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that's simply amazing.
Could you run the timing chain on a pair of granny rings, and shift your 2 main rings out?
neil - Googled Thorn Tandem but so far can't find a pic. of their set-up. I should mention that initially I did get some chain conflict / interference between the timing chain and rear drive chain when on the smallest cassette cogs. I cured this by grinding the mounting points of the rear timing chainring so that it sits a few mm closer to the crank arm.
My partner actually has more torque than me, she does 50 lengths breastroke several times a week at the local pool.
ir_bandito - the problem with that is we definately need the granny on our final-drive for the hills around here. I even converted our nine speed cassette to compensate for the gearing change caused by using 29er wheels. - i.e use a worn (for the purpose of re-cycling) 11-34t cassette where the chain slips on the two smaller cogs - place a single 36t cog on the freewheel - spacer ring - now place on the main xt or xtr cassette body - throw away the two smaller worn 11t & 13t cogs and now place a new 13t 'end' cog and slightly oversised lock ring. You now have a 13-36t cassette which gives you near enough the same ratio as the 11-34t on a 26er wheel. (O.K perhaps all unecessary if you went for a 10-speed 36t setup; but that wasn't in my pre-existing parts bin!).
Stoker leads by two teeth, pulling the captain through (a little). Avoid 90 degrees, I've used it on my kiddyback fine where there is a BIG difference in power), but off road, you will want to keep the pedals horizontal at times. Both sets of pedals 😉
Practice standing for the professional look, call bumps too.
Single-sided drive is a an obvious solution for a 2x10 mtb. Avoids the need for three left hand threaded cranks. In fact now we have such wide ranges at the back, it could become more common on the road too.
Some good tips - thanks.
Mad. As. A. Hatter. 
Bravo!
Now you've got me itching to build up an MTB tandem... enjoyed your pics... now any chance of some videos like this one? 😉
Good video. And for those wanting a shorter wheelbase tandem check this out (if I can work out how to post up a Video link).
No that didn't work - if anyone can tell me what I did wrong I would be interested to know meanwhile just paste this into a new browser and you will get there:- www.youtube.com/watch?v=5unMlXg6WL4
Heh, back-to-back tandems... wouldn't want to go off-road on one!
Video... needs the [i]http://[/i] bit?
Test:
O.K - that's the one! without posting it again just to do a test would that show in "Preview" prior to actually posting?
Fantastic!
Running timing chain on drive side is also "supposed" to make the rear bb last longer - tension from timing chain cancels out some of the tension from the rear drive chain. Must admit we used to regularly kill our Cannondale rear bb (regular lh timing chain setup). And can also second the comment that timing chain clearance can be an issue sometimes (we chainsawed a few wooden bridge drop-offs).
Tandem sold now - we both had different lead legs when descending (pedals level) so never really felt 100% comfortable - eventually held a truce where whoever was steering got to have their chosen lead leg 🙂
That is AWESOME! My lad can't ride a bike due to his cerebral palsy but we just about get by on a tandem. I need to learn to do man stuff like weldying....
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/2#post-4295863 ]nail[/url]]without posting it again just to do a test would that show in "Preview" prior to actually posting?
Nope, doesn't show in preview... the forum software here is a bit daft like that.
Actually, I do have a question about using a Fox 26er fork... any issues with the fork offset being, well... wrong!
jonstanley - Presumably your referring to 29er forks that are built with more offset compared to 26er forks? Well if it's about foot clearance issue then I have had no problems; if it's a handling issue .... well who knows!!?? I havn't had a lot of experience of other Tandems and well it's absolutely nothing like riding a solo bike ... even the Stoker on the rear trying to steer (by habit) can be detected on the front. I will, however be chucking some 26" wheels on and also giving it a go as a 26er. But I can say that on my 29er solo bike which is a '06 Marin Wolf Ridge with a minor conversion at the rear linkage in order to take a 29er rear wheel I have converted my Fox Talas 150 RLC's 26er's to 29er simply by sliding on a set of 32 niner fork legs (with bushings in the correct position). I normally ride a size large but I did this to a Medium which gives me the same standover height with 29er wheels ...... well the end result is that I have no problems with handling and it is usually the bike I grab more often especially in bad weather as it offers so much more grip with 29er wheels.
slowrider - Member
That is AWESOME! My lad can't ride a bike due to his cerebral palsy but we just about get by on a tandem.
That's how we first discovered the mountain tandem. We were at CYB on a NATS weekend trip back in about 1996, I was riding, Sandy wasn't a rider then and was passing the time in the cafe. I came back down the final descent into the car park and could hear my wife screaming with laughter from about half a mile away! As I came out into the car park she went flying past on the back of a red cannondale tandem with moto triple clamps on the front.
Turns out it was 2 brothers, one of whom had CP, and this was how he got his biking kicks, stoking for his brother. With Sandy's ME, turns out it was a perfect solution for us too.
I did think about your crank system but it wouldn't work with the chainsets I had as I guess you need them without a billet pipe axle i.e not with outer bb bearings as you need to attach a right hand chainset pedal to the left-hand rear
Yep, captains chainset is my old Raceface Evolve just fitted wrong way round. Strip the pedals, take the axles out, swap them round, rebuild.
Rear is on a square taper BB, though I guess ISIS or Octalink would work too, so you can fit 2 driveside cranks. I had a spare set of the same pedals, so could put a RH axle in the LH pedal. Threadlock everything and touch wood I've not had a problem with anything trying to undo itself.
Well I have been repairing several broken Ali Mtb frames for years and never actually had any problems and I'm still thrashing them some of them and based on prior experience I don't expect any problems.
In which case, I wish you many miles happy thrashing 🙂
Rob
- steady now lets keep this clean! 😆I wish you many miles happy thrashing
So then going back to this altering the timing between captain and stoker.
Do you not find that when you do this that neither of you can get the cranks flat while stood up and rolling?
That drives me nuts.
- Rob, sorry I'm missing that one? why don't the pedals just stay with their relative cranks with lots of thread lock?Strip the pedals, take the axles out, swap them round, rebuild.
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/2#post-4296458 ]nail[/url]]Presumably your referring to 29er forks that are built with more offset compared to 26er forks? Well if it's about foot clearance issue then I have had no problems; if it's a handling issue .... well who knows!!??
Yeah... fork offset. I do know that with Santana, their road tandems have more fork offset compared to "regular" road tandems... they do it this way as apparently more fork offset lessens stoker induced steering, in addition to making the steering less sluggish. Hmmm.
- hmmm interesting do you think it would also reduce the possibility of that dreaded tandem steering wobble at low speed?they do it this way as apparently more fork offset lessens stoker induced steering
I havn't tried altering the timing yet so I personally can't comment but my partner is used to riding a slower cadience than me and she is always suggesting I change gear. Perhaps it would be interesting to try different sized timing rings between the front & rear? Would you then be pedalling to different cadiences with a variable timing? That may need some thought, I'm not sure what the effect would be?So then going back to this altering the timing between captain and stoker.
Do you not find that when you do this that neither of you can get the cranks flat while stood up and rolling?
Perhaps it would be interesting to try different sized timing rings between the front & rear?
I think you'd just end up having really bad pedal strike problems and fighting each other with which way you wanted to lean the bike while pedaling.
Just for the hell of it here's us at Brechfa on our tandem.
What's a tandem like on tight trails?
FB jnr has cerebral palsy and currently rides a trike. The back 2 wheels can be detached from the front and attached to my bike with a tag along style adaptor. The width of the rear 2 wheels preclude any narrow trails such as at the SE mtb mecca that is Bedgebury.
He gets upset that we are restricted to the family trail and wants to do the singletrack when my mate & his son branch off and do some sections of that.
Having seen this thread, I wonder if a tandem might be an option but wonder about it's steering through narrow trails?
- Rob, sorry I'm missing that one? why don't the pedals just stay with their relative cranks with lots of thread lock?
Conventional tandem chainsets have THREE left-hand threaded cranks - only the stoker drive side is a normal crank. All the others are on the "wrong" side to prevent the [url= http://en.wikipedia.org/wiki/Precession_(mechanical) ]pedals loosening[/url] under normal use. Some tandems, such as yours, use a single drive side. This means you can use conventional cranks, but may run into problems with chain overlap. SJS have always gone with this solution and used an outer chainring timing chain. My Dawes tandems use alternate drive.
As for timing offset. There is a lot of debate - see [url= http://www.thetandemlink.com/hobbes.html ]tandem@hobbes[/url] for further (endless) details. But I found that with a weaker stoker, just a couple of teeth detent was helpful for us. With the kids on the back, 90 degrees was better - this isn't off road, mind. You could try 180 degrees out of phase, just for fun. The [url= http://www.davincitandems.com/dv2.html ]Da Vinci[/url] system allows the stoker to freewheel, essentially giving arbitraty phasing.
tandemspeedstu - That's brilliant, what tandem is it you ride?
Having seen this thread, I wonder if a tandem might be an option but wonder about it's steering through narrow trails?
We've taken ours to Brechfa, Afan and Nant y Arian. Just to give you an idea if you've ridden any of them.
[url= http://farm3.staticflickr.com/2547/3849013327_18b80671f4.jp g" target="_blank">
[url= http://www.flickr.com/photos/sheldona/3849013327/ ]Mincy[/url] by [url= http://www.flickr.com/people/sheldona/ ]sheldonattwood[/url], on Flickr
It's one of JD Cycles home brand frames with Lyric and Hope Moto's on.
[url= http://farm7.staticflickr.com/6208/6039241084_f4c14df794.jp g" target="_blank">
[url= http://www.flickr.com/photos/stu-b/6039241084/ ]110813_132922[/url] by [url= http://www.flickr.com/people/stu-b/ ]singlespeedstu[/url], on Flickr
FB-ATB - I have ridden Bedgebury three or four times on a nornal bike; from memory, apart perhaps from a couple of small sections I rekon we could do it on the tandem with relative ease; but that as I say is only from memory (but I wouldn't attempt the black section).
We've done some pretty tight trails near us, it takes some work but they're doable. No video footage sadly. For instance, we've ridden this hairpin - the zig zag bit in the middle, going from right to left downhill.
Going down that, the rear wheel stayed still while the front end wnt all the way round the outside.
If you're close to us (Marple) then you;d be welcome to give the tandem a go
I've ridden at Afan, but a while ago pre kids, so the memory is a bit hazy!
I'll have to pay more attention next time I'm at Bedgebury to possible sections we could divert from the family trail to.
Got a while to go yet as FB jr has only just had his 6th birthday and has to improve his balance before he can sit on a saddle without any side supports that his trike currently has!
Neil
why don't the pedals just stay with their relative cranks with lots of thread lock?
We run SPD's, so there's a 'front' and a 'back' on each pedal. If you take the LH pedal and put it on the RHS, the SPD mechanism is facing backwards, so won't engage with a cleat.
singlespeedstu - Member
So then going back to this altering the timing between captain and stoker.
Do you not find that when you do this that neither of you can get the cranks flat while stood up and rolling?
just 1 or 2 teeth we don't really notice when level pedals, but Sandy will often shout that she wants to change lead foot.
nbt
thanks for the offer, we're darn sarf and jnr needs a bit more growing to do before we can take you up on that! And possibly Mum will need some convincing as he tipped his trike over at buckmore park kart track under my supervision.
I had to learn to ride the opposite foot forward to accomadate the stoker. 😆
[quote=tandemwarriors ]
just 1 or 2 teeth we don't really notice when level pedals, but Sandy will often shout that she wants to change lead foot.
We have this issue as we have opposite lead feet: I'm driving, so my lead foot is forward, if I try to go the other way then we're more likely to crash. We also struggle a bit on corners as I quite often drop the outside pedal whereas Mrs NBT will just coast round pedals level most of the time. Had one incident last week where we got to the bottom and she said "I normally take a different line over to the right"
"I know," I said, "I could feel you leaning that way to get me over there!"
We also struggle a bit on corners as I quite often drop the outside pedal whereas Mrs NBT will just coast round pedals level most of the time
Yep, we had that one too! Anyone riding behind us will hear me shouting 'left down' or 'right down' or 'level' so we get the pedal position correct for each corner, because Sandy can't see over my head unless she's standing, so doesn't know what's coming next.
Had one incident last week where we got to the bottom and she said "I normally take a different line over to the right""I know," I said, "I could feel you leaning that way to get me over there!"
Yep, which answers that question that non-tandemers always ask - "but you can't steer at the back". Oh yes they bloody well can!!!!
FB-ATB - Member
What's a tandem like on tight trails?
Challenging, is the answer! We can do the whole red route at Glentress (except magic mushroom/mushroom pie which are tight on a solo). There's just 2 climbing hairpins we can't get round, on the singletrack climb from the picnic bench to the fireroad climb to spooky wood. Just imagine you're steering a bus rather than your car.
that question that non-tandemers always ask - "but you can't steer at the back". Oh yes they bloody well can!!!!
I was quite shocked by how much influence the stoker had on steering the first time we had a go on a test tandem.
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/2#post-4297038 ]nail[/url]]hmmm interesting do you think it would also reduce the possibility of that dreaded tandem steering wobble at low speed?
...
I havn't tried altering the timing yet so I personally can't comment but my partner is used to riding a slower cadience than me and she is always suggesting I change gear.
For regular road half-bik, err, solo bikes... fork offset is 40~45mm. Co-Motion has 50mm on their tandems and Santana are "the benchmark" at 55mm. Long version of handling differences over at Tandem Geek's blog: http://tandemgeek.wordpress.com/2011/05/15/2011-santana-beyond-review-beyond-sublime/
So anyway, back to MTB tandems. If memory serves, a 26er Fox 36 uses 39mm offset? With 29er wheels, that's a fair bit less trail. "Old skool" 29er forks have 44mm and current 29er forks have 51mm. The £££ Manitou Dorado is 50.something mm... and the new Cannondale Lefty "as strong as a DH double crown" Supermax is 53mm (saw it listed with 60mm offset as well?!). Not knowing if you're a bottomless pit of money, I guess it would be interesting to see how a Fox 34 29er fork with that extra 12mm offset makes much/any difference?
As for peddling cadence... might be worth a shot at trying out proportional crank lengths? Longer (175~180mm) cranks for the captain, so can't spin as fast... and shorter ones (<170mm) for the stoker, making it easier for them to spin?
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/3#post-4297432 ]tandemwarriors[/url]]Yep, which answers that question that non-tandemers always ask - "but you can't steer at the back". Oh yes they bloody well can!!!!
Indeed, even when the stoker at the back is just over 5ft and a lithe 105 lbs "ready to ride"! Am tempted one day to get them to captain instead, if it weren't for the bike-fit issues...
[shameless plug]
if anyones interested in doing the fox fork 26 to 29 bodge I'm selling some brand new Fox f29 lower legs that have new seals and bushings fitted..
[shameless plug ends]
top thread as well 😀
IIRC MSC have a freewheel fitted in the back crank to help with timming problems.
I've sorted the crankset issues on the last three tandems I've built (including the "Orange" 55) by using three relatively cheap cranksets, reaming/rethreading the pedal threads and using thread inserts to reverse threads/sides, fairly simple and effective so far. You just need a good grade of threadlock and cleanliness to get the sleeves well fixed. I couldn't be doing with the timing chain on the drive side as I wanted a full range of gears. Stuck with old style cranksets though, this won't work with integral axles.
I usually set the timing a tooth out either way depending on whether the stoker is stronger or weaker than the pilot.
[quote=identicalbutlighter ]
I usually set the timing a tooth out either way depending on whether the stoker is stronger or weaker than the pilot.
Which way do you set it for which scenario? I'm the captain and the stronger rider, should I set the stoker one tooth back?
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/3#post-4299401 ]identicalbutlighter[/url]]I've sorted the crankset issues on the last three tandems I've built (including the "Orange" 55) by using three relatively cheap cranksets, reaming/rethreading the pedal threads and using thread inserts to reverse threads/sides, fairly simple and effective so far. You just need a good grade of threadlock and cleanliness to get the sleeves well fixed. I couldn't be doing with the timing chain on the drive side as I wanted a full range of gears.
So was it your steel(?) "Orange" "Strange" (in orange, natch) tandem I saw a while ago back on here? There any more photos/videos of said beastie built up and being ridden?
On the subject of all right-side drive for an MTB tandem... I thought with some triple cranksets, it's possible to get a 4th ring (~36t) beyond the big ring?
I set the stronger rider just ahead of the weaker to pull them over TDC, seems to work, perhaps it's my imagination.
Yes that's the tandem, there were some photos lurking from the STW. My son has some GoPro footage but he's not got round to editing it, mostly it consists of me screaming with fear on the back.
Achtung!
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. Do you have any links to the threads?So was it your steel(?) "Orange" "Strange" (in orange, natch) tandem I saw a while ago back on here? There any more photos/videos of said beastie built up and being ridden?
therealhoops - That looks a very interesting beast - is it a home brew? any more pic's especially in close-up?
[quote=[url= http://singletrackworld.com/forum/topic/interested-to-see-26er-tandem-hadtail-conversion-to-mtb-29er-full-sus-tandem/page/3#post-4300559 ]identicalbutlighter[/url]]I set the stronger rider just ahead of the weaker to pull them over TDC, seems to work, perhaps it's my imagination.
Yes that's the tandem, there were some photos lurking from the STW. My son has some GoPro footage but he's not got round to editing it, mostly it consists of me screaming with fear on the back.
I generally spin fairly smoothly, though have had tandems set up with the stoker leading... so as to not whip the pedals from underneath the stoker.
Can you point us to the photos? I had a good rummage around STW and couldn't find them anymore. Videos would be even cooler... the Intertubes are much lacking in tandem MTB videos. 🙁
As for that beast of a tandem... looks like a no-longer-made Nicolai Nucleon FR Tandem?
Couple of videos here courtesy of TJ who is not allowed to post but is following this thread with interest