The Importance of Rack Rigidity

Pass & Stow

Rack rigidity and load securing are absolutely critical to bike stability and predictable handling. Far more than where a load is carried, a stiff rack with zero flex and a completely secure load are the biggest contributors to stable and controlled handling when carrying cargo.

A number of people have complained to me about loaded bikes handling poorly. In almost every case, the culprit was a weak, flexible rack, or a loosely secured load, both of which allow the load to sway, taking control away from the rider. This problem is particularly acute when loads are carried on the front fork. I know quite a few people who don’t like to carry a load on the front of the bike. I’m guessing that in a majority of cases, the underlying issue is a sub-par rack or mounting method, and that a sufficiently stiff front rack with a high quality bag would change their minds.

On my Surly Long Haul Trucker (which I use for commuting and cargo hauling), I run a Tubus Cargo in the rear, and a Pass & Stow up front. Both are made from tubular steel and act as completely rigid extensions of the frame. I can comfortably carry 75-100 lbs. on that bike with no issues whatsoever. I attribute this excellent performance much more to the racks than to the bike itself.

24 Responses to “The Importance of Rack Rigidity”

  • Elliott @ Violet Crown Cycles says:

    Excellent point. I’d add that fork geometry and to a lesser extent chain stay length contribute to the the degree of riding stability of a front loaded bike. I’d also add getting your load’s center of gravity as low as possible will help greatly as well.

  • Andy says:

    Never saw this as an issue, especially since cheap racks seem to be just as beefy. I bought some $20 rack on Nashbar 3 years ago and never had any issues with it. I even had it on my race bike the first year (no bolts on the seat stays, just plastic clamps) and it worked fine. I don’t get why chain stay length seems to be such an issue – is that only for huge bags? My first panniers had brackets about 4″ from the top of the bag, so I remounted them about 1″ from the top because I wanted the weight lower. I keep the bags close to the back of the rack and my feet never hit it.

    I should mention that I have yet to put >30lbs on the rack, but don’t plan too either. My full touring setup doesn’t require more than 20lbs on the rear rack. Maybe for overloaded ginormous panniers holding the kitchen sink, my rack wouldn’t suffice?

  • Alan says:

    @Andy

    Since you’re running light loads, even a marginally stiff rack should suffice. It’s only when you start hauling 50-75 lbs. or more that it becomes a serious issue. I’m talking about groceries (including liquids) and home improvement type items that can be much heavier and more dense than items that would be carried on a tour.

    Regarding your chainstay question, besides large bags, large feet and long cranks also contribute to clearance issues. A combination of all three can be a game stopper on many bikes.

    Alan

    PS – Just for the record, inexpensive aluminum racks are not anywhere near as strong/stiff as brazed tubular steel racks.

  • Pete says:

    “On my Surly Long Haul Trucker (which I use for commuting and cargo hauling), I run a Tubus Cargo in the rear, and a Pass & Stow up front. Both are made from tubular steel and act as completely rigid extensions of the frame…”
    In fact, the two racks together cost more than the frame! :-p

  • Jon says:

    Another way to really increase the rigidity of a rack is to attach your fenders to it. Lots of racks available today come with an M5 threaded eyelet on the underside of the platform for attaching fenders. They complement each other, and increase the rack’s stiffness, and also provide another point to mount fenders. The fender will vibrate much less, which means no rattling or cracked fenders! Hooray!

    Of course, it really works best/only with metal fenders. I haven’t tried it with the Esge/SKS laminated fenders, but it might work with proper washers, etc…

  • Michaelniel says:

    Some years back, I was running a Schwinn Fastback (road specific), to which I had Macguyvered a transit (Performance)rear rack to using pipe clamps from Ace Hardware. I thought it was great for a thousand miles or so. This was before dumping it twice at speed in the rain made me realize the benefit of a real commuting bike with a sturdy rack. Not only did the rack itself have quite a bit of flex, but of course the mounting system was less than ideal. Also, mental note: Don’t run 23’s on your commuting bike if you plan to ride it loaded in the rain :(. I now run an Old Man Mountain rear rack on my Jamis Aurora, and it’s been great…..doesn’t wander a bit.

  • Alan says:

    @Pete

    “In fact, the two racks together cost more than the frame! :-p”

    Ha! I guess you’re right! :-)

    Alan

  • voyage says:

    Seat post racks: yay or nay or it all depends?

  • somervillain says:

    Indeed, rack rigidity is important to the feeling of stability on a bike. Wald baskets are the worst in this regard, when mounted using their own hardware. That’s why the best way to mount a Wald basket is to a rigid rack.

  • Frits B says:

    Some time ago I found this report:
    http://james.architectureburger.com/cycle/cargo.html
    which I found interesting as this cargo bike much resembles the one built by Michael Kemper in Germany – which is very stable.
    Read the part about shimmy in the front wheel under loads, and how this could be remedied by putting the loads themselves on a flexible surface, thereby more or less reducing the rigidity of the rack. I have no idea what the explanation for this behavior could be (no engineer) but it illustrates the problems that might be encountered.

  • Alan says:

    @voyage

    My experience with seat post racks is that they’re fine for a light commute load, but not much more. Any heavier and they can twist/sway.

    Alan

  • Alan says:

    @somervillain

    I too like Wald baskets best when mounted to a stiff rack.

    Alan

  • Pete says:

    @Voyage
    I use a Carradice Bagman as both a support for a saddlebag and a mini rear rack of sorts. Though it won’t carry as much as the larger cantilevered racks I think you are taking about, I find it perfectly stable for lighter loads, and it does a great job keeping my occasionally overloaded saddlebag from bouncing around.

  • Adam says:

    I think that shimmy is about oscillation. When I used to have a handlebar mounted wire Wald basket, I could fit two gallons of milk in it. But the ride home…yikes. It literally felt like I had a small creature shaking the bars. However, one time I put a bungee cord around the wire rack and around the head tube. When snugged down it didn’t shake nearly as bad. I think that the number of points of contact can greatly affect the shakes a rack load has.

    Also I think we should remember that steel and aluminum both flex. Design has as much to do with flex as materials.

  • Alan says:

    @Adam

    “Also I think we should remember that steel and aluminum both flex. Design has as much to do with flex as materials.”

    True! That said, it’s also important to note that the very best heavy duty racks are all made from tubular steel.

    Regards,
    Alan

  • dnalgne wen akhsinak says:

    @voyage,

    carradice sqr is pretty amazing too. that what i use currently, but mostly because i’m on a folder. its such a strong mounting piece for a tiny mounting area.

    my current philosophy is a tradeoff between sturdy support and easy off bike carrying (alongside a folded bike). the most manageable setup i’ve come up with, after 2 years of folding, is a klickfix backpack mounted riser (or headtube if possible) mount and sqr seatpost mounted carradice in back. very poor quality photos (via cell phone): http://www.bikeforums.net/showthread.php/83711-swift-folders?p=11972370&viewfull=1#post11972370

    the xootr crossrack is good. used that for a while. it handled some enormous loads well.

  • Tim D. says:

    My commuter bike has a Velo-Orange Porteur rack up front. While the rack itself, with some bending and adjusting of the fork crown attachment piece, is perfectly stiff. However, I have noticed with heavy loads that my quill stem wants to twist and turn. This is of course with unusually heavy loads loaded up front, that I don’t normally ride with, even on weekend camping trips. It still makes me wish I had a threadless front end on that particular bike.

  • David says:

    I really like the rack designs on the Tout Terrain bikes. They’re tubular steel and integrated into the frame design with welded connections to the rear triangle. It doesn’t get any stiffer and lighter (for a given load capacity) than that.

  • Alan says:

    Hey David,

    I agree; the Tour Terrain rack systems look excellent. I’ve never ridden one, but I’ve heard good things. They sure look good on Peter White’s website.

    http://www.peterwhitecycles.com/tout-terrain.asp

    Alan

  • Alan says:

    @Tim D.

    While I usually prefer quill stems because of their ease and range of adjustment, you make a good point about the stiffness of threadless stems. I’m wondering now if I’d be unhappy with a quill stem if I had one on my cargo hauler.

    Alan

  • Joseph E says:

    Re: Aluminum vs Steel for racks.

    While an Aluminum bike frame can be plenty stiff, while still lighter than an equivalent steel frame, this is achieved by using very wide (high diameter) tubes. The small tubes usually used on front and rear racks cannot be made very stiff with aluminum.

    However, my wife has a Globe Live 2 bike, which comes with a front rack made out of relatively thick aluminum tubing (about 2 cm in diameter, almost 1 inch), and this is much stiffer than the usual cheap aluminum racks. Unfortunately, the tubing is too thick to fit most pannier designs, though this is less important with the design of the rack.

    For touring or heavy commuting loads, a stainless steel or good quality painted steel rack (such as those used in Europe) will be the best choice, due to the basic metallurgic characteristics of thin aluminum and steel tubes.

  • doug in seattle says:

    My camping bike was until recently equipped with a Surly “Nice Rack” front rack.

    At first glance, this rack seems to have it all: huge load limit, beefy design, high/low pannier mounts and a top platform. Super! I thought it would do everything I wanted in one relatively inexpensive rack (bought new off Craigslist for $70).

    After installing and using it, however, I realized it has some what are to my eye serious design issues. Its highly modifiable mounting design, while certainly versatile, is nightmarishly heavy. At least twelve bolts, with all the attendant nuts, washers, spacers, etc. bring the rack wright up to something like 1500g unloaded (the Tubus Tara weighs 500g, if I recall correctly).

    Heavy weight is never a deal-breaker for me: if something is durable, useful, inexpensive yet good, or in some other way nice, I will always overlook a heavy item. Particularly my camping bike which is often loaded up with a few dozen pounds of camping gear.

    The problem with the Nice rack is that, despite the overbuilt weight of the thing, it sucked. I hated it. While panniers mounted low posed no real issues, any weight on the top platform caused the rack to sway from side to side very easily. It apparently was not designed with lateral rigidity in mind, as it is not in any way triangulated. Compare it to a high end rack and you will see that it is triangulated. This is one of the reasons why the Tubus Cargo is so delightfully stiff.

    As a result, I had a rack that was heavy, flexy, and that had a serious negative effect on the handling of my camping bike. It was especially bad when the top platform was loaded, and since I got the rack specifically for the top platform, I had to ask myself if the rack actually met my needs. It absolutely doesn’t, and thus I sold it to be replaced by a standard low-rider rack.

    And that is my very detailed rack-stiffness testimonial. Conclusion: racks need to be STIFF.

  • Alan says:

    Thanks for the report, Doug. I agree, racks used for carrying heavy stuff must be triangulated and stiff!

  • EcoVelo » Blog Archive » Dirt Trails says:

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