Author Topic: Tandem Fit  (Read 2349 times)

Chris S

Tandem Fit
« on: 09 May, 2013, 07:10:56 pm »
Spawned from here:

https://yacf.co.uk/forum/index.php?topic=67258.msg1479338#msg1479338

I'm intrigued by this. I think getting a tandem to fit well is actually quite hard. By "fit", I mean well enough for long distance, and that's a big ask, even on a bike that isn't a compromise between two people. I think it's particularly hard to do for long distance because you've got to get a setup that's sustainably comfortable for two people, on the same bike.

I'm no expert by any means, but given a fixed (within limits) wheelbase, there's finite room in the space between the two wheels to get both positions "right" for each other.

We were very fortunate with the Longstaff; it was basically "our size" from the outset - that is to say, we could get positions that broadly "worked" for each of us, from that frame. It's a much more aggressive position for me, over or even forward of the front BB, much more head down, and "racier". We both still have a few bugs that need ironing out, even after over 5,000km of riding (I get neck pain - from that racier position, and am developing new muscles in my legs, fboab gets numb hands) but we're pretty close. My setup was invented from scratch because the previous tandem (the Swallow) was too big for me at the front, whereas fboab's setup was just right, and Bev and Lance at Longstaff's spent a  whole afternoon translating her setup from the Swallow to the Longstaff.

Whilst I think it's possible to walk into a shop and buy an off-the-shelf solo bike and get a decent enough fit for long distance, I don't think that's anywhere near as likely for a tandem.

marcusjb

  • Full of bon courage.
Re: Tandem Fit
« Reply #1 on: 09 May, 2013, 07:27:30 pm »
Definitely agree it is harder.

Our tandem is a touch too large really - I am pretty comfy on it, but Cass can not get it right - we've arsed about with stems, bars, saddles, the lot really. 

We would like to trade it in sometime and get something more tailored to us - but that means walking into JD or Peter Bird or Longstaff and handing over a large chunk of cash that we don't have at the moment.  We'd like S&S couplings etc. as well - so we're into megabucks territory really.....

One day,

Right! What's next?

Ooooh. That sounds like a daft idea.  I am in!

Re: Tandem Fit
« Reply #2 on: 09 May, 2013, 08:30:55 pm »
Having just done a windy 600km ride on Dobbin (Thorn touring tandem), I'm looking forward to getting Katina (the Santana) back. While in terms of ride, the Thorn is extremely comfortable (I normally describe it as having your favorite armchair on a flying carpet), the stoker position is quite small. The issue comes with a headwind, as it just doesn't have enough length to comfortably hunker down for long periods. Katina has a noticeably longer wheelbase, and a much longer stoker compartment. This means that I can comfortably put my hands forward and get out of the wind without Joth's back/arse getting in the way.
I tend to get some hand issues on both bikes, although as stoker I can always take them off the bars and give them a rub/shake as required. Again, it's when it's windy and I'm in one position for a long time that I get most problems. As long as I remember to change hand position regularly, I'm generally fine.
The other factor with tandems is Q factor. The Q on tandems is generally fairly large due to have the drive chain and sync chains. Joth has had issues when swapping between the tandem and a solo. He found putting pedal extenders on the solo helped (to make the distance between the pedals closer to that on the tandems).
We're pretty lucky in that there is not much difference in size, so it's much easier to get tandems to fit. There just isn't the market to get tandems made in every combination of size, so it's always going to be difficult to get a perfect off the peg frame.
California Dreaming

Re: Tandem Fit
« Reply #3 on: 09 May, 2013, 09:08:30 pm »
I think getting it right for the stoker is harder than for the pilot. We don't have an infinite range of bar height, and we're more limited in relation to the cranks, even if the frame size is theoretically right.
I think generally I'm quite forgiving of bike position, I've ridden 200k+ on (counts) 3 different geared bikes, 3 different tandems and 2 different fixed bikes. None of my bikes have the same seat height or saddle/bars differential and I get away with it. I'd love to be able to claim this is because I have a strong core but I think I'm just lucky.
The Swallow was great for me, almost straight away, and the Longstaff matches that, except that I lose space between me & Chris. keeff & Sue's Thorn has lower bars (I don't really understand how, when surely Chris's saddle is the same height) but apart from the numb hands kicking in sooner, it was fine.
Feline- our tandem has a telescopic stem, have you tried one of those?
I have short legs and long arms so maybe I'm just a more tandem-standard shape? I thought from WSD sales pitches that this was unusual for ladies, maybe tandem frames are actually more like two mens frames than a male + female sizing.
I have a much more upright position on the tandem than my solos, and ride much more on the tops (I don't have any hoods) and don't try and match exactly my solo position. There's no need/benefit. I don't think it's possible, anyway, as we couldn't match the saddle/cranks angle/distance, I don't think.

jogler

  • mojo operandi
Re: Tandem Fit
« Reply #4 on: 09 May, 2013, 09:31:38 pm »
When we bought our tandem we compromised in that the frame was a better fit for the stoker than the pilot.I always felt just a little to streched whereas Marj was just right.

Re: Tandem Fit
« Reply #5 on: 09 May, 2013, 09:52:47 pm »
Quote
The other factor with tandems is Q factor. The Q on tandems is generally fairly large due to have the drive chain and sync chains. Joth has had issues when swapping between the tandem and a solo. He found putting pedal extenders on the solo helped (to make the distance between the pedals closer to that on the tandems).
Which is  a  god  reason to  not  buy  a  Santana with  an unnecessary  rear  oln of  160mm. which means  long BB axle and difficulty with  front mech adjustments

Re: Tandem Fit
« Reply #6 on: 09 May, 2013, 10:19:01 pm »
Quote
The other factor with tandems is Q factor. The Q on tandems is generally fairly large due to have the drive chain and sync chains. Joth has had issues when swapping between the tandem and a solo. He found putting pedal extenders on the solo helped (to make the distance between the pedals closer to that on the tandems).
Which is  a  god  reason to  not  buy  a  Santana with  an unnecessary  rear  oln of  160mm. which means  long BB axle and difficulty with  front mech adjustments
Yeah, but the Thorn with a straight through drive (and triple) is no better. You can't get the drive chain come off on the inside and end up under the sync chain on the Santana either....
I don't know what the Q is like on the Rohloff tandems, but having a single chainring has to help. It does mean that you are stuck with a 36 spoke wheel though, which is not what I'd want on a fully loaded tandem.
Ultimately, tandem design is all about compromise. A bit like riding them really  ;D
California Dreaming