Bikepacking Gravel Tandem Project
#1
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Bikepacking Gravel Tandem Project
Fresh off an inaugural two week back country ride across gravel and forest service roads thru Colorado on our new tandem, I wanted to share our latest tandem build in case the details help others with similar goals/build in mind. Our racing gravel tandem is "Coyote" So we dubbed the packing bike "El Burro" and went with a Mexican falsa blanket color scheme.
Our criteria were:
Our criteria were:
- 35 pounds,
- approx $10,000 budget
- Increased tire width from our current gravel racing from for packing tandem for 29x2.3 and for sand/rocky riding we do in AZ also fit 27.5x3.0
- Reconfigure how frame bags and bottles fit
- Non-suspension, non mountain bike geometry. IE: 50mm Bottom Bracket drop, straight not bent top tube, 427AC non suspension fork.
- Something bomb proof and drive train that works for long stretches in the back country..
Here’s the link to the build spec: https://docs.google.com/spreadsheets...iOF-KBFQjHgPP0
The highlights in my mind, or special custom applications are:
- Tight Q-factor road cranks. 156mm Q-Factor while still clearing large tires. Worked wonders on knee comfort
- Eagle 12 with right side timing chain, tight timing chain line: Increase reliability, no need to recharge electric shifting for long stretches in back country, right side drive has better efficiency tranfering captains power than left side timing
- BB 386 EVO 86.5mm bottom bracket shell gives good base for chain stays.
- Granite tandem custom proprietary eccentric
- 65mm offset ti fork from Blacksheep works well on washboard
- custom Dean Bikes 240mm stoker stem
- JPak custom bolt on bags
- I’ll refine the numbers, but in round figures 35# ready to ride bare bike, 45# with all the empty bags, bottles, and electronic navigation and lighting, 55# loaded with gear, rain gear, safety shelter, tools, first aid, etc. add 10 pounds for food and a big water day (we usually harvest water along the way and try not to over carry) comes to 65# fully laden.
with aspen trees how we ride back country in Colorado with 29x2.3 tires
- Inspiration image for the bag design:
Last edited by Turbotandem; 08-28-19 at 12:23 PM. Reason: added more photos
#2
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Such a well thought out build! You guys have outdone yourself Andy!
I just realized that you had to use a Eagle shifter on the top of your handlebars. Did you encounter many times when you were in the drops or on the hoods (braking) when you needed to shift? Hopefully not many.
It certainly gives me some ideas for future builds. But I am not sure that we would use a bike like this the way that you two do!!
Either way - you and Kami are inspiring! You need to share with the group your route, miles & vertical that you recently rode to break in El Burro.
I just realized that you had to use a Eagle shifter on the top of your handlebars. Did you encounter many times when you were in the drops or on the hoods (braking) when you needed to shift? Hopefully not many.
It certainly gives me some ideas for future builds. But I am not sure that we would use a bike like this the way that you two do!!
Either way - you and Kami are inspiring! You need to share with the group your route, miles & vertical that you recently rode to break in El Burro.
#3
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Bikes: Paketa V2r di2, C-Dale MT 3000, Teesdale, 1963 Huffy Daisey
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Such a well thought out build! You guys have outdone yourself Andy!
I just realized that you had to use a Eagle shifter on the top of your handlebars. Did you encounter many times when you were in the drops or on the hoods (braking) when you needed to shift? Hopefully not many.
It certainly gives me some ideas for future builds. But I am not sure that we would use a bike like this the way that you two do!!
Either way - you and Kami are inspiring! You need to share with the group your route, miles & vertical that you recently rode to break in El Burro.
I just realized that you had to use a Eagle shifter on the top of your handlebars. Did you encounter many times when you were in the drops or on the hoods (braking) when you needed to shift? Hopefully not many.
It certainly gives me some ideas for future builds. But I am not sure that we would use a bike like this the way that you two do!!
Either way - you and Kami are inspiring! You need to share with the group your route, miles & vertical that you recently rode to break in El Burro.
A short summary of El Burro's first big trip, which was a good proof of concept. We'd ridden her for a month before the trip including some really rough stuff in sante fe area. The main trip we just finished was 13 days of riding from Moab to Boulder 85% off-pavement, 715 miles, 54,100 feet of climbing, 80 hours in motion and some 96.5 hours on the road including lunch breaks. Two broken spokes, both in the front, both right at the end spoke end of the nipple: I think the spokes weren't threaded/cut well. One de-laminated tire. One crash on a back-country plank bridge with the planks running parallel to the direction of travel with gaps and uneven placement between them. Below is a map of the ride and profile and one picture. I don't know how long our spotwalla track will persist, but this link is shows our route and re-route to Boulder and you can zoom it to see more detail (this one does not show our track just the route): https://spotwalla.com/tripViewer.php...85b10bc7f61362
our route this year in pink
#4
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I added frame development pictures to first post, and here are some detail shots:
bags over chain, tool bottles in chain line
65mm offset fork by Blacksheep
ergon post stack height (the little blue collar is rubber decoration)
alternate narrower spider with 26t chainring clearance at 3.0x27.5 tire 2.5mm
alternate narrower spider with 26t chainring clearance at 2.3x29 tire
bar set up
shifter set up
side but side stoker bottles
Custom art for sewn patch, HA!
bags over chain, tool bottles in chain line
65mm offset fork by Blacksheep
ergon post stack height (the little blue collar is rubber decoration)
alternate narrower spider with 26t chainring clearance at 3.0x27.5 tire 2.5mm
alternate narrower spider with 26t chainring clearance at 2.3x29 tire
bar set up
shifter set up
side but side stoker bottles
Custom art for sewn patch, HA!
Last edited by Turbotandem; 07-16-18 at 12:58 PM.
#6
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Location: Florida
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Bikes: Paketa V2R tandem, Granite Tandem Design TI travel tandem, Lynskey R265, Specialized Diverge, and of course a unicycle
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Fabulous build and great adventures! We have a more road and travel oriented Granite Tandem, and love it. David is a pleasure to work with, and we are extremely happy with our bike. It's funny Andy, our other bike is a Paketa V2R, which is a special bike too!
Ethan
Ethan
#7
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was there any magic needed to make the road cranks play nice with the plus wheel and tire? boost cranks are the main reason i am reluctant to ride anything with plus tires.
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The SRAM Force BB30 cranks had their spindle replaced with one about 10mm longer. This widens the Q-factor, but also sets them up for having a proper chainline with Boost hubs.
The maximum theoretical tire size for a 1X drivetrain, Boost (148mm thru axle) rear spacing, and adequate tire clearance is 3.0”. Any wider and there’s risk of the chain contacting the tire in the lowest gear.
To use road crankarms with this maximum tire size, the chainstays were heavily manipulated. For this bike, @Turbotandem knew exactly what chainring size they would use, so the chainstay length was set to clear those chainrings. For larger chainrings with 3.0” tires, we would need to lengthen the chainstays.
Finally, the Force crankarms are compatible with aftermarket spiders. We tested a Wolftooth Camo arrangement, but that came with a limited range of chainrings choices. For this tour, they used an NSB 104/64 spider with some minor tweaks.
#9
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David provided the best outline; we leaned on him to hit the criteria we set. As you say, boost cranks are a hurdle we did not want to accept. In fact, we wanted a narrower Q-factor than we have on our other "normal" gravel tandem. David at Granite was able to configure the bike at 156mm stoker Q-factor in back, and a little less for the captain. I think we have about the tightest clearances from cranks to stays, chain to tire tread, and mud clearance for both the 29x2.3 and 27.5x3.0 as is reasonable and reliable.
Last edited by Turbotandem; 08-28-19 at 12:23 PM.