gregw

Let me bounce this idea off the group. A custom framed touring bike that is designed to carry the load within and / or on top of the frame, but never wider than the rider. The Revelate Design company

https://www.revelatedesigns.com/index...=1&ProductID=6

makes custom bags to fit the interior triangle of your bike. How would you manipulate the frame geometry to maximize these potential storage areas?

For example, my touring bike is a 63cm frame with a tall seat post and a high handlebar riser. I could modify the frame with an extra tall steering tube and the top tube to extending upward to just under the saddle. This would create a very large main triangle that could be used to hold most if not all my load.

I'm sure it would look pretty goofy, but interesting just the same.

gregw

Ok, here is a crude photoshop photo of what I'm thinking about.

The areas in yellow used for storage, the front handlebar and rear rack are exaggerated but I was just showing areas. I think I could fit my entire kit in the enlarged main triangle area, with a regular handlebar bag. If I needed more space, I could add a trunk bag. All would be within the slipstream of the bike.

As big as I am on a bike, I'm sensitive to the additional frontal area that panniers create. Makes headwinds really suck. Packing this way distributes the load equally on the wheels and creates no additional wind resistance. Could be a very lightweight touring option.

Just an idea.

azesty

I understand your motivation, but see two problems.

1) your center piece is taking up the water carrying place, and easy quick access to water is important on tour, especially when it is hot.

2) You will have raised the center of gravity of the bike a fair bit.

z

drmweaver2

An additional problem is the amount of "sail area" in a crosswind!

NoGaBiker

Additionally, it's ugly!

gregw

Good points, about the water, as long as I can put in one water bottle on the handlebar, the rest could be in a bladder in the lowest part of the center triangle bag space. Just refill the handlebar bottle as necessary, good reason for a stop. This would also help the center of gravity issue a bit. Heavy items packed low, light on top. I weigh 225, with most of that above the seat line, so I'm the biggest factor to COG.

I'm assuming an ultra-light load in any case, sub 2lbs tent, down bag, all my lightweight backpacking gear.

gregw

Could be a problem if I filled all the yellow area with stuff, but if it's just the center triangle, it would be no more than using both front and rear panniers, I would think. Good point though.

I would think I could get the bike weight about 25lbs, with fenders etc. then add 20lbs for a touring load (includes bag, water and food).

Whole thing around 45lbs as a goal, I think it could be done?

gregw

Yeah, pretty ugly!

Might be better to use a standard bike and have two bags; one in the main triangle and one that Revelate Design calls their tank bag, which goes on top of the top bar. Two bags being less efficient than one, but then you don't need an ugly custom bike frame. Revelate will do custom bags to fit the exact space available, so that's probably the best way to go.

cyccommute 

Point 1: One word - Camelbak. If you've seen pictures of the mountain bike tourers, they carry very large Camelbaks for water and for the extra space they need.

Point 2: This is the real crux of the issue.

Although I am intrigued by Revelate's bags for overnight to maybe 3 day trips (and will probably purchase some later this year), they are bags that are built around bikes that really aren't touring bikes. They are built to fit on mountain bikes were you can't carry panniers as easily as you can on the road. And they are better than trailers. But they do move your center of gravity up and bicycles already have a high center of gravity.

Why not just get the bike weight down if you need it and run front panniers? It'd be cheaper and you get the advantage of dampening the front steering. A set of Ortlieb front pannier will easily carry 20 lbs of gear and they only cost $130. The Revelate bags cost around $450 for what you want. Now if you wanted to go off-road (which is fun and an adventure in its own right), I'd suggest the Revelate bags over a trailer any day

acantor

I doubt that the frontal area of panniers is a major source of aerodynamic drag, at least at low speeds. Drag is related to area, but it increases with the square of velocity, so any effect would only be apparent when bombing down a hill, assuming one's goal is to achieve maximum speed... which does not apply to me, anyways.

But at normal touring speeds, the additional air resistance due to panniers is not going to be a lot. The frontal area of your body is likely to contribute more to drag than panniers.

gregw

My experience tells me otherwise.

By the numbers, my rear panniers add 9" wide x 17" tall each (x2) = 306 sq. in.

My upright chest is approx. 15" wide x 20" tall = 300 sq. in

That's a lot of additional frontal area in my opinion. Wind resistance is the number one enemy in my opinion. If your on a 4 day tour, no biggy, but a 4 month tour and you care, or at least, I care.

Bacciagalupe

IMO this is a solution in search of a problem.

If you're carrying an ultralight load, a small backpack + lightweight rack + waterproof stuff-sack, possibly coupled with a handlebar bag, really ought to fit the bill. For further details check out this article from Adventure Cycling.

It's certainly not worth building a custom bike to maximize this type of baggage, especially since most touring bikes already use classic straight top tubes instead of sloping tubes.

On a side note, without going into a wind tunnel it's nearly impossible to accurately determine the aerodynamic effect of panniers. Different shapes, materials, seams, surfaces and location can all impact aerodynamics.

BengeBoy 

100 + bonus points to the OP for coming up with an interesting idea.

I think it' interesting to think about how bikes might be built differently in order to accommodate a touring load. In this particular instance, I would worry big time about raising the center of gravity so high; somebody with real engineering training could likely figure that out in a couple of minutes.

I've never considered the frontal area of front panniers to be a big deal at touring speed - if I were I'd be more inclined to think along the lines of an Extrawheel trailer.

gregw

I don't need a wind tunnel to know that if I doubled my chest area on the bike, it would make a big difference. I have done side by side testing with full panniers vs BOB trailer and the BOB wins every time. Problem is the BOB adds a lot of weight and length to the bike.

gregw

Thanks for the Bonus points, can I cash them in at Nashbar?

Yeah, consider the photo in the post above, if you extended the top tube up to just under the seat, it would almost double the capacity of the frame bag.

The thing about the Extrawheel, is that it's just as wide as regular panniers on your rack, so I don't really see the advantage. The BOB keeps the whole load much more narrow.

I have a design for an ultralight, single wheeled trailer, that is about 16" shorter than the BOB and should weigh about 3 lbs. Just have to figure out how to make it : )

GamblerGORD53

You must be very tall, because the frame does look like it could be 2" higher and longer. No need to go as high as the seat.
Use normal step-over. You can put water bottles partly behind/beside the forks.They would help lower the CG also.
Then have a bag in front of the headtube. Then maybe use two medium rear paniers for the heavy stuff and the bedrolls on top. BF Member 10wheels has something similar. The bags those guys make are way narrower than they could be.

I have been thinking the same things. Just for the hell of it, last April I made a prototype out of cardboard. My bike has a useless little hybrid frame. So anyway i took off one bottle holder. The box was only 16" long, 3" by the seat post and 5" in the front. Then i filled it with 8 tins of food , 7 lbs, and tied it in. It was cold , so it was a short ride. It felt like a brick and made the shocks groan. haha Only the top corners bothered my legs and it did feel top heavy when getting off.

unterhausen

look at the rigs from the Great Divide race, a number of riders think similarly to this. I suspect that you would definitely hate yourself if you take it to the extreme shown in your mock-up. We often don't even notice cross-winds and they would be a big problem, particularly with the big bag in front. The main triangle bag would be a good basis for a very lightweight touring setup.

nun

A sport tourer with flat handlebars would work. Lots of room inside the triangle and you could fit a handlebar bag and a rear saddlebag. Of course you still have the stuff sack drawback of always wanting whats at the bottom of the bag.

I like the idea of using the space inside the triangle for more than just water. It's good that it's close to the center of gravity of bike and rider, buy I still wonder about side winds and leg rub.

ploeg

Practically all of the front-facing surface area of rear panniers sits directly behind your legs. The amount of front-facing surface area that is directly hit by headwind is minimal.

cyccommute 

You say above that you aren't worried too much about the high center of gravity and how it affects the bike. You should take the same attitude towards the panniers. Your surface area has a much more drastic effect on drag than the panniers do. You are forgetting your head, arms, lower torso and legs as well as the bike in the above calculations. The drag from those adds up to more than what your bags do.

I'd go further and say that the bent over position of a cyclists might create more drag because of the cup that your chest/arms/torso form. This is going to trap air that is flowing around you which would resist even flow of the air. A relatively flat surface like bags are going to allow for a bit laminar airflow around them than the human body would.

Further, bags that fill the bike's triangle are going to create their own problems. If you could make bags like your picture, you've created 3 sails that are going to be a bugger to deal with in a crosswind or even a wind that is several degrees off of your direction of travel. A car rushing past...not something you run across a lot while off-road touring...might even cause problems with it bow wake. A truck could blow you straight off the road

Ruffinit

I've used the triangular bags (TT/ST) that have shoulder straps, and the front triangular bags (HT/TT/DT) for smaller stuff and they're fine for small stuff. As ploeg stated the rear panniers being directly behind your legs capture negligible wind. All these bags catch side winds and a full triangular bag would be a great sail. Combine that with the leg rub and the issues with packing so that you wouldn't get a bulge out of the bag for foot strike... and as you say, a couple days would be a nuisance, but a longer tour would be a real pain in the backside. I've touched my knees on my TT and kicked a bottle that wasn't properly in the bottle cage.. think of that bag sitting between your legs. (no, not that bag)
I use front panniers when I don't need the capacity of the rear panniers. I note more drag from a single handlebar bag than from the front panniers. Rear panniers don't seem to be affected unless it's a side wind. So I guess if I were worried about headwinds on a tour, I'd go with a set of rear panniers and a trunk bag. (aero bars / TT helmet) I can't think of the mfg, but one company used to make a front pannier that was curved on the leading edge.

gregw

Lighten up dude, Your twisting things all around for no apparent reason, other than to be contrary. Go for a ride you'll feel better, promise.

dscheidt

You're the one worrying about the non-existent problem of increased frontal area of rear panniers.

rodar y rodar

1. So, what?
2. Maybe. You can say it isn`t worth it to you, but I think it would be a very interresting experiment and if the OP has the means to do it it may well be worth it to him. Even a "failed" experiment is worth something.

GW, have you considered smaller wheels?


What would your mockup look like on a Dahon Smooth Hound?

Bacciagalupe

So, it's a counter-productive idea. In his quest for reducing frontal area, he'd make a bike that will get blown over in a crosswind, will handle terribly due to raising the center of gravity, and will be potentially too flexible for its purpose (due to the larger triangle sizes).

Believe it or not, there are actually good reasons why touring bicycles don't look like this:






I see. How much time, energy and money should one sink into an experiment that, even on paper, generates numerous issues?

Granted he could, for example, take these comments and learn that frontal area isn't everything. Or perhaps someone will recommend he just use small bags and perhaps even a fairing. But you don't have to build the bike to realize it's unlikely to work for its intended purpose.


Or, to put all this another way, the OP is opening his idea up to criticism. I and a few others letting him know the problems he's facing -- but also pointing him to potentially beneficial alternatives.