In this megapost, we will attempt to answer any technical questions you may have about tandem bicycles and components, with a specific focus on bicycle touring.
We also have another article which runs alongside this:
- Tandem Wheels
Just like any bike wheel, the person who builds it is just as important as the materials you use. Find the best builder you can, we guarantee it will last longer.
Spokes: Tandem bike wheels typically have more spokes than standard bike wheels as this allows for a reduced load on each spoke, nipple, rim hole and across the hub flange. Tandem wheels can be found to have 36, 40 or 48 spokes. If your wheels are on the cheaper side, make sure you have 48 spokes, but if you run better quality gear, you will be able to get away with less.
26″ vs 700c: We chose to run 26″ wheels on our tandem so that we could maximise the strength of our existing 32 spoke wheels and run 2.00″+ tyres with mudguards. If we were doing it all again from scratch, my preference would be for a 29er disc specific wheelset with a few more spokes up front. You can read my comparison between 26″ and 700c wheels HERE.
Hub Width: There are a few hub sizes for tandems. 135mm rear spacing is standard for most bicycles, but tandem wheels can be found in 145mm and 160mm. At 160mm wide, rear wheels can be 'dishless' – building a stronger wheel because spoke tension is the same on every spoke.
For front riders on a tandem, handling is much more demanding on the upper body than on a standard bike. This is because the front rider needs to balance out shifts in weight made by the rear rider, in addition to managing the front bags (on a touring tandem) which slow the steering speed. My body took about a month of touring to build up the core strength required to manage our bike properly.
The best way to make handling a tandem easier for the front rider (especially for beginners) is by using a wide, flat handlebar. Wider bars increase the steering leverage and make managing loads much easier, as a lighter force is required to change the handlebar direction.
I run a drop handlebar because I like the positions it offers while touring, but would generally recommend a flat handlebar for most other tandem tourers out there. For my article 'All about bike touring handlebars' click HERE.
For rear tandemists, a flat or bullhorn handlebar is the most popular. These bars need to be relatively wide to make sure they clear the front rider's hips. Drop handlebars are not necessary because rear tandemists are shielded from the wind by the front rider.
The same as on any bike, tyre choice is important on tandems.
The wider the tyre, the more the tyre can absorb shock and depressions in the road. Wider tyres at lower pressures offer more stability for tandem bikes on rougher terrain as well as additional comfort to the rear rider – important because rear cyclists cannot prepare for bumps as well as those up front.
You will also find that wider tyres also reduce any tyre, rims or spoke issues because of their ability to absorb more bumps and shock.
As tandems often carry 150-250kg worth of bike and rider, hard wearing tyres are really important. We have had the most success with Schwalbe tyres (Mondial, Supreme or Dureme) because of their exceptional durability and puncture resistance, but Vittoria, Panaracer and Continental make some suitable tyres for tandems.
For my comparison between 26″ and 700c wheels, please click HERE.
- Suspension Seatposts
Suspension seatposts are really important for rear tandem riders on roads which are of a low quality. Unlike the front rider, a rear rider is not able to anticipate bumps. When a bump suddlenly occurs, it really hurts! It is best to do everything you can to make the rear rider happy because tandems aren't as fun without them!
The best suspension seatpost on the market is the Cane Creek Thudbuster, which uses an elastomer to absorb any shock from the road. It employs a parallelogram design which doesn't change the cyclists saddle height when active, a common problem amongst other suspension posts.
Given that tandems are so fast, most tandemists want lots of top end gears. But tandems can also require lots of low end gears – a balance must be struck.
Road tandems will require more top end gears than off-road and loaded touring tandems because of their high power to weight figure. I recommend gearing at 10% harder than a solo road bike if your tandem will mainly see flat roads with the odd hill. For those who are keen to ride any kind of road, you will do well with the same or 10% lower gearing than a solo road bike. Road triple cranksets which have a wide gear range and drop down to a 30t front ring, can be perfect for going fast and climbing!
For any other tandem (MTB and touring tandems especially), I recommend about 18 gear inches as the lowest practical gear – this is the same as using the smallest gear on a triple MTB crankset and cassette (24t x 34t). In this gear Kat an I can ride at 4-5km/h if we need to; any slower and we'd be better off walking. You can calculate gear inches HERE.
For information on Rohloff hubs and tandems, scroll down.
Tandems often carry two or more times the load of a solo bike, so you're going to need powerful brakes. I recommend the use of disc brakes on all but the lightest weight road tandems.
Rim brakes work fine for road tandems and touring tandems that are sticking to the pavement. For bike touring in remote areas, I usually prefer to use rim brakes, as spare parts are available almost anywhere in the world and they are less susceptible to damage – but on a tandem my opinion favours raw stopping power.
There is talk that dragging your rim brakes on a tandem can heat up the rim so much that the tyre blows out. Although this has not happened to me, rim brake users should be careful on long descents – take a break from time to time!
You can read everything about brakes and touring HERE.
The best v-brakes can be powerful, but they hold nothing compared to disc brakes. Stopping 150kg on a dime really takes a good set of anchors, and disc brakes are the best out there for this.
On a loaded touring tandem that is going off-road, I especially recommend the use of disc brakes. Our current setup includes one disc and one rim brake (when we purchased our tandem, we didn't have a disc-ready dynamo hub) and after riding in mud, water and down slippery, rocky descents – we will change our front brake to disc when we can, despite the fact that spare parts are harder to come by in many remote locations we travel to.
Some manufacturers claim that they cannot create a fork with enough flex (comfort) that is disc ready. We believe that being able to stop well with a slightly less comfortable fork is more important.
Disc brake brands that I trust and personally use are Shimano for hydraulic (XT or Saint), or Avid for their mechanical (BB5 or BB7). I have never found Avid to make a good, reliable hydraulic brake. Also note that it is important to use 8″ rotors on tandems because of their ability to cool as well as stop quicker.
For the down-low on brakes for touring bikes, read my article on brakes HERE.
- Tandem Timing Chains, Chainrings and Cranksets
There isn't anything particularly special about timing chains other than the fact that you will need approximately one and a half chains to make it work.
Timing chainrings must both be the same size to give a 1:1 ratio which will allow both the front and rear cranksets to be in phase. It is advisable to use largish chainrings of between 38-44t because the smaller the chainring, the harder the chain pulls (to make up for the fact it is not moving as fast) and the quicker everything wears out.
Timing chains normally run on the non-drive side of a tandem, but you can run timing chains on the non-drive side too. The advantages of running it on the drive side include being able to use conventional cranksets which are often cheaper and come in a range of sizes, and it keeps the greasy chains to one bike side. The disadvantages include the greater challenge of spacing out chainrings, and the fact that you may be limited with shifting options on derailleur gear systems. It is most common to see a drive side setup with an internally geared hub like a Rohloff.
It is possible to use Gates Carbon Drive as a timing belt. This will save you about 250g over a chain and chainrings. In order for Carbon Drive to work on your tandem, the frames boom tube must be 724mm between bottom brackets and you will need to use 130bcd cranks. It is possible to run Carbon Drive on both the drive and non-drive side of your tandem.
- Crank Phase
Tandems are traditionally set up to have the cranks/pedals in the same starting location for the front and rear riders. It is also possible to have the cranks out of phase (eg. 90 degrees out) which some riders feel eliminates the 'dead spot' in the pedal stroke.
We have tried our cranks at different phases and feel like in-phase is best; it's best for starting, best for balancing while riding, best for cornering and best for coasting!
- Rohloff hubs on a tandem bicycle
Rohloff hubs are perfect for tandems! Rohloff make a tandem hub kit (T) which comes with tandem length cabling, although there is nothing special about the hub itself. For the best results, use a tandem specific frame with a Rohloff dropout and two eccentric bottom brackets (or one eccentric and sliding dropouts) to adjust the chain length.
Rohloff hubs are available in either 32 or 36 spoke hole. Given that the Rohloff hub flange is so large, the wheel is 'dishless' and the spokes are so short, either spoke count will serve your tandem fine.
The minimum gear ratio you can run on a Rohloff tandem is 2.5:1. We ride with this ratio (50t on the front and 20t on the rear) and in our lowest gear (18 gear inch) this allows us to ride at 4-5km/h up really steep hills. We are able to chug along at 45km/h in our top gear (95 gear inch) if given the opportunity. If you are riding your tandem on flat roads, you will most likely want your Rohloff gear ratio to be 3:1 or above.
For a comparison between standard cranksets and Rohloff hubs, this page from the manual shows that having a 22t-32t on a derailleur drivetrain is the same low gear as 40t-16t on a Rohloff. Likewise, a top gear equivelent of 54t-12t is achieved on a Rohloff running 50-16t.
Rohloff recommend the using a Rigida Andra 30 rim for 26″ wheel build because the rim holes are drilled on an angle. This allows the nipple to protrude at a straight angle from the rim which in turn reduces any stress to the spoke, nipple and rim.
For more Rohloff tech info, check out '15 Reasons why you should ride Rohloff' and '13 ways to mount a Rohloff shifter with drop handlebars'
- Carbon Belt Drive on a Tandem
A Gates Carbon Belt drivetrain is perfect for tandems. The only prerequisites are that your frame needs to be Carbon Drive compatible and you will need to use an internally geared hub (Shimano Alfine or Rohloff).
If you haven't heard of Carbon Drive, the reason we like it is that it is silent, lightweight and maintenance free. For the full low down on Carbon Drive, read my article 'Carbon Drive: Everything you ever need to know'.
We have found that the Gates Centertrack kit is leaps and bounds better than the CDC/CDX type, as outlined in our Carbon Drive post. We currently run a CDC timing belt, but have found it's life to be short; we will be riding Centertrack soon. If you're going Carbon Drive make sure you're on Centertrack for both belts!
Those with derailleur drivetrains can also benefit from a carbon timing belt if your frame has been designed around the right distance between bottom brackets (724mm). This will save 250g from your existing tandem!
My megapost on 'Carbon Drive: Everything you ever need to know'.
- Independent Coasting Systems
On a standard tandem, both riders pedal at the same time, so when one rider wants to rest, it means both riders must rest. Independent coasting systems change this, by promising to make starting, stopping and cornering easier, as well as allowing riders to take independant breaks at times which suits them.
We didn't feel this was necessary for us, but it is worth noting that a company called DaVinci Tandems make bikes around this concept!
- Tandem bikes for families
There are a few companies making tandem bikes for families. Co-Motion, the manufacturer of our tandem make a series of bikes called the 'Periscope'. The premise behind them is that the rear seat tube is really small with an adjustable seatpost. This allows young children as small as 1.00m and adults alike to be able to be a rear tandemist on the same bike!
Other designs include: Onderwater tandem
- Folding tandems
A few companies make folding tandems – perfect for the space concious (such as caravan owners) and regular public transport users. Although wheels smaller than 26″ are not our style, we can appreciate that for some people a folding tandem is the perfect tandem!
Check out Bike Friday and KHS for more.
- Splitting a tandem into smaller pieces
It is possible to get a tandem frame down to the dimensions of a 26″ wheel! The most common way to split a tandem is using stainless steel S&S couplers. Co-Motion splits their frame into three pieces (four to six couplers) whilst other tandem manufacturers choose to split their frame into two (two to three couplers). Couplers do not decrease the frame strength or stiffness – they increase it!
Other manufacturers have their own techniques for splitting frames, such as Richey with their 'breakway' kit and I have seen a handful of custom jobs completed by frame builders.
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