Building a Ti tandem
01-21-19, 03:20 PM
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Building a Ti tandem
Greetings all,
I'm contemplating a Seven tandem build. I wanted to put a rohloff/gates drivetrain on it but am hearing there are better systems out there. I'm just hearing about the etap system. Our team is 460# and we will doing some loaded touring along with credit card tours. I'm trying to get the most range as possible and wonder if a gates timing chain along with a Shimano/Sram drive system might give us more low end for the mountains.
thank you
anavycrna
I'm contemplating a Seven tandem build. I wanted to put a rohloff/gates drivetrain on it but am hearing there are better systems out there. I'm just hearing about the etap system. Our team is 460# and we will doing some loaded touring along with credit card tours. I'm trying to get the most range as possible and wonder if a gates timing chain along with a Shimano/Sram drive system might give us more low end for the mountains.
thank you
anavycrna
01-22-19, 02:00 PM
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Bikes: DaVinci Joint Venture Ti S&S, DaVinci Symbiosis 27.5", Trek Emonda SLR 7, Motobecane Century Ti ETap AXS, Motobecane Fantom Ti hardtail, Diamondback Haanjo Carbon, Motobecane Fantom 4x4 29'er, SE F@R fatbike
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At 460# and considering loaded touring you probably want a wide range of gears and a pretty low granny. As the happy owner of 4 DaVinci tandems (2 road, 2 MTB), with the latest being a Ti S&S road bike, I'd recommend you take a look at what they offer. We're about 100 lbs lighter than you and don't do any loaded touring but with our team power to weight ratio and the terrain we regularly ride we make full use of the DaVinci range.
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny. Our mechanical shifting bikes have a similar range but have a quad in front rather than a triple. I don't think E-Tap can come close to that range, and it certainly can't do it as a continuous range with reasonable shifts between cogs and rings. Other manufacturers with conventional drivetrains can easily get you one end of that or the other, but usually not both.
For those happily riding doubles (or even single speed) tandems I'm not discounting that those setups work for many teams, but I'll take lots of gears and lots of range!
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny. Our mechanical shifting bikes have a similar range but have a quad in front rather than a triple. I don't think E-Tap can come close to that range, and it certainly can't do it as a continuous range with reasonable shifts between cogs and rings. Other manufacturers with conventional drivetrains can easily get you one end of that or the other, but usually not both.
For those happily riding doubles (or even single speed) tandems I'm not discounting that those setups work for many teams, but I'll take lots of gears and lots of range!
01-22-19, 08:57 PM
#3
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For wide range gearing, I would not recommend Rohloff. The hub is limited to 526% total range. To be fair, that’s comparable to all the 1X mountain groups and a bit wider than standard road groups.
You can achieve over 600% gear range with a handful of 3X or wide range 2X drivetrains. Cycles Chinook and House of Tandems both offer extended derailleur cages for SRAM Red eTap to allow 11-42 (or possibly wider) cassettes to work well. I’ve seen the Chinook extended cage with 53/34 chainrings and 11-42 cassette with a taut chain and good shifting in all the gears.
Shimano DI2 MTB derailleurs allow an 11-40 cassette with triple or 11-42 cassette with a double.
Cable actuated derailleurs are a viable option, too. With SRAM bits, you can mix road shifters and some MTB derailleurs in 10- and 11-speed. With Shimano parts, 8-, 9, and 10-speed road and MTB groups can be mixed.
You can achieve over 600% gear range with a handful of 3X or wide range 2X drivetrains. Cycles Chinook and House of Tandems both offer extended derailleur cages for SRAM Red eTap to allow 11-42 (or possibly wider) cassettes to work well. I’ve seen the Chinook extended cage with 53/34 chainrings and 11-42 cassette with a taut chain and good shifting in all the gears.
Shimano DI2 MTB derailleurs allow an 11-40 cassette with triple or 11-42 cassette with a double.
Cable actuated derailleurs are a viable option, too. With SRAM bits, you can mix road shifters and some MTB derailleurs in 10- and 11-speed. With Shimano parts, 8-, 9, and 10-speed road and MTB groups can be mixed.
01-22-19, 11:01 PM
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01-22-19, 11:07 PM
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At 460# and considering loaded touring you probably want a wide range of gears and a pretty low granny. As the happy owner of 4 DaVinci tandems (2 road, 2 MTB), with the latest being a Ti S&S road bike, I'd recommend you take a look at what they offer. We're about 100 lbs lighter than you and don't do any loaded touring but with our team power to weight ratio and the terrain we regularly ride we make full use of the DaVinci range.
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny.
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny.
Rode a davinci and really liked the independent cycling and the huge gear range.
We upgraded our tandem to e-tap and I will say it's really nice but it's not perfect. The DaVinci range with di2 sounds perfect.
01-23-19, 03:58 PM
#6
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Seven make great bikes (we have 2) and you will be happy with the resultsRohloff is pretty good and the range is fine. I myself after having built up a few rohloff wheels don’t really like the weight. We are just about to head off on a 3 week tour with our tandem newly upgraded to eTap and it’s working brilliantly. We are using a 50-34 with an 11/42 cassette which gives us a 22” low gear. Not really worried about not having a high gear. If we’re going faster than 60km/hr we’ll just tuck in and coast. For our trip to the Italy and the Dolomites in May, I’ll swap the chainrings to 46-30. Our power to weight is average but we are 320# and we only cc tour with our panniers weighing about 30#. At 460# I’d be losing some weight before you spend the big dollars on a Seven. Your position will change as your weight drops. Spend some money on coaching to help you stay motivated and buy the Seven as your reward for when you hit your goal.
Last edited by geoffs; 01-23-19 at 04:14 PM.
01-28-19, 06:07 PM
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I dont believe OneIsAllYouNeed was complaining one bit he was stating all of the difference in gearing available in different packages. I believe OneIsAllYouNeed is a mechanical engineer, bike builder, and tandem enthusiast, and creator of Cycles Chinook. I've never have had the pleasure of meeting him, but I would say he is very measured not to reply to your idiotic statement.
01-29-19, 01:07 AM
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TKramer
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I dont believe OneIsAllYouNeed was complaining one bit he was stating all of the difference in gearing available in different packages. I believe OneIsAllYouNeed is a mechanical engineer, bike builder, and tandem enthusiast, and creator of Cycles Chinook. I've never have had the pleasure of meeting him, but I would say he is very measured not to reply to your idiotic statement.
To address the low end on the Rohloff you could go with a 50T drive ring and approach the triple with 17.4 at the bottom and a still have respectable 91.3 at the top. To get any lower you have to go with chain instead of belt to avoid overtorque limits on the hub. So that might be the deal breaker for someone with their heart set on belt drive.
Rohloffs are not for everyone or for every type of riding. Which is really the only reason to discourage it. If you want a single versatile bike that can do many things well - like tour on one weekend and keep up with a sporty club ride the next, do not get one. You will want another bike for the swift ride fix. Assuming OneIsAllYouNeed's handle reflects his philosophy on number of bikes to keep, it's the narrowness of the overall versatility and "performance envelope" not just the gearing range that potential buyer's need to seriously consider.
01-29-19, 06:45 AM
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There are also additional practical reasons for a Rohloff especially if you are considering to travel and transport the bike. Easier on maintenance, no need to remove or mess with a dérailleur (not a huge deal for some...I understand) , easier to lay the bike down on either side or not running into mini angst about bending the dérailleur, shifting several gears at standstill, adjustments after chain repair etc ... The marginal additional weight in the back could also be balanced well if the captain and stoker weight difference is substantial.*
01-29-19, 09:26 AM
#10
Senior Member
Here are a couple of resources that might aide this discussion.
Gear calculator... Currently setup with the lowest allowable Rohloff gear ratio and an example derailleur arrangement.
Bicycle Gear Calculator
The Rohloff manual. Key snippet is the lowest allowable belt gear ratios for tandems with 26" wheels: "46/19,50/20,55/22,60/24". With larger wheels, the gear ratios may be reduced proportionally.
https://www.rohloff.de/fileadmin/use...015_03_web.pdf
It's true that I like my bikes to be versatile. I like having high enough gears for group road rides and low enough gears to crawl up steep hills. I like having tires that are smooth on pavement and on gravel roads. As for the username, I used to ride a fixie all the time. It might not have been the best tool for the job, but it didn't stop me. I bought my first tandem a couple years after making this account. My current tandem lives up to the username though. It'll fit up to 63mm tires; gearing is 53/34 x 11-42; it packs into S&S suitcases; the stoker compartment has a telescoping seat tube.
Gear calculator... Currently setup with the lowest allowable Rohloff gear ratio and an example derailleur arrangement.
Bicycle Gear Calculator
The Rohloff manual. Key snippet is the lowest allowable belt gear ratios for tandems with 26" wheels: "46/19,50/20,55/22,60/24". With larger wheels, the gear ratios may be reduced proportionally.
https://www.rohloff.de/fileadmin/use...015_03_web.pdf
It's true that I like my bikes to be versatile. I like having high enough gears for group road rides and low enough gears to crawl up steep hills. I like having tires that are smooth on pavement and on gravel roads. As for the username, I used to ride a fixie all the time. It might not have been the best tool for the job, but it didn't stop me. I bought my first tandem a couple years after making this account. My current tandem lives up to the username though. It'll fit up to 63mm tires; gearing is 53/34 x 11-42; it packs into S&S suitcases; the stoker compartment has a telescoping seat tube.
01-29-19, 03:29 PM
#11
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At 460# and considering loaded touring you probably want a wide range of gears and a pretty low granny. As the happy owner of 4 DaVinci tandems (2 road, 2 MTB), with the latest being a Ti S&S road bike, I'd recommend you take a look at what they offer. We're about 100 lbs lighter than you and don't do any loaded touring but with our team power to weight ratio and the terrain we regularly ride we make full use of the DaVinci range.
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny. Our mechanical shifting bikes have a similar range but have a quad in front rather than a triple. I don't think E-Tap can come close to that range, and it certainly can't do it as a continuous range with reasonable shifts between cogs and rings. Other manufacturers with conventional drivetrains can easily get you one end of that or the other, but usually not both.
For those happily riding doubles (or even single speed) tandems I'm not discounting that those setups work for many teams, but I'll take lots of gears and lots of range!
With a Di2 triple we have a 58x11 big gear and a 26 x 40 granny. Our mechanical shifting bikes have a similar range but have a quad in front rather than a triple. I don't think E-Tap can come close to that range, and it certainly can't do it as a continuous range with reasonable shifts between cogs and rings. Other manufacturers with conventional drivetrains can easily get you one end of that or the other, but usually not both.
For those happily riding doubles (or even single speed) tandems I'm not discounting that those setups work for many teams, but I'll take lots of gears and lots of range!
01-29-19, 11:18 PM
#12
TKramer
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Alan's tandem is a DaVinci with independent coasting. His front derailleur shifts over a 13/22(?)/29 triple cluster which is then doubled by the crankset rings to freewheel bracket ratio change. See the explaination here https://www.davincitandems.com/drivetrain-info/.
01-30-19, 05:30 PM
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Alan's tandem is a DaVinci with independent coasting. His front derailleur shifts over a 13/22(?)/29 triple cluster which is then doubled by the crankset rings to freewheel bracket ratio change. See the explaination here Drivetrain Info - da Vinci Designs.
I'm running syncro mode and did an out of saddle shift from the big to middle ring the other day. I've been trying to avoid that based on experience with other drivetrains, but the bike handled it without any drama. If I hadn't pointed it out I don't think my stoker would have noticed it was multiple shifts.
02-03-19, 06:55 PM
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Yup - it is a 13/21/29 so equivalent to 26/42/58 with an 11 speed 11-40 in the back. One of the advantages of the DaVinci system is that it allows you to run an XTR triple within its designed chainring size limits and still have a tandem-capable gearing range.
I'm running syncro mode and did an out of saddle shift from the big to middle ring the other day. I've been trying to avoid that based on experience with other drivetrains, but the bike handled it without any drama. If I hadn't pointed it out I don't think my stoker would have noticed it was multiple shifts.
I'm running syncro mode and did an out of saddle shift from the big to middle ring the other day. I've been trying to avoid that based on experience with other drivetrains, but the bike handled it without any drama. If I hadn't pointed it out I don't think my stoker would have noticed it was multiple shifts.
