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Understanding sizes

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Understanding sizes

Old 07-21-20, 10:02 AM
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Stroudy 
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Understanding sizes

I'm trying to find a 2nd-hand tandem (upgrade) that will fit my wife and I

What are the measurements people ask for? I'm a bit confused with seatpost tube length. With the varying geometries out there I don't know what use that number is. I mean what point would it be on a Helios?

For my stoker, I've not seen anything the height can't be fixed without raising the seatpost, but reach is a problem as she can feel cramped on the few we've tried.

Would BB (bottom bracket) to BB be a good start? Anything else?

Thanks all
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Old 07-21-20, 11:15 AM
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joeruge
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cramped stoker

You don't tell is your stoker's height. The problem is that almost all tandems from major suppliers have the same rear top tube length across all their sizes. So generally it doesn't matter if you get a small frame, or an extra large, the rear top tube is going to be the same length - something in the neighborhood of 27.5".

Sloping toptubes make it a little hard to see. But you can also check the distance between bottom brackets. You'll notice that regardless of brand or size frame, that BB distance is pretty constant.

And it really doesn't help to have a longer stoker seat tube. The longer seat tube will help you get the seat further from the pedals, but it doesn't help much (maybe a tiny bit) to get the seat further from the handlebars.

The only exception I've found is for Cannondale in Jumbo, which adds about 3/4" to the BB distance.

Anything longer will likely require custom sizing and BIG bucks!
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Old 07-21-20, 11:27 AM
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Leisesturm
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This is our Trek T900 and I don't know her measurements because it really doesn't matter. Trek only made them in one size! As you can see the Stoker compartment can fit child right through adult as far as height is concerned. "Cramped" as in front to back should be a non-issue when you are sitting upright as you must be with the flat bars. My stem is not original and neither are my handlebars. I have a good deal of forward lean and I like it that way. Here is a shot of the business end of our Raleigh Coupe. I converted it to drop handlebars after a year of ownership. It is an XL/M combination and is technically too big for me but it was the last one ever made and it was going for a good price and so we bought it!

I don't know how you found the tandem you presently own but you must know that buying used tandems involves a lot of compromise. You don't really get to 'shop' the way you do when buying single bikes. You will make your lives a lot easier if you confine yourself to a particular make or model and time period and watch and wait for something matching that to come up. Then after you have the bike you can make it fit (within reason) by aftermarket stems/handlebars/seats and posts. A much shorter than stock stem and compact bend dropbars makes the 'too big' Raleigh Coupe very comfortable for me to Captain. Only those shopping for custom bikes get to specify details of Stoker compartment space etc. and I suspect you don't get as much say as one might think because if you line up a bunch of custom tandems at the start of a tandem club group ride (as we have) they are all much more alike than they are different. Here is a short list of tandems to consider*. There really isn't much else out there.
*you are in the UK so take this FWIW

Trek T900 (Should be top priority, discontinued after ~2015)
Burley Samba (Excellent bike but maybe hard to find outside of US)
Raleigh Coupe or Companion
Cannondale (Have not had one, very stiff, high performance)
Fuji
KHS
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Old 07-21-20, 03:44 PM
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morganmarie19
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Most tandems come in standard sizes (e.g., M/S, L/S, etc) and the brand will give approximate heights for the captain and stoker that would be appropriate for that size. If the tandem is older, you can still usually find size information from Bikepedia/Bicycle Blue Book or from vintage catalogs online. When I was looking to buy a used tandem, I found that receiving measurements from the seller (seat tube length, captains top tube length, etc) was helpful in confirming what size the tandem was according to the brand, so that I could then see if the tandem would roughly match our height requirements. If it matches on paper, then that would warrant an in-person look and test ride.

Tandems like the Circe Helios are meant to be flexible when it comes to rider height. They claim that the captain can be between 4'11" and 6'5" while the stoker can be up to 6'. Obviously if either of you are on the higher end of those numbers, then things will start to get cramped.

Best of luck!
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Old 07-22-20, 04:52 AM
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Stroudy 
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Thanks for your comment, people.

I'm 6ft (180cm) and my stoker is 5' 6 1/2" (169cm) FWIW

There are a couple of T900's available to me now actually. There's also a Cannondale 23" 21" frame - that seems large - is that a jumbo? There's a Cannondale los dos - waiting to see the size for that though. I assume that would be a suitable road tandem albeit with 26" wheels.

Here's the Los Dos - thoughts?



I wonder how universal this size/geometry charts is? I'm not sure what "H" means, but the Horizontal top tube length looks good in all frame sizes for us. 72.5-73.8cm (28 1/2" - 29") compared to our current 61cm (24")


Last edited by Stroudy; 07-22-20 at 07:35 AM. Reason: Adding pic
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Old 07-22-20, 09:18 AM
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Leisesturm
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Sizing Charts are very individual to the particular manufacturer! They can use any letter of the alphabet to refer to any dimension on their bikes. However, as you can see, the Los Dos only comes two ways. While nice to know what exactly you are looking at in that photo, were it me, I'd HOP on that, and get the tape measure out when it's safely in my garage. That is a long Captain's stem. 110mm at least. At 6' you can probably handle it. You probably have room under the hardpoints to fit 47mm to 50mm rubber AND some budget (Planet Bike, Bontrager, SKS) fenders. You'd have a conversation starter for sure.
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Old 07-22-20, 10:35 AM
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morganmarie19
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The Los Dos is Cannondale's mountain tandem from the early to mid 90s. Looks nice, I would imagine the size Large would fit you better than a Medium. One other thought- you mentioned for it to be suitable as a road tandem. If you really are more interested in a road tandem, you'll either need to deal with the compromise of flat bars on the Los Dos or be prepared to invest in drop handlebars, brifters, etc to change the current set up. Just something to think about.
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Old 07-22-20, 10:46 AM
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Stroudy 
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I meant to say (thought it was in the screen grab) that size chart is from Cannondale

I've bought the bike listed. On eBay for 585 which ain't bad - all recent Cannondale tandems have gone for more than that, so I'm quite pleased.
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Old 07-22-20, 11:01 AM
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morganmarie19
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Congrats!
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Old 07-22-20, 11:37 AM
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You won’t be disappointed. We rode a Los Dos 22/18” for several years before upgrading. The Los Dos frame is now hanging on our garage wall waiting for me to rebuild it. Probably not going to happen in my lifetime😊
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