Beefy Touring Frames - Why is the accepted wisdom valid?
 

Hi folks,
The accepted wisdom about touring frames is: (thx Mtnroads) "First of all, a loaded touring bike generally will have a stronger, heavier frame and wheelset, frequently with 36-spoke wheels, to carry the weight. " Why is this true about the frames & tubes? I weigh 250, and am considering unsupported touring. Do lighter frames really break down under the weight & conditions? Is it about stiffness and transfer of power? Is it about handling?
Are touring frames generally over built or not? For me it's not about the weight as it is about cost and utility.
I'd like to see some real world experience in any replies.

Thx
CJ

In general, it's more about handling and stiffness than "breaking" (although that does happen).

Yes, I have some experience with this. I just posted on another thread about it (see http://bikeforums.net/showpost.php?p...&postcount=35).

Under certain conditions, this sort of flexing or twisting of the frame becomes a very real problem. I've ridden a variety of bikes, and those with beefier tubing can feel much more stable and controllable. It is not an all-or-none sort of thing -- there is a spectrum or a continuum. Some bikes are truly horrible. Smaller-diameter, lightweight tubing contributes to flexiness. Heavy loads also contribute. Less-than-rigid racks or rack mounting makes things worse. Weight that is higher rather than lower also aggravates the flexing. And other factors can also contribute.

The flex I am referring to is torsional and side-to-side.

Some bikes are so-so -- not so bad, not so good. And a few others are excellent. They really stand out, and do much better. Very little side-to-side flexing action.

If you go to downtheroad.org, and scroll down, and watch the left side of the screen, you will eventually come to a list of subsections on the website where there are some equipment reviews and discussions. Somewhere in there, Tim Travis (6'5" and about 230-240lbs) discusses the frames he has broken.

Heavier, stronger guys definitely need to consider frame strength. You can much more easily flex the frame, and more easily break the frame. Bikes are made to be as light as possible, while still being strong enough to last -- for a given rider and load and stress level. Many companies have special bikes (built with heavier, stronger tubing) for those over 200lbs, or even over 185. Bruce Gordon refused to sell a bike to Tim Travis. Other companies will accommodate with beefier frames.

I've heard of hard-riding 350lb guys breaking bikes quickly. Some riders, even in the same weight category, are more aggressive and abusive, and this plays a major role in longevity of equipment.

Touring bikes (520 stell, beefier wheels, etc) are generally accepted as the best bet for us uberclydes. I've definitely had issues with my mountain bikes, but have yet to break a frame. Mostly I just destroy bottom brackets. I'm riding a Randonee now, and it feels great. Doesn't accelerate as quickly as a stiff aluminum frame, but feels more solid - if that makes any sense.

BTW, plenty of 350+ pounders are getting lots of miles out of many different bikes out there. It can be done!

I've toured on a Cannondale cyclocross bike with no problems.
I suppose an overbuilt frame would last longer but I've had the Cannondale since 1996 and it's end isn't in sight.
I guess that proves that a frame can be light AND strong.
A touring bike is supposed to be nice to ride because it isn't twitchy. It takes less concentration to keep on course letting you pay more attention to the scenery. The long chainstays are one of the reasons for this with the added benefit of moving the panniers back away from your heels. A touring bike has all the brazeons for racks and fenders too.
The Cannondale has drilled dropouts front and rear for racks OR fenders but not both and brazons on the seat stays and lacks only the brazons on the fork.
It has short chainstays but I do not have a problem with heel clearance.
There are no handling issues. A loaded bike will ride pretty steady even with short chainstays.
There's no shimmy, wobbles, tank slappers, or anything like that.
The frame is light but it has a huge downtube, bigger than just about any other bike.
The ride is sweet because I use the fattest tires that will fit with only just enough air in them.
But, for touring, I would prefer to have a steel touring bike. For the long wheelbase but, really, for the aesthetics.
I weigh about 195 lbs.

It depends what you mean by touring. For hostelling across Europe, a race bike is more than enough. If you want to ride from Alaska to Chile then you need something heavier duty. US touring bikes seem to emphasise their expedition qualities but club touring bikes are a good midway style.
Many mid-range race bikes are plenty strong enough and stiff enough for touring (but lack clearance and braze-ons), it is at the ultralight end of the spectrum where you get problems.
One problem with lightweight race bikes is the thin tubing of the seatstays. They can't take much side-to-side stress from a heavy rear rack and can fail. Shot-in style stays are particularly vulnerable.

I've toured on a bike with a flexy frame. It wasn't much fun as I had to spend a lot of energy keeping the bike going in roughly the direction I wanted to head. By contrast my LHT handles a significant load quite well and rides fairly normally on tour.

I wasn't really worried about breaking the flexible frame - I just didn't enjoy riding it a whole lot.

I have a large (26.5") touring frame with 1" tubes. I've had it for 15 years and taken several long, heavily laden tours. Nothing has broken on the frame, and there are no signs of anything breaking. The problem is that when I'm carrying a full load and get going fast, the thing starts to shimmy badly. It's unsettling, and the panniers have actually been shaken so much that the corners got whipped into the spokes and holes were rubbed into them.

The wheelset, on the other hand, is prone to breakage if you're heavy and carrying a big load. I'm 215 lbs. and carry full camping gear, including cooking stuff. I've broken lots of spokes. Before my last tour I went to my local bike mechanic and told him to build as close to a bombproof wheel as he could. I probably spend more on the wheel than the rest of the bike was worth, but it was worth it. I didn't break any spokes on that tour (Oregon and California coast.)

One other good thing, if you're using panniers, is longer chainstays. My big (size 14) feet tend to hit the panniers. With long chainstays and the panniers set back on the rack, this isn't a problem.