hubs which remain one of the best-value tandem hubs you can get. They're not sexy, but they are durable... so much so that Tandems East and others use them as the standard hub on their tripets and quads. In fact, the internals of the HF08 are what Shimano uses for the hub of their Shimano/Santana Sweet 16 tandem wheelsets and I believe they are still what you'll find inside Shimano's XT hubs. So, my point in running through all of this history is to suggest that if you have concerns about your rear hub and the rim is otherwise still in good shape you merely have the wheel rebuilt, perhaps with new spokes, using the HF08 and also upgrade your shifter and derailleur to 8 or 9 speed at the same time... the latter readily available second hand or for not a lot of $$.

Not sure I fully understand what has been split and welded -- the axle? -- but given that you're using a right-side drive any standard MTB square taper (JIS) crankset will work; choose your finish to match or contrast with your rear cranks which can also use standard MTB models. I'll leave the re-engineering of your front BB to you and your helper. While 97mm is ideal, you could go wider if needed so long as you don't create an interference problem between the timing chain and the chain on your middle ring.

Ohm

TandemGeek:
I do have XT 8 speed hubs but they have no cartridge bearings inside, are you talking about some special 'tandem' XT hub?
cassette; DA 12x23
shifters; XT 7 sp thumbshifters used as 8 sp

What about this hub for a a new rear wheel?
https://www.winstanleysbikes.co.uk/in...=5465&brandID=

Yes, the front BB axle is splitted, shortened and then joined together - no good idea

I have decided to keep my wallet fairly closed regarding cranks as I have found a pair of Dura Ace cranks (old squary ones, ca 92??) among my stuff. But that's not all, as I also found a nearly unused Hope titanium bottom bracket with a suitable axle length.

I'm going to machine a new excenter with threads for my Hope BB, but the rear axle length seems ok for my DA cranks so I don't have to change that one too. I'm going for a pair of new 39T synch rings.

Ohm

I mean this hub; Gusset Jury Hub

TandemGeek

I had a brain f*rt: HF08 use conventional ball bearings, cups, and races. The only difference between the XT and tandem hubs are the hub bodies (taller flanges with 40h & 48h drillings) and the longer axles: the guts are the same.

Ohm

TandemGeek; My XT 8 sp hubs are quite good you say, so there's no idea going for something else - for example a 'Gusset Jury' rear hub? Is PW hubs the best out there?

Thanks for helping me out!

TandemGeek

If they are the HF08 model, then yes... they are very durable.

As for the Gusset Jury, at 650 grams it sounds like it has some beefy guts to it. However, before buying one I'd sure want to ask the manufacturer if it they'd warranty it for use on a tandem.

As for the "best" tandem hub... Phil Woods are excellent hubs. But so are Chris King's and several other less expensive brands and models. In other words, I personally don't believe a Shimano hub is any more prone to problems than the PW or CK hubs under most conditions, but they certainly don't have the finish or panache of the PW and CK hubs. For the ultimate in "bomb-proof" design, CK is the pick of the litter for off-road tandems if only because Phil Wood has never developed a better seal for their tandem hubs.

So, from a value perspective, the "best" tandem hub could be quite different from the "best" overall in terms of how consumers view the hub or with respect to what you're doing to the hub. White Industries tandem hubs seem to fall somewhere in between the two ends of the spectrum: good looking, durable, and moderately priced.