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Down South Yooper
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Discussion Starter · #1 ·
Ok folks, I've got a line on a GT Quatrefoil tandem, with the bastard sized 700d wheels that GT was pushing at the time. I am thinking, if I can get the thing cheap enough, that I'd like to convert it to 650b to open up the tire options.

Currently, it's rim brake only, but the 700d to 650b size change works fine (~3mm between the two sizes), but my question is, what rims are available that will hold up to tandem use, anything over 32 or 36 hole? Do I need more?

Use would be mostly road based, towing the kid's trailer, with some occasional trail use. I'd want something that I don't have to worry about..

What do you recommend? Walk away now?

Thanks.

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Harshing my mellow, man..
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Why not just use the same rims with 650b tires? Seems like the easiest way to go. The 650b will fit on the 700d wheels just fine, almost better than 650b specific rims.
Just a suggestion.
 

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Down South Yooper
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Discussion Starter · #3 ·
locobaylor said:
Why not just use the same rims with 650b tires? Seems like the easiest way to go. The 650b will fit on the 700d wheels just fine, almost better than 650b specific rims.
Just a suggestion.
That's definitely an option, and maybe a good way to start off. Overall, the tandem needs a little work and I like a project. Wheelbuilding is a great way for me to spend an evening also. Plus, the 700d wheels are ~18 years old, not sure how much use they'll be up for. The bike is from '91.

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Down South Yooper
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Discussion Starter · #5 ·
Alright, so I've committed to buying the Quatrefoil, I'll probably pick it up later tonight. I need to check it out for clearances, make sure it'll fit the tires on the market before I jump in with a conversion.

I'm thinking that I want to check the length of the stock fork (1 1/8" threaded) and see if it's close to a surly 1x1 fork. If they're close, I'll make that swap early. I'll look around to see if I can get a disc tab added to the rear, then my wheel issues are basically solved, I can run whatever I can fit then..

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You are now required to post pics of this thing once you get it home. Those are your marching orders!
 

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Down South Yooper
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Discussion Starter · #7 ·
MMcG said:
You are now required to post pics of this thing once you get it home. Those are your marching orders!
SIR YES SIR!

Hopefully picking it up tonight, have been on the lookout for a tandem for a little while, kinda excited to have one that might be readily convertible to something other than plain jane 26er..

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Harshing my mellow, man..
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isn't this basically the tandem of a GT Tachyon? if it is, i'm pretty sure there are pictures of one on the Tachyon thread, and it fits 650b tires fine.
 

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Down South Yooper
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Discussion Starter · #10 ·
locobaylor said:
isn't this basically the tandem of a GT Tachyon? if it is, i'm pretty sure there are pictures of one on the Tachyon thread, and it fits 650b tires fine.
Yes, from what i've read, the 650b tires should fit OK. Not sure it has exactly the same clearance as the single frames though. They offered a ~2.0 tire for this size at the time, not sure how it actually measured out against current tires.

Picking it up this evening, I'll post some pics when I get a chance..

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Down South Yooper
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Discussion Starter · #12 ·
Got it home, need to get it cleaned up for some pictures. Came with 700d x 1.4 tires, araya RM 700d rims, XT brakes (canti front, u-brake rear), XT triggers and levers, DX rear derailleur, deore front. Deore timing set and drivetrain cranks, exage hubs, 7 or 8 speed (I think the triggers are 8 speed on a 7 speed cassette).

A quick measurement on the fork is showing the A-C length to be ~395. I have no issue running a 413mm 1x1 fork so that I can run a disc on the front. I'm going to hit up some of the local builders to see about a rear disc mount to bring it up to speed on that department.

I'll get some pictures up in a bit, have some house guests now. Need to remove the supersized gel saddles and the vertical bar ends currently installed..

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Down South Yooper
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Discussion Starter · #13 ·
Alright, here's the good, bad and ugly. Mostly ugly. Got it stripped down, have all the parts set aside for cleaning, replacement, ebay, whatever.

Just eyeballing it, I'm not optimistic about fitting a 2.35" 650b tire in there, it just looks tight. In the photos, the tires are the original (18 year old) 700d x 1.4" GT tires at ~70 psi (rated for 90). The sidewalls are cracking, so they won't be ridden.

Sorry about the photo quality, a small, dimly lit garage makes for piss-poor photos.

Who wants to chime in on tire fit? I have a set of 26" wheels here I can use to check fit on smaller wheels, but if I can run 650's, I think i'd prefer that over 26ers, but I need to be able to run a full size tire. Please keep in mind that the fork is likely being replaced with a 1x1 fork that should remove any fit issues from the front, and that the back is being converted to a disc brake (from the current u-brake).

Thanks.

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Down South Yooper
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Discussion Starter · #15 ·
MMcG said:
What about something like a Fatty Rumpkin?
Yeah, I don't think the Fatty Rumpkin or the new KP Slick will be an issue, I think they're roughly the same size as the ~1.4 that's in there now.

I've looked through the Tachyon thread a bunch of times, it appears that the 650b 2.35 Neo-Motos will fit, even though there's not a picture of them in the tandem frame specifically, they're fitting within the u-brake, so with a little faith I'm assuming the 2.35's will fit.

I've got a local builder lined up to do the frame mods after the new year, I'm going to have a rear disc tab added and the u-brake posts taken off. I'm going to have the cable/housing guides added for housing/hose runs, and pick up a surly 1x1 disc fork for the front end.

Overall, i think it's going to be sweet as a 650b with fatty slicks or the 2.35's for dirt work. Now, I just need to find a buyer for the 700d wheels to get those out of the way...

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Down South Yooper
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Discussion Starter · #17 ·
MMcG said:
Quiring for the disc tabs?

This sounds like it is going to turn out really sweet.
No, more local to me:

http://ZRcycles.com/

He's up for the project but my holiday schedule doesn't allow me to catch up with him until after the 28th, likely after the 1st sometime.

In the meantime, I'm biding my time cleaning up parts. I'm not sure what makes people think that additional grease is the way to make things work better. I will say that I'm pleased with how well everything came apart, not one tough screw, siezed pedal or stuck seatpost. Just lots of white lithium grease on everything.

I have to admit though, I still have lingering concerns about rear end clearance with the larger 650b tires. I may just have to buck up and buy a set to see if they'll fit or not, unless I happen to run into someone local with a 650b wheel/tire to try out.

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Down South Yooper
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Discussion Starter · #18 ·
Quick update on this project:

The frame has been delivered to the frame builder for the disc tabs to be added, along with full housing cable runs for the rear disc and derailleur (having the saddle tabs added). I'm also having the extra cantilever/u-brake mounts taken off the frameset, just becuase it's already there. It hasn't been determined what we want to do for the front derailleur cable routing, leave it as-is or re-do it, but we're going to discuss that after the builder thinks on it for a while, suggestions are welcome. Currently, the derailleur routing is downtube to boom tube, under the bb's. The rear derailleur is going full housing, probably along the frame diagonal. Rear brake routing will be under the TT to the seatstay junction (just ahead of the ST on this frame) and then down the seatstay.

I've also got a DMR trailblade fork (QR) in the basement, so I'm set for discs front and rear. I've got a set of 2.35 Neos on the way as well.

All the tandem specific parts are cleaned up and ready to go back on, the big ticket items left to purchase are the wheels.

I'm pretty well settled on a WI M16 rear hub and a Hope Pro II front hub, both 36 hole, and the P35's in 36 hole. I'll get the front as a bolt on, but it's easily convertible if I go 20mm or QR in the future. Velocity has the 36 hole rims in white and silver currently (and I have the part #'s to order through your LBS if anybody is interested) and the black ones are expected around march. I'm going to wait for the black ones, unless I don't.

I'm expecting the frame to be another 2-3 weeks before it's ready for pickup, no hurry since I'm still accumulating parts. Also need to decide what to do about paint, but I'm thinking about just touching up the paint for now and riding the thing before committing to a full repaint.

I'll post up some pictures of the frame once I get it back..

Oh yeah, if you're curious, I have about ~$400 invested so far for everything. I expect the finished build to be in the $1000 range, with most of that being wheels (~$500). I got the complete tandem for $300 and parted out some of the orignal build.

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How do you plan on using the Tandem - as a true tandem off road mountain bike?

The P35s will be tough - but won't they make any tire a little bit "wider" than if you went with a different rim that isn't as wide? Do they make a Synergy in 36H?

When I had the Carver Ti Bumblebee on longterm test - that came with a Synergy rear rim laced to a Deore disc hub. The rim outlasted the hub. Never had a problem with the rim at all and I rode the bike hard per Davis' recommendations.
 

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Down South Yooper
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Discussion Starter · #20 ·
MMcG said:
How do you plan on using the Tandem - as a true tandem off road mountain bike?

The P35s will be tough - but won't they make any tire a little bit "wider" than if you went with a different rim that isn't as wide? Do they make a Synergy in 36H?

When I had the Carver Ti Bumblebee on longterm test - that came with a Synergy rear rim laced to a Deore disc hub. The rim outlasted the hub. Never had a problem with the rim at all and I rode the bike hard per Davis' recommendations.
I'd like for the tandem to have the ability to be used off road without concern, but in reality, it will likely see more around the town type of use at this point. I think I'm going to try a set of these:

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

to save the wear and tear on the Neos.

I do have a concern about the P35's and running a narrower tire, but a 45mm tire *should* be ok. I haven't looked at the synergy rims too much, I went straight to the 'latest and greatest' thinking that for a tandem, I needed all the beef and size I can get.

As far as I can find, I will be breaking new ground with 650b rims on a mtn tandem, so I'm definitely looking for any feedback on the topic that I can get, especially when it comes to rim durability..

edit - The synergy is available in 36 hole drilling, but clocks in at ~100g UNDER the weight of the P35. Going on listed weights alone, it would point to the P35 as 'king of the beef'.

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