# 650b Tandem - Vintage (ish)



## Plum (Sep 14, 2004)

Just finished this little project up today, there's been a (more or less) ongoing post over in the bastard wheel forum, but I figured the final pics could go up here as well:

Full specs listed over here for the curious:

http://forums.mtbr.com/showthread.php?t=578055

Should be out for the first ride this afternoon..

Plum


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## bme107 (Jul 23, 2008)

All white just looks so clean, while at the same time it seems to be missing something w/o the stripes. I like your updated cockpit and wish I could do similar for cheap.

I've got a few pics of my completed ride but they are not on line yet I'll post up a few pics and you can compare the fork rake etc. There is a lot of bend to the original and I don't think your finished product is that far off. 

I haven't ridden it in 2 weeks so I can't recall the on/off-center feel of the steering. I do remember that it takes quite a bit of effort to muscle the beast while pulling a 95lb trailer. Because of this I was hoping to find a better bar and captain position, but then again I come full circle to being stuck with this stem and a straight bar. I also remember that I was wishing for a whole hell of a lot more brakes at times.


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## Plum (Sep 14, 2004)

We rode it around town for a while on saturday afternoon, had a chance to try and get used to the steering and such, it's definitely manageable, although I agree, it feels like a lot of work just to keep the thing pointed down the road.

My stoker swears that she's staying centered, but it feels like she's dancing back there. We did have our double chariot hooked up, which made for a pretty long package, but the chariot doesn't really introduce odd handling issues (IMO), it just adds drag to the package.

The updated brakes are probably the biggest gain from this whole project, and the reality of having access to actual mountain bike tires. I have a set of the fatty HD schwalbe tires coming from Rivendell, just to save wear and tear on the motos. I should probably swap out the rear moto for a quasi too, the clearance is 'just' there for the moto, any wobbles and I'll be rubbing for sure.

Plum



bme107 said:


> All white just looks so clean, while at the same time it seems to be missing something w/o the stripes. I like your updated cockpit and wish I could do similar for cheap.
> 
> I've got a few pics of my completed ride but they are not on line yet I'll post up a few pics and you can compare the fork rake etc. There is a lot of bend to the original and I don't think your finished product is that far off.
> 
> I haven't ridden it in 2 weeks so I can't recall the on/off-center feel of the steering. I do remember that it takes quite a bit of effort to muscle the beast while pulling a 95lb trailer. Because of this I was hoping to find a better bar and captain position, but then again I come full circle to being stuck with this stem and a straight bar. I also remember that I was wishing for a whole hell of a lot more brakes at times.


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## DeeEight (Jan 13, 2004)

Assuming the fork you used isn't dramatically longer than the old fork (which would slacken the angles and make it steer more like a truck) or has more offset (which would reduce the trail and quicken the steering), then you might have to consider swapping to a stiffer front QR skewer (find an old shimano or campy from the 80s... the steel lever ones) or upspec the front hub to something with a 15 or 20mm axle.


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## bme107 (Jul 23, 2008)

Sorry, I did not have a direct side shot on file to compare the fork angles.
Before our maiden voyage:


















from this:









to this:








(had to deflate the tire to get it through the u-brake)


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## Plum (Sep 14, 2004)

bme107 said:


> Sorry, I did not have a direct side shot on file to compare the fork angles.
> Before our maiden voyage:


I do like the black splatter paint, I guess I could still do that. A set of 2.1's is probably in my near future, at least on the rear, the front is fine. I have a set of these:

https://www.rivbike.com/products/show/schwalbe-650b-fatty/10-095

coming friday for around town type duty, might as well save the high-dollar nice rubber for actual dirt.

My the DMR fork is around 2" longer than the stocker, IIRC. I think it's around 450 A-C, whereas the stocker is just under 400, so I'm definitely 'choppered' out a little, but now that we've ridden it a few times, it's pretty managable. Still a little floppy, but manageable.

Plum


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## bme107 (Jul 23, 2008)

I probably should have gotten something with a road friendly profile but I wanted a tire at least 2.0" to be able to run a lower pressure. It seems that you have to jump from 1.75" slick to 2.0 knobby, there is no middle ground at this time. As you can see the stoker seat rails are pretty much on the clamp and any bit of cushion is welcome.

Did you find a replacement stoker seat post? What/where? New standard size with shims or old dia. spec? Probably shaved over a pound off the bike weight.

Do you have a 20/18 or a 19/17 frame? Could you throw it on a scale?
As it stands in the pictures above we are 19/17 and 48.xx lbs for your reference.


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## Plum (Sep 14, 2004)

Stoker's post was replaced with a Sakae TCO off ebay, the post it came with was the wrong size, so I had to replace. Overall length of each cockpit is fine, standover leaves a little to be desired. I'd be interested to compare overall wheelbase to a modern tandem that doesn't have the stoker 1/2 way up the captain's @ss.

I think ours is a 19/17, haven't weighed it, but I'll see if I can throw it on the scale. Those tires from rivendell should be pretty close to a 2.0 at over 47mm in width, but those are the only 'larger' non-knobby I found. Again, ours will probably step down to a 2.1 in the rear to gain a little clearance clarence. Quality on the rivendell tire is yet to be seen also, but I expect it to be well below the level of the neo-moto. At $25/tire though, I can wear out a pair before buying 1 more neo, so no harm done IMO.

Plum



bme107 said:


> I probably should have gotten something with a road friendly profile but I wanted a tire at least 2.0" to be able to run a lower pressure. It seems that you have to jump from 1.75" slick to 2.0 knobby, there is no middle ground at this time. As you can see the stoker seat rails are pretty much on the clamp and any bit of cushion is welcome.
> 
> Did you find a replacement stoker seat post? What/where? New standard size with shims or old dia. spec? Probably shaved over a pound off the bike weight.
> 
> ...


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## Plum (Sep 14, 2004)

Also interesting is that you have integrated seat collars on your frame, whereas I have separate QR collars that fit over the ST(s). Seems a very odd/minor thing to change. Not sure how many years these were actaully manufactured or if there's a S/N indication of what model year the frames are..

Plum



bme107 said:


> I probably should have gotten something with a road friendly profile but I wanted a tire at least 2.0" to be able to run a lower pressure. It seems that you have to jump from 1.75" slick to 2.0 knobby, there is no middle ground at this time. As you can see the stoker seat rails are pretty much on the clamp and any bit of cushion is welcome.
> 
> Did you find a replacement stoker seat post? What/where? New standard size with shims or old dia. spec? Probably shaved over a pound off the bike weight.
> 
> ...


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## bme107 (Jul 23, 2008)

Plum said:


> I'd be interested to compare overall wheelbase to a modern tandem that doesn't have the stoker 1/2 way up the captain's @ss.
> 
> Plum


I've got the wheelbase marked as 69" in my notes.
Ventana shows their 19/16 frame as 72.4"
Ellsworth shows their M frame as 73.8"



Plum said:


> Also interesting is that you have integrated seat collars on your frame, whereas I have separate QR collars that fit over the ST(s). Seems a very odd/minor thing to change. Not sure how many years these were actaully manufactured or if there's a S/N indication of what model year the frames are..
> 
> Plum


Oh yeah the seat post collars, I think I asked you about that way back if yours where shaved by the guy that did the frame work. Mine are integrated and have a bit of a downward half-circle cut out on each side. (see stoker stem thread) Can't reason out if it's good/bad/indifferent. I do need to replace all the QR's since the rubber gaskets are dry rotted and cracked.

I would assume that mine is older by the slightest of margins.

As far as age I think I remember gm123456789 saying that the Quatrefoil was produced 1990-1991 as a 700D and then it went away for a year or two and came back in 1993 or 1994 as a 26er, before GT ended tandem production. Don't take the dates as gospel, but rather a couple years with one tire size, some time off and then another short stint with the other tires.

I can't seem to remember the thread where he was talking about it. There are just so many sub-forums where this bike can be discussed. (GT, tandem, vintage/classic, new wheel trends.) I have trouble pointing the search engine to the right one when I'm trying to find old bits of info that are escaping me.


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## bme107 (Jul 23, 2008)

Plum said:


> My the DMR fork is around 2" longer than the stocker, IIRC. I think it's around 450 A-C, whereas the stocker is just under 400, so I'm definitely 'choppered' out a little, but now that we've ridden it a few times, it's pretty managable. Still a little floppy, but manageable.
> 
> Plum


Confirmed. My records show 396mm A-C.
Also, iPhone level app indicates 62.7deg head tube angle.
EDIT: that angle is definitely wrong. Please ignore.


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## Plum (Sep 14, 2004)

bme107 said:


> Confirmed. My records show 396mm A-C.
> Also, iPhone level app indicates 62.7deg head tube angle.


I don't think it's that slack, stock is/was somewhere around 70 degrees..

Plum


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## bme107 (Jul 23, 2008)

Yeah, that's definitely wrong. Can't figure out where I pulled that # from when transposing my shop notes to excel file.

The 1991 catalog says 70 degrees.


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## Plum (Sep 14, 2004)

Weighs in at 49.6 lbs with the neo-motos and a surly nice rack mounted on the rear. No lightweight.

I did get the new street tires from rivendell mounted up, they'll work fine as long as I can keep them from pinching. Max recommended pressure is 45 psi, which is mighty comfy, but without being able to really unweight either end for curbs, edges, etc, we'll see how long they last..

Plum


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## bme107 (Jul 23, 2008)

49.6? Ha. I'm amused that we're about 15lbs heavier than the new bikes.

Hopefully 45psi in 1.75" is enough when you are fully loaded. The old 1.4s maxed out at 60psi and were insufficient when mine was loaded with 350lbs. Even with 310lbs I would not be comfortable traveling far from home without a couple extra tubes.


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## TandemNut (Mar 12, 2004)

bme107 said:


> 49.6? Ha. I'm amused that we're about 15lbs heavier than the new bikes.
> 
> Hopefully 45psi in 1.75" is enough when you are fully loaded. The old 1.4s maxed out at 60psi and were insufficient when mine was loaded with 350lbs. Even with 310lbs I would not be comfortable traveling far from home without a couple extra tubes.


Assuming you're refrring to an off-road tandem, I have to ask: What new bikes are weighing 35 lbs? Unless it's a single-speed fully rigid setup, I doubt most off-road tandems would be that light.
Realistic weight for a Fandango 29'er is around 41-45, depending on build and size. I know one team that has theirs down to 39, but that's a super-light build. The custom steel frames are likely to be very similar weight-wise.


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## bme107 (Jul 23, 2008)

I don't know about custom steel builds. I may not be remembering correctly but I thought my search for a tandem this past spring was revealing late '90's to early 00's rigid Cannondales L/S in the 35-36-37lb range. Though sold as an off-road tandem in that configuration nobody here rides them as such. (at least no active posting members) I also assumed that they held near this weight until the fat tires were dropped in 2008 (?) 2009 (?), but maybe those aren't even considered off-road anymore. 

I understand there are no good direct comparisons because of our odd wheel size. Maybe the sellers were blowing a whole lot of smoke as well.


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## Plum (Sep 14, 2004)

*If* (and that's a big if) the weights were realistic, there's probably more factors there too. Rim brakes, 26" wheels, lighter wheels (non-disc hubs) and such. Again, anything less than 40lbs stock seems like a reach for a mountain tandem.

If I were to remove the surly rack, I'd probably be down to around 48 lbs, and that's using early 90's forged cranks, XT hubs (boat anchors) and ball and cup BB's. A newer setup with external BB cups, some nicer hubs and such and I could see it dropping up to 5 lbs, but even then, the cost to drop that weight would probably be pretty high..

I'm sure the cannondale framesets are lighter than the GT's, but not by 5 lbs..

Plum



bme107 said:


> I don't know about custom steel builds. I may not be remembering correctly but I thought my search for a tandem this past spring was revealing late '90's to early 00's rigid Cannondales L/S in the 35-36-37lb range. Though sold as an off-road tandem in that configuration nobody here rides them as such. (at least no active posting members) I also assumed that they held near this weight until the fat tires were dropped in 2008 (?) 2009 (?), but maybe those aren't even considered off-road anymore.
> 
> I understand there are no good direct comparisons because of our odd wheel size. Maybe the sellers were blowing a whole lot of smoke as well.


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## bme107 (Jul 23, 2008)

My post was not meant as bragging this or that, parts spec, or weight weenie stuff. 

Intent was "look how far 'we' have come". Took about 20 years but in that time "we've" been able to cut the rolling weight by about 20% (50->40lbs). That seems significant to me.


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## Plum (Sep 14, 2004)

bme107 said:


> My post was not meant as bragging this or that, parts spec, or weight weenie stuff.
> 
> Intent was "look how far 'we' have come". Took about 20 years but in that time "we've" been able to cut the rolling weight by about 20% (50->40lbs). That seems significant to me.


Agreed, if we get excited about tandeming (my wife wants to do a race or two already) then I could see getting into some current technology here, lots of room for improvement IMO.

Plum


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