We’ve finally decided to buy a tandem after hiring one several times and loving it. The only problem is I’m finding the sizing tricky and we have no dealers nearby we can go to, to try them out. We’re looking at a Dawes Discovery Twin which comes in either 21/17 or 19/15. I’m going to be the stoker at 5′ 10″, inside leg 32″ and my wife is 5′ 6″. Having looked at the geometry chart (linked below) the reach on both sizes is the same, it’s just the seat tube that changes. Unfortunately the Dawes sizing chart (second link) isn’t entirely clear (to me anyway) as the stoker height is quoted as the same for both frame sizes.
I’ve done some comparison with the geometry chart and our existing bikes and I think we could actually fit either size but was wondering if anyone has any real world experience.

https://dawescycles.com/wp-content/uploads/2018/02/DISCOVERY-TWIN.pdf

https://static.evanscycles.com/production/pdf-media/sizing-table/dawes-duet-twin-tandem-sizing-chart.pdf

Many thanks.

No experience of Dawes tandems but…

We have a childback Thorn as my wife is similar height to yours it’s just on the limit for the USE sus post at min insertion.

You need to make sure the frame will be small enough for stoker to accommodate a suspension seatpost otherwise you can get comedy stoker ejection (your wife won’t find it funny)

Good luck

Thanks Swirly, funnily enough I was going to use this as an excuse to drag my old USE sus’ post out of the workshop. Just to confirm, are you saying that your child back tandem requires the seat post to be almost fully exposed to get the right ride height?

Yes childback has seatpost fully exposed. It’s a Sumo and extra long 400mm IIRC. Top tube could do with being slightly longer on rear but is manageable.

I’m 5’9″ and fits me well.

Remembered it’s a Thorn Voyager frame 26in wheel (I built it up from a Phillips doner bike)

If you think both are similar geometry wise I’d go smaller to make sure USE post will fit. A sprung saddle is another option of course.

Can you get 2 sets of bottles for each rider on both frame sizes? I added a stoker stem mounted water bottle which my wife prefers to use.

If you are interested, I’ve got a Dawes Double Edge that has been gathering dust for a few years. Would let it go cheap.

RichT, very interested, whereabouts are you?

The Double Edge is a great tandem, it’s the same frame as the Discovery. We used our Dawes (badged Dsicovery) for years and only sold it recently having upgraded. I’m 5’9″ and mrs NBT is 5’4″ – fairly sure we had the 19/15 frame and that’s what I’d recommend for you as the very first upgrade I’d suggest would be a Thudbuster seatpost. Friends had the smaller still frame size and they coped just fine at around the same heights as us. There was plenty of room for seatpost adjustment at th back, could have gone adjusted for a taller captain but wouldn;t have been able to fit anyone much smaller than me.

Nbt, that’s really helpful and I’ll take your advice. I’m no stranger to most areas of bike buying but tandems are a whole new avenue and I appreciate you taking the time to get in touch.

+1 for a thudbuster, I’d go for the smaller of the two frames if I were you if the reach is the same, tandems seem to be pretty versatile when it comes to sizing, we’ve used our 20/16 dawes discovery for touring and offroad with no problems but we are both a couple of inches taller than you two. If you get it right it can be addictive though 👍

AIUI, reach for the stoker isn’t an issue, it’s solved with (often very long) stems.

AIUI, reach for the stoker isn’t an issue, it’s solved with (often very long) stems.

Unless the reach is way too short – bought a beautiful old Mercian and found out the hard way, the reach was 4″ shorter than our Dawes 😕