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Tandem racing conversion

Old 06-03-24, 05:43 AM
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Tandem racing conversion

Hello,

My name is Daniel and I am from Germany. I am quite new to tandems. My girlfriend and I have a lot of fun riding tandems and so I bought one. As we would like to use it as a sports bike, I am currently planning to convert it to a “racing tandem”. I would like to share my thoughts and plans and hope to receive suggestions for improvement from you.
The basis should be the Shimano 105 groupset.

Gearing:
My plan is to install a 2x11-speed combination with a 50T and a 34T chainrings on the crank. For the drive to the pilot, the plan is to screw on a 3rd chainring with 34T. I don't yet know exactly what I need for this, whether I simply must use longer bolts or how exactly I should do this. If anyone is familiar with this, please let me know. At the front, the crank is only ridden with the small chainring.
The second idea is to connect a 3-speed crank with a 2-speed shifter.

Brakes:
I plan to install the Shimano 105 BR-R7170. I have already found the adapter from IS system to flat mount. The only question is whether the currently installed steel braided lines of my Magura Louise brakes will fit the Shimano ... or whether I must install new lines with olive and pin.

Tires:
Is it possible to run a 28mm wide tire for road use or is that unsuitable for the load?
What number of spokes would you choose and which hub is recommended?

Is there an option to get the Crane Creek Ergo stoker lever dummy or something similar for a drop handelbar?

I Would like to attache some pictures, but i think there is a restriction on my new account.

Cheers
Daniel
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Old 06-03-24, 07:26 AM
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Originally Posted by WaScHiaGGro
Hello,

My name is Daniel and I am from Germany. I am quite new to tandems. My girlfriend and I have a lot of fun riding tandems and so I bought one. As we would like to use it as a sports bike, I am currently planning to convert it to a “racing tandem”. I would like to share my thoughts and plans and hope to receive suggestions for improvement from you.
The basis should be the Shimano 105 groupset.

Gearing:
My plan is to install a 2x11-speed combination with a 50T and a 34T chainrings on the crank. For the drive to the pilot, the plan is to screw on a 3rd chainring with 34T. I don't yet know exactly what I need for this, whether I simply must use longer bolts or how exactly I should do this. If anyone is familiar with this, please let me know. At the front, the crank is only ridden with the small chainring.
The second idea is to connect a 3-speed crank with a 2-speed shifter.

Brakes:
I plan to install the Shimano 105 BR-R7170. I have already found the adapter from IS system to flat mount. The only question is whether the currently installed steel braided lines of my Magura Louise brakes will fit the Shimano ... or whether I must install new lines with olive and pin.

Tires:
Is it possible to run a 28mm wide tire for road use or is that unsuitable for the load?
What number of spokes would you choose and which hub is recommended?

Is there an option to get the Crane Creek Ergo stoker lever dummy or something similar for a drop handelbar?

I Would like to attache some pictures, but i think there is a restriction on my new account.

Cheers
Daniel
Gearing: it's probably easier to do with the older style 5 bolt crank set, ultimately it will depend on the clearance you have with the frame and the chain line.
Brakes: if you are converting from flat bars to drop you may need to change brake lines anyway. This might help. https://www.google.com/url?sa=t&sour...VITQUS-6YFnKdv
Tires: depends on your weight and what wheels you have, a stout 28mm tyre will be tougher than a fragile 32mm. Again with spokes we ran Rolf wheels with 20 spokes but have moved to 32 spokes in a conventional wheel.
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Old 06-11-24, 12:50 PM
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Originally Posted by WaScHiaGGro
Gearing:
My plan is to install a 2x11-speed combination with a 50T and a 34T chainrings on the crank. For the drive to the pilot, the plan is to screw on a 3rd chainring with 34T. I don't yet know exactly what I need for this, whether I simply must use longer bolts or how exactly I should do this. If anyone is familiar with this, please let me know. At the front, the crank is only ridden with the small chainring.
The second idea is to connect a 3-speed crank with a 2-speed shifter.
Might we ask what tandem you are planning to modify? If it came from the factory set to be one kind of bike, it just might not be worth the time and effort to try and make it into another kind of bike. For what you might spend trying to make your tandem into a sport tandem, you could find a nice 1990's Burley Samba or Cannondale Road Tandem ($500 USD to $700+ USD) or whatever German/European bikes fit into that price range. In our opinion, a tandem, no matter what it's purpose (except competition), should have the widest possible gear range you can afford. Our sport tandem has a 53/39/24 triple (105) and the rear end has 11-27 9sp. It's an old bike (2005) it's plenty sporty. The speed is in a low weight and a strong team. 28mm Schwalbe Marathon (not Marathon Plus). Keep the pressures high in the tires. Whatever the max limit on the side of the tire, keep it there.

A conventional setup with the drive to the Pilot (we call them Captains in the US) will be necessary because (IOO) you will be keeping the triple a triple. If your donor bike is not already a triple with left hand timing chain to the Pilot you will have a more difficult project. In 2005, 9sp brifters cost the Moon (11sp did not even exist) so I used Dura Ace downtube levers and Tektro brake levers. I don't know what options there are for hydraulic brifters in a 105 format. While hydros might be nice to have, they are not actually necessary. Mechanical discs (Tektro Spyre) with 205mm rotors f/r should be up to anything two normal human beings can throw at them.

Your Stoker (co-pilot?) doesn't actually need drop bars like you do. Bullhorn bars are a common bar for Stokers on sport oriented tandems. But, yes, dummy levers (some people just shorten the blades of standard levers and jam the mechanism) are common as well. The Cane Creek (Dia-compe makes some too) like you mentioned. Why not? If you want to post pictures (I'd love to see them) you can private message a link to where you have them hosted or just send them to me and I can upload them for you. Cheers.

Last edited by Leisesturm; 06-11-24 at 01:02 PM.
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Old 06-12-24, 10:14 AM
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Hi there,

thanks for your reply. There are many good points in your answer.
It is a Red Bull Twin power STB 2000. I will post an link to the pictures after this post.
Yes you are right that i could have bought a newer one like a Cannondale, Duratec, or what ever brand, but i like to work on bikes and to modify them. I just didn't do a tandem before.

Do you think i will get problems on hills with a 50T/34T front and an 11 or 12 speed 10-51sp.?
There are options to use a doublet in the front. Duratec sells them with the chains on one side. See the configurator here: (I am still not alowed to post links, I will send it to you privately and you can post it afterwards.
For brakes i did find adapter to mount the 105 brakes to my setup with 200mm hydraulic disc brakes.

That was the same idea that i had. I have to talk to my stoker for the handelbar setup.
Do you have the link to the Dia-compe ones?

Regards
Daniel
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Old 06-12-24, 12:35 PM
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Originally Posted by WaScHiaGGro
Do you think i will get problems on hills with a 50T/34T front and an 11 or 12 speed 10-51sp.?
What kind of hills are you talking? And do you mean a 10-50T cassette?

My stoker prefers drop bars with these stoker pegs
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Old 06-12-24, 03:39 PM
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Do you propose to have timing chain and drive chain on the same side? I am not sure what you mean by "to screw on a 3rd chainring"?
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Old 06-13-24, 12:23 PM
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Originally Posted by WaScHiaGGro
Hi there,

thanks for your reply. There are many good points in your answer.
It is a Red Bull Twin power STB 2000. I will post an link to the pictures after this post.
Yes you are right that i could have bought a newer one like a Cannondale, Duratec, or what ever brand, but i like to work on bikes and to modify them. I just didn't do a tandem before.

Do you think i will get problems on hills with a 50T/34T front and an 11 or 12 speed 10-51sp.?
There are options to use a doublet in the front. Duratec sells them with the chains on one side. See the configurator here: (I am still not alowed to post links, I will send it to you privately and you can post it afterwards.
For brakes i did find adapter to mount the 105 brakes to my setup with 200mm hydraulic disc brakes.

That was the same idea that i had. I have to talk to my stoker for the handelbar setup.
Do you have the link to the Dia-compe ones?

Regards
Daniel
I tried to find that Red Bull tandem but could not do so. I did find the Duratec site. Interesting. I do not think they are using a longer bottom bracket spindle to get clearance for the 3rd chainring (timing ring). Modern front derailleurs are very precise to purpose, and a 2x FD is simply not going to move far enough laterally (sideways), and a 3x FD will not have the right cage shape to shift a 50/34 compact crank properly. You could run the timing chain outside of the drive rings but you would have to use 50T timing rings! 10 - 51 gives you the same 18" low gear we have on our knock-around town everyday use tandem. Good for VERY steep hills with a load. For sport purposes you don't need to go that low. An 11 - 42 would be a lot lighter (lighter in $$$ as well) and easier to find. You won't use the 11T much if at all. 12T would be better but 11T top cogs are about all you are ever going to find. What rear derailleur are you going to use to shift an 11-42 12sp cassette? You'll need an MTB (mountain) type RD and they may not work with your shifters. The Dia-Compe dummy brake levers are not in active production. I found a set on Ebay. You can compare those with the Stoker Pegs linked by someone else.
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Old 06-14-24, 11:46 AM
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Hi,

Sorry for the late answer.

What kind of hills are you talking?
gradient of 6-8% on average for maybe 1-2km.

And do you mean a 10-50T cassette?
yes i mean the 10-50T cassette.

Do you propose to have timing chain and drive chain on the same side?
Yes i propose to have the timing and drive chain on the same side.

I am not sure what you mean by "to screw on a 3rd chainring"?
Do screw on a 2sp. cassette a 3rd chainring. Same size as the smaller one. Im aware that i have to manifacture propper bolts by myselfe. But that is not the problem I have a milling machine.

I tried to find that Red Bull tandem but could not do so.
I will post some Pictures in the end.

I do not think they are using a longer bottom bracket spindle to get clearance for the 3rd chainring (timing ring). Modern front derailleurs are very precise to purpose, and a 2x FD is simply not going to move far enough laterally (sideways), and a 3x FD will not have the right cage shape to shift a 50/34 compact crank properly. You could run the timing chain outside of the drive rings but you would have to use 50T timing rings!
First question, what is "FD"?
I also do not think that they using a larger bottom bracket spindle. The idea was to just place an chainring to the inside. But it turns out there is not enough space.
Just to clearify, i didn't wanted to do it with screws and washers ... that was only a test.






The Idea was to do it with a milled bolt.

So my next question is, what crankset with racing shifters can I use instead?





Regards
Daniel
​​​​​​​
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Old 06-14-24, 12:12 PM
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Or another idea:
Can I use Bracket spacer? Like that? Spacer

Cheers and a nice weekend
Daniel
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Old 06-15-24, 07:02 AM
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Rather than making your own, see if you can find a MountainTamer Triple, Mavic triple adapter (rare - I have one) or one of the other triple-izer adapters.

I ran a MountainTamer Quad on our tandem for years to get the really low gearing but the shifting up to the granny ring sucked badly.

https://mountaintamer.com/+
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Old 06-15-24, 07:43 AM
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Like i said in my first post, a four bolt crankset is going to be much more difficult. I have lengthened a crankset axle by 10mm by sleeving and welding two together. FD means front derailleur. our gearing is 33 46 front with a 11 36 rear using a grx rear derailleur which is good for 30mph.

TTing on the tandem.
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Old 06-15-24, 07:49 AM
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Originally Posted by scycheng
Rather than making your own, see if you can find a MountainTamer Triple, Mavic triple adapter (rare - I have one) or one of the other triple-izer adapters.

I ran a MountainTamer Quad on our tandem for years to get the really low gearing but the shifting up to the granny ring sucked badly.

https://mountaintamer.com/+
its a 4bolt chainset
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Old 06-15-24, 07:57 AM
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Originally Posted by WaScHiaGGro
Or another idea:
Can I use Bracket spacer? Like that? Spacer

Cheers and a nice weekend
Daniel
if you use a mountain bike bottom bracket they are slightly narrower that a road one which will allow you to use spacers.
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Old 06-15-24, 07:59 AM
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Originally Posted by mikemelbrooks
its a 4bolt chainset
Someone probably makes one by now. I use mostly 5 arm cranks on my tandem and single so I don't have that problem.

Seriously, most of these triplizers were built when square taper was king. Good luck. You can always machine your own if you have access to CNC milling machine.

https://www.redclovercomponents.com/...riplizers.html
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Old 06-15-24, 09:01 AM
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If you want to go fast, aero is the key. I added aero bars to both the captain's and stoker's position as shown below. I cut a piece of aluminum pipe to the just right length and attached aero bars for the stoker's position. Her hands are right beside my butt. Other than that, tandems are complicated. As mentioned above, you'd be way ahead buying a used modern tandem. Gearing will depend on how strong your team is. The only way to figure that out is to ride the bike in the steepest terrain you are likely to encounter. Thus you will be more likely to succeed if it's easy to get parts to modify the gearing as necessary, which means a relatively modern bike for which parts are easily available. Our bike is a 2003. Everything we need for it is still available. Older than about 2000, a wide variety of parts become harder to find. And of course, fit for both positions is very important. You'll want to be able to put on the correct crank lengths for both positions.

This is us going out for a winter group ride. We've hit 65 mph on descents. We used 28 mm tires for many years. Continental GP5000 tires are by far our favorite. We currently use 32mm. Our wheels are 36 spoke with Sapim CX-Ray spokes. The most important thing in a tandem wheel is that it be a deep rim, more important than the number of spokes. We could use fewer spokes, but the bike came with 36 hole hubs.
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Old 06-15-24, 10:11 AM
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Thank you all for your advices.
I will do some mesearments and will than decide what i want to do.
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Old 06-15-24, 02:15 PM
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Originally Posted by WaScHiaGGro
Same size as the smaller one. Im aware that i have to manifacture propper bolts by myselfe. But that is not the problem I have a milling machine.​​​​​​​
There are double length (10mm) crankbolts available.

Originally Posted by WaScHiaGGro
I also do not think that they using a larger bottom bracket spindle. The idea was to just place an chainring to the inside. But it turns out there is not enough space.
Just to clearify, i didn't wanted to do it with screws and washers ... that was only a test.The Idea was to do it with a milled bolt.​​​​​​​
A proper crankbolt countersinks the threads inside the chainring and the bolt itself, and its head sits nearly flush (flat) to the inside surface of the chainring. If you used bolts like that, I think you would find that you do not need a different crank.

Originally Posted by WaScHiaGGro
So my next question is, what crankset with racing shifters can I use instead?​​​​​​​
Answered above.
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Old 06-20-24, 07:21 AM
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Hi everyone,

My activities have become more concrete. I have carried out further measurements and am now on the way to getting the parts.

I have another question about the wheels. Which wheel hub is suitable for tandems? Do I need special hubs that are suitable for tandems or will high-quality normal hubs do?
I need a width of 135mm on the rear wheel.

Best regards
Daniel Schmidt
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Old 06-25-24, 04:45 AM
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Originally Posted by WaScHiaGGro
Hi everyone,

My activities have become more concrete. I have carried out further measurements and am now on the way to getting the parts.

I have another question about the wheels. Which wheel hub is suitable for tandems? Do I need special hubs that are suitable for tandems or will high-quality normal hubs do?
I need a width of 135mm on the rear wheel.

Best regards
Daniel Schmidt
As long as you are not especially heavy a good quality hub should be fine.
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Old 07-01-24, 03:16 PM
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All tandems that I know of have a non-standard rear hub spacing of 145mm. A very few department store grade tandems use 140mm but none that I know of use the 135mm common to most mountain bikes. I am really doubting the suitability of this tandem the o.p. is working with for 'racing' activities. It sounds very old and very non-standard. This will show itself when money starts to be spent because it will be very hard to find parts that will work.
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Old 07-01-24, 03:25 PM
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Originally Posted by Leisesturm
All tandems that I know of have a non-standard rear hub spacing of 145mm. A very few department store grade tandems use 140mm but none that I know of use the 135mm common to most mountain bikes. I am really doubting the suitability of this tandem the o.p. is working with for 'racing' activities. It sounds very old and very non-standard. This will show itself when money starts to be spent because it will be very hard to find parts that will work.
You're right, the 135mm spacing is not standard for tandems. I've figured that out in the meantime. The bike is from 2007, but I still managed to use almost entirely standard components. I only had to help myself with two small milled parts for the cassette and the crankset. So far everything has been tested, only smaller parts are missing and on the way. I hope there are no major problems with the final assembly.

I will report in detail when I have assembled everything. I think it should be ready in the next 2 weeks.
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Old 07-02-24, 03:05 PM
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Originally Posted by Leisesturm
All tandems that I know of have a non-standard rear hub spacing of 145mm. A very few department store grade tandems use 140mm but none that I know of use the 135mm common to most mountain bikes. I am really doubting the suitability of this tandem the o.p. is working with for 'racing' activities. It sounds very old and very non-standard. This will show itself when money starts to be spent because it will be very hard to find parts that will work.
Our Calfee Dragonfly is about as racy as it gets, and it’s built for 135mm spacing, which was pretty standard for Calfee before everything went to disc and thru axles.

We use DT Swiss 240 hubs with no issues. DT Swiss 350 would be a bit cheaper and more robust.

Any higher end MTB hub with 135 mm spacing will work.
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Old 07-04-24, 11:53 PM
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Originally Posted by merlinextraligh
Our Calfee Dragonfly is about as racy as it gets, and it’s built for 135mm spacing, which was pretty standard for Calfee before everything went to disc and thru axles.

We use DT Swiss 240 hubs with no issues. DT Swiss 350 would be a bit cheaper and more robust.

Any higher end MTB hub with 135 mm spacing will work.
To be fair though, I don't think o.p. is working with anything close to a Calfee.
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Old 07-06-24, 09:42 AM
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True, but it does show you can build a tandem with 135 spacing and hubs that are not tandem specific.
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