Tandem Cycling - Sizing Question: Distance between verticals?
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11-14-07, 12:37 PM
I am looking at buying a tandem online, so I can't try it out. This would be my first Tandem, and it is clear to me how important fitting is.
It is listed with standover heights for the Captain and Stoker respectively: 33.5 in and 32 in.
Distance between the verticals for captain and stoker respectively: 21 in and 27 in.
So, my standover height is pretty much from my crotch straight to the ground when my feet are 6-8 inches apart?
(I got confused by some method describing holding a book between my legs and measuring from the spine to the ground; it sounds like the book was just to give me a point at crotch height)
I don't know what I should measure to judge the distance on the verticals. Is this listing confused? I haven't found other posts in this forum referring to the distance between verticals.
11-14-07, 01:08 PM
To get a comparison for the standover, and maybe you've already done this, measure the single bike(s) you're now riding, and check out how much clearance you've got. Spread your feet apart a bit if you like.
Compare that to the possible tandem's measurements. You want the tandem's number to be no bigger than, or ideally smaller, than the single bike. So if your single has 35" standover, measured, then you're a pretty long-legged person. If the single has a 33" standover and it's "close", this might not be the best tandem for you to captain, unless you only ride and never mount/dismount.
As some other recent threads have mentioned, standover clearance is good for both riders.
A bit more standover on a tandem can be a good thing. If your single bike's seatpost barely sticks out of the seattube, you'll need more on the tandem just to accommodate the stoker's stem mount, etc.
"Distance between verticals" is an unusual description for a tandem dimension. Given dimensions of 27" and 21" for the stoker and captain respectively, the likeliest meaning is the horizontal top tube length, for the stoker and the captain respectively. The stoker dimension is larger, because the stoker stem points back from the captain seat tube, and the captain stem points forward. 27" is about an inch shorter than the low end of the range for quality production tandems, and therefore would be best suited for a first tandem for a petite stoker, with more length being something you might consider getting on a second tandem in the future.
11-14-07, 05:37 PM
So, the description says this is a "Larger sized frame that will fit medium to taller riders." my impression is that the the stand over heights of 33.5 and 32 are fairly tall. If the length of the horizantal top tubes (distance between verticals) is short at 21 and 27, would this bike be comfortable for anyone? Short people with long legs? This would be my first tandem, and probably fairly cheap, so I don't mind if it doesn't fit prefectly, but I'd like it to be close enough to get a sense of how it should feel.
I am 5' 11" and the stoker is 5' 7." I haven't yet tried to measure our standovers.
11-14-07, 06:52 PM
I think SDS is correct in the interpretation of "distance between verticals" -- it does sound like a (garbled) description of the distance between the head tube and the captain's seat tube, and the captain to stoker seat tube. There might -- might only -- be another inch or so there if they are measuring from face of tube to face of tube, since the normal bike geometry measurement is from center of tube to center of tube.
For the captain, again you can measure the top tube of your current bike. There is some flexibility to be gained by installing a longer or shorter stem to move the handle bars toward, or away from, the seat. For the stoker, there's not a whole lot of room to adjust IF the space is tight. SDS is right, "new" tandems are longer in this dimension than older ones were. If your 5'-7" stoker is long of torso, or long-armed, the tighter space may result in them being squished onto the captain.
11-15-07, 07:33 AM
I am prety sure these measurements correspond to our Large Trek T100, I'll measure it tonight and see if it matches. I am 6' wife 5 2" and fits fine, I have left over standover height, wife barely, but she stays clipped.
I think you will be fine with a 5' 7" stoker, I have stoked our bike once, and it was not too bad, small for me but I could ride it fine and I am 5" taller than your stoker. If you replace the flat bar for bull horns for the stoker she will be able to streach her arms more. Then move your seat a little forward, the stoker's move it back and you get another inch or two.
Our new Co-Mo has more stoker space. But as per my earlier post, if your budget is under $ 1000 you will need some compromises, the T100 is a good option, and Large is the size for your team, I suspect they did not make it any larger. But you might consider raising your budget for more options, and look for a more current bike, which might have more stoker room. Everyone here will tell you to get the best bike you can afford.
My T100 has the following measurements. Top & seat are center-to-center:
top tube, capt: 22"
top tube, stok: 28"
seat tube, capt: 22"
seat tube, stok: 20"
standover, capt: about 32" (tires are 700x28)
standover, stok: about 31" (tires are 700x28)
I'm around 5'10", and I usually ride about a 58 or 59cm road bike.
The T50/T100/T200 all appeared to share the same frame, as far as I can tell. Below is an older picture of my bike. I have seen pictures of this series with a larger frame -- most notably, the head tube looks to be at least an inch longer than mine. So, either mine is a medium, or they made an extra-large!
11-15-07, 10:18 AM
Gregm, I see that yours is a Double Cross at some point the name changed int the T100 from Double Cross to Double Track which is my model. I see also that you upgraded to indexed shifting and drop bars, but you kept the original brakes which I felt compeled to change. Did you spread the rear triangle as well?
11-15-07, 10:26 AM
The last page of this link
lists the components and shows the geometry of the Trek tandems from the 90's. Frames were all the same; for some models, sizes are stated in inches, for others, in centimeters, but that just depends on which tape measure they used.
Biggest frame was a 62/56 with 34.1/32.5 standovers (maybe just the thing for those 6'-1" Swedes!).
Notice that the Trek measurements are from center of bottom bracket to top of the seat tube extension above the top tube; not the same reference points as commonly used for single bikes, c-t-c bb to center of top tube, or c-t-t, bb to top of top tube.
11-15-07, 10:31 AM
from the Vintage Trek model/year/color matchup,
http://www.vintage-trek.com/model_numbers1.htm, it looks like Greg's bike is nominally a '92 or '93.
And it looks like he changed the bars from straight to drops.
Greg, do you recall your source for the brake cable hangers, front and rear?
you kept the original brakes which I felt compeled to change.
They have performed fine for me, so I haven't changed them. I've changed cranks/wheels/seats/BBs/bars/etc/etc, but not the brakes!
Did you spread the rear triangle as well?
No. The bike is 140mm. My current rear wheel is built around a hub I bought about a year ago, a Phil Wood 140mm 48spoke 9speed tandem hub with drum threads. Phil makes about any combination you need.
Greg, do you recall your source for the brake cable hangers, front and rear
Sure! They came with the bike. ;)
Ok, so that's not too helpful. I do consider this sort of a weak point -- what do you do if they become broken or damaged?
The front hanger is a little cramped under my low stem. With the giant steerer, it's probably a little tougher to find replacement front hangers that will fit.
I recently ordered a generic rear brake hanger as a potential spare for the current doo-dad that hangs off of the rear seat post clamp, but I haven't checked yet to see if it will actually fit!
Also, the rear hanger that came with my bike -- presumably stock -- does not have an adjuster. Kind of a drag. I keep meaning to install an in-line cable adjuster.
11-15-07, 03:46 PM
I have a bike built from the same geometry which came to me with V-brakes. I changed to new cantilevers and had to deal with the cable hangers. What I've got now on the front is a unit that goes up from the fork crown drilled hole, and a short-range cable adjuster, and on the rear, a doo-dad mounted on the rear seat post clamp, must be like yours there.
Sources included Nashbar, Loose Screws and some of the other on-line stores, and LBS's. I'm still thinking there must be some nicer quality units out there. I think I bought one of each steerer tube size before I finally got one that fit.
There are some simple in-line adjusters which you can put in the system where the rear cable/housing first contacts the frame, just behind the head tube. You can get enough adjustment/slack by loosening one there, to get the straddle wire off to release the rear brakes to get the rear wheel out.
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