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Tandems are hard on wheels. A tandem's rear wheel must carry twice the load compared to that of a single bike, and even many owners of single bikes experience wheel problems. Therefore, tandem builders have increased the spacing of the rear dropouts ("hub width": the technical term is "over locknut distance" or OLD) to allow for a more durable wheel.
- Standards commonly seen on modern bikes
- Why should wider rear spacing increase a wheel's life expectancy?
- So 160 mm is better?
- How can I make 145 mm wheels last as long as 160 mm wheels?
- Are 160 mm wheels here to stay?
- I am a novice just looking for trouble-free wheels. What should I do?
- What most experts agree on
- Advantages of 160 mm rear spacing
- Advantages of narrower rear spacing (145 mm and less)
- Advantages of single-bike rear spacing (130 / 135 mm)
- Disadvantages of single-bike rear spacing (130 / 135 mm)
- Hub width makes no difference in respect to...
Standards
commonly seen on modern bikes are:
- 130 mm - most single road bikes since the early 1990s
- 135 mm - most single MTBs since the early 1990s
- 140 mm - many tandems until the late 1990s
- 145 mm - tandem "standard" since the late 1990s
- 160 mm - introduced by Santana in the early 1990s, also used by Longbikes, Meridian, and others.
It WILL not, it MAY! But read on: Rear wheels are plagued by problems because the drive-side spokes must be at a steeper angle than the spokes on the left side to make room for the rear sprockets. A steeper spoke angle, however, reduces the side-loads the wheel can take (a wheel with a single row of vertical spokes would collapse instantly when confronted with side-loads!).
If the sprockets are moved further to the right the drive-side spokes can be at a shallower angle. The result is a symmetrical rear wheel. All other things being equal, this wheel will live longer than a standard wheel. Thus, if you compare a large number of 140/145 mm wheels and compare it to a large sample of 160 mm wheels, the 160 mm wheels will probably last longer. At least this is what Santana discovered: Their wheel problems diminished considerably when they moved to 160 mm spacing, and I believe them: Many (most?) bicycle wheels are built by less than competent wheel builders, and wide flange spacing allows for a greater margin of error. Thus, even poorly built 160 mm wheels will last some time, while poorly built 140 mm wheels will fail fairly soon.
So 160
mm is better?
Wider rear spacing comes with other
problems, though. As the sprockets move outboard, either the front chainrings
must be moved out by the same amount (leading to a wider distance between
the pedals (Q-factor), which many riders dislike and some cyclists fear
causes knee problems) or the chain will run at an angle. This will lead
to shifting problems with modern components gruppos.
Good wheelbuilders have no reason to go to 160 mm as 140 or 145 mm are wide enough to build a wheel which will not be plagued by breaking spokes. Santana's Bill McCready and other proponents of 160 mm-wheels will disagree with me here because they consider the wheelbuilders who built Santana's 140 mm wheels "competent", thus, if their wheels fail it must be a design fault ...
Their reasoning may be correct from the point of view of a businessman: Paying good wheelbuilders to build good wheels may be more expensive than achieving the same durability with a different design, but cheaper labor. Without a large field test I am in no position to answer that.
How can
I make my wheel last as long as 160 mm wheels?
You should not be satisfied with
a wheel which lasts as long a typical 160 mm wheel - yours should last
longer! If you choose the right components for your application and the
wheel is built correctly, you should not suffer breaking spokes for the
lifetime of the rim!
- Using an asymmetrical rim as offered by Ritchey or Bontrager can make a wheel (almost) dishless.
- Use high-quality, double-butted spokes (2.0/1.8/2.0 mm spokes suffice for most purposes, the DT Alpine III (2.3/1.8/2.0 mm) is recommended for extreme applications)
- Make sure you are using high and even spoke tension, your spokes are not wound up, and learn to stress relieve the wheel properly. The book "The bicycle wheel" by Jobst Brandt will tell you all you need to know.
- If you have a STEEL frame you can have your rear triangle spread from 135 mm to 140 or 145 mm. Tandem rear triangles with their oversized tubing are much harder to spread, and it is hard to get it exactly right, so it pays to have a framebuilder do this modification. Spreading to 160 mm requires major modifications (new brake bridge etc.) and a repaint.
160 mm wheels are certainly a success story as far as their marketing success is concerned: Arguments comparing numbers seem objective and are easy to explain to customers. The advantages of 160 mm hubs are obviously an argument many tandem buyers (who have no way of judging the quality of a wheel) believe.
I am a novice
just looking for trouble-free wheels. What should I do?
If you are looking at your first
tandem to buy, do not pay too much attention to rear spacing. I would only
stay away from 135 mm spacing. More importantly, ask if the manufacturer
or the dealer will give you an unconditional two-year warranty against
spoke breakage on your wheel. Let them give it to you in writing! Any competent
wheelbuilder should back up his work. If they don't, go someplace else.
If you still like the bike, buy it at a large enough discount to have a
wheelbuilder with lots of tandem experience build you new wheels with a
two-year warranty.
Let's sum up on what most experts agree:
- 130 mm is borderline for Campy hubs on road singles already
- 135 mm is strong enough for current singles, though more symmetric flange spacing would be better
- it will be hard to integrate 10+ gearing into 135 mm
- building a good 8/9-spd tandem wheel on a 135 mm hub is possible, but requires a very good wheel builder and careful attention when picking components
- nobody seems to build 140 mm bikes anymore
- 145 mm wheels can be symmetrical and they can be built strong enough for tandems
- it will be hard to impossible to integrate 10+ gearing into 145 mm without sacrificing some strength
- since they provide wider flange separation, 160 mm wheels theoretically can be built to last longer than 145 mm
- the advantage of 160 mm over 145 mm wheels built by a competent wheelbuilder is not easily proven in real life (Bill McCready disagrees with me here)
- asymmetrical rear triangles would be another option without forcing us to go to odd-ball hubs, but this approach seems to be out of favor with frame builders, as it makes fitting cantilever brakes and racks harder.
- Wider flange separation giving a greater spoke bracing angle, allowing for higher side loads
- Possibly easier to upgrade to more than 10 cogs in the future
- No need for asymmetrical rims
- Use of single bike hubs with longer axle possible (this would lead to a reverse asymmetrical rear wheel if done with 160 mm)
- lower Q-factor or better shifting or both
- Slightly more hubs available in 145 mm than 160 mm
- Single-bike hubs widely available
- Rohloff Speedhub-compatible!
- very durable if used with asymmetrical dropouts
- Single-bike hubs often not strong enough for tandem duty
- Greatly reduced lateral stability if used in symmetrical rear triangle
- Compatibility in case of a mishap: Yes, a 160 mm and a 145 mm wheel cannot be exchanged. However, both "tandem standards" are about equally (un)common, so there is little reason to base your decision on what everybody else does. This is not a Beta-vs.-VHS situation.
- Hub replacement problems far away from home: All tandem hubs are fairly uncommon.
- The necessity to pay a qualified wheelbuilder for good work: Poorly built 160 mm wheels still fail.