lightspree

The carbon frame does not provide for mounting a water bottle cage under the down tube, near the bottom bracket. I am trying to put a water bottle cage there. The cage will hold larger than usual (1.5 liter) water bottles, and the bike will be used for long distance touring, some of it offroad. So it needs to be mounted well enough to handle the extra weight and stress. (The cage is made to handle 1.5 liter bottles.)

Can you suggest approaches to accomplishing this?

dsbrantjr

Here are some suggestions:
https://recklesscognition.wordpress.c...ws-and-bosses/
Adding Water Bottle Cages to Bicycles without Braze

lightspree

Where cage mounting bosses are not present, just bare CF tubing?

Clamps are apparently not a good idea (or maybe there are ways of using clamps with CF?).

What are some other options?

Andrew R Stewart 

Well having used both under the down tube cages and 1.5 liter cages for many years I have some opinion.


The first and strongest is that very few cages are designed to handle the force direction that the under DT location places on the cage. This location stretches most typically shaped cages apart. So strongly consider using a strap to secure the bottle to the DT, the cage only then handles the jiggling side to side and slight sliding along the tube forces.


The second is that of clearance between the bottle, the rings and the front tire/fender. But this is easy to account for, or at least figure out prior to a point of no return.


Third is that the vast majority of bottle bosses are not designed to resist a pulling out of the tube force direction. I've replaced a number of carbon frame bosses (located on the ST or DT in traditional locations) and the rivet like action even with epoxy places all the strength of the fitting in a compression or shear and not a tensile direction.


I will be interested in the further posts and the OP's end results. Andy.

Andrew R Stewart 

I'd not yet seen this site. Very interesting but no direct inclusion for the greater weight/size of a 1.5 bottle. I do take issue with the comment about hose clamps being a nono. I've ridden many tens of thousands of miles (since the mid 1970s) using TA handle bar cages secures by hose clamps, on many different bikes. Like any tool or device some sense is needed to do the right job. But to dismiss a solution that can work well so black/whitely is disappointing. Andy.

fietsbob

Two Fish a combination of Velcro straps and a rubber Block pressing itself down and not slipping..

Twofish Unlimited - Bicycle Accessory Fasteners







'/,

Tourist in MSN

You could call Velo Orange and ask them if there is any reason to not use these straps on carbon?
VO Bottle Cage Clamp - Water Bottles & Cages - Accessories

But currently out of stock. Not all cages work with those straps, they need a tab to go under the strap. In the 70s and earlier, all bottle cages were attached to bike frames this way.

I wanted another cage below my downtube on my rando bike (steel frame) for a container I use for spare tube, tools, etc. See photo.

BigAura

It's hard for me to believe that there's any chance they would yes. AND if they did I would still never do it. Carbon tubes are easily crushed and in fact they have had to redesign shop stands to accommodate this weak point.

rm -rf

Is this a vintage carbon bike, or a track bike? I'm surprised it doesn't have two bottle cage mounts.
EDIT--I see you posted in the Touring forum (I browse the New Posts), are you looking for a third cage?

Post a photo of the frame tubes. You can click "go advanced" and click the paperclip attachment button to upload from your PC.

FBinNY 

Because a below the tube mount would place the bosses in tension (pulling straight out from tube), I'd be leery of any riv-nut type solution. Of course you could use 2 straps to take up the load, but even then you risk damage to the frame from a pull out.

There are some strap or band mount "bosses" that may suit your needs, but even then, I'd use a smaller bottle below the tube, and carry the larger one above.

lightspree

Thanks for the responses. At this point the frame has two sets of factory installed cage mounts, in the usual locations. The third cage will be going under the down tube, near the bottom bracket (as in the picture in post #3 above), and it will be a Blackburn cage designed to hold a 1.5 liter bottle. So it needs to be secure enough to handle the extra weight and stress. And it should be a design that doesn't cause problems with the carbon tubing, which might arise from stressing it with the wrong sorts of clamps or straps.

(Might be able to send a picture when I'm back home with the bike.)

gsa103

What about using a CamelBak or other bladder in a different location?

Any RivNut solution for carbon frame is likely to tear out. So basically you can zip tie a bottle cage, but the cage will probably break.

Retoocs

Riv-nut will fail, just a matter of time.

If you didn't care about the warranty of the frame, I would make a doubler with nutplates and bond them on the inside if you can get in there. Or doubler with a threaded stud sort of like what Calfee does.

Tourist in MSN

Do you know with certainty that a 1.5 liter bottle would fit down there?

I have used some bottles that are close to a liter on conventional steel frame touring bikes, but used a velcro strap at the top of the bottle to hold the bottle close to the downtube so that the bottle did not touch the front fender on bumps, etc. A 1.5 liter bottle might be a bit big down there. See photo. (This is a different bike, different cage mount.)

If you do strap it on the way I did in the photo I posted in the previous posting above, it is not clear from the photo but I have the cage turned slightly to the left so that it is not centered on the frame, that is to avoid any chain interference when shifting. Keep that in mind when you install it.

Ty0604

I used some simple zip ties to add a 3rd water bottle cage to my Fuji frame. They held during the entirety of my 5,177 mile tour this year. Carried a few extra in case though.

Tried to upload a photo but can't seem to find the upload from computer option. Only the link option

alathIN

Hose clamps on carbon? Since the 1970s?

FBinNY 

Hose clamps are perfectly OK for CF frames. Other than the the works they apply very uniform circular compression, so they're near ideal to the task.

However, there will be some stress concentration and possible distortion under the works, so a pad or properly formed load spreader can't hurt. All in all, even without protection under the works, they're still OK as long as you don't go nuts tightening them.

Andrew R Stewart 

Well, not on carbon. Although carbon as a frame material is pretty old. But I think you missed my point about the linked web site dissing hose clamps. My point is that they can work well when dealt with well.


But this thread is really about the limitations of carbon fiber as a frame material. It wants design specific creation in the current era of less is more. Many here have said that the addition of a huge bottle cage (with a lot of weight pulling on it's mounts in a way that top of tube locations don't) is a bad idea. heed our collective wisdom and don't quibble about tangential details that were not the intention. Andy.

HillRider

I believe this thread illustrates rather nicely why true touring frames are rarely (almost never) made of carbon.

alathIN

I agree with you.
I have one alloy, one carbon, and one steel bike that I intend to keep (and a couple more laying around I need to get rid of).
So I'm not married to one material over another.
But this is a real limitation of carbon. The good news is, that it's custom engineered to be strong where the designers anticipate loads and light where they don't. The bad news is, if you encounter or create a load the designers didn't anticipate, all bets are off.

My carbon frame is a Tri/TT bike, which would generally be one of the uses you'd think carbon would be ideal for, but it happens to have only one bottle cage and that's in a location I do not like. I have access to a full machine shop and could easily drill some holes, make some threaded bosses, and bond them in there. But I'm just not excited about making two extra holes in a carbon frame that the original designer wasn't planning for. For all I know, there's a critical layer right there that will be fatally compromised if I put two holes in it, or put a couple pounds of off-center weight on it.

This is also why my touring/commuter bike, which has all kinds of things hung off of it that the designers never imagined, is steel.

And absolutely, I would never diss hose clamps. If I got rid of all my hose clamp redneck contraptioneering, my house and both my cars would probably fall apart on the spot.

Apologies for the major thread highjack.

RoadLight

Hi lightspree,

I think it's a bad idea. It's a bad idea because you have a composite frame that doesn't have the third set of bosses where you want them. And it's a bad idea because you will be doing "some of it off-road". You should look for another solution that doesn't involve adding an extra-large water bottle cage underneath your down tube.

Most "long distance touring" riders who need to carry extra water also need to carry extra other things. They usually have racks and panniers. Some also use the large Alaska-type packs that attach beneath the seat and extend back over the rear wheel. If you are using any of these, I suggest you find a place to stow your extra water there.

Regarding composite frames, there is a lot of misunderstanding about them and some of the least knowledgeable have the loudest opinions. A composite frame made for the purpose you intend to use it for is one of the best choices you can make if you budget allows. But to take a composite frame that was designed for another use and attempt to re-purpose it for long-distance touring is a bad idea.

The reason the tubes of many composite frames do not handle compression is because they were not designed for it. It is not a defect in the "carbon". One of the amazing properties of carbon composites allows a frame designer to make a frame strong where it needs to be and allow it to be weak where it doesn't need strength in order to save weight. Many composite frames are made this way in order to make them as light as possible while still serving their purpose (such as a road climbing bike). A good frame designer could easily design a composite frame to handle compressive forces. Just look at other composite components like seat posts---they are designed to handle compression with no problem. My FSA K-Force monocoque composite carbon seat post can handle plenty of compression because it was designed for that. (And independent tests have shown that the K-Force model with the 25 mm set back is still one of the best seat posts on the market at damping unwanted vibration.)

We don't know what kind of bike you have and what it's composite frame was designed for. You didn't even say what category (city/commuter, touring, general road racing, cyclo-cross, TT/tri, general mountain, downhill mountain, etc). All you've said is that it has a composite frame and you intend to use if for long-distance touring. Last time I checked, there weren't many carbon frames designed for this.

But regardless whether or not your frame is designed for touring, it doesn't have water bottle cage bosses where you want them for a third cage. So, unless the manufacturer of your frame planned for this kind of load, strapping it under the down tube is a bad idea---especially off-road. I think you'd be better served to find a different place to carry your 1.5-liter bottle.

Kind regards, RoadLight

Sy Reene

I'm just curious. With long distance touring, do you guys really cycle straight (without a pause) that you couldn't just stick an extra bottle (ie. the third) in the panniers. I'm not even sure how you folks can reach under a down tube to remove the bottle while moving. Very dextrous.

BobG

SKS makes a tidy looking adapter made of nylon and plastic. Fits tubes up to 1.5 inches...

ADAPTER ? SKS-Germany

https://www.amazon.com/SKS-Bottle-Ca.../dp/B017WOQRTO

Andrew R Stewart 

On my touring bike the third, under the DT, cage is for the stove fuel bottle (not what is a good thing to pack near clothing or food in a pannier). The 1.5L cage mounts to the seat tube. And depending on which touring bike it is on it uses either 3 or 4 bosses to secure it. Andy

Andrew R Stewart 

"My FSA K-Force monocoque composite carbon seat post can handle plenty of compression because it was designed for that. (And independent tests have shown that the K-Force model with the 25 mm set back is still one of the best seat posts on the market at damping unwanted vibration.)" RoadLight


I'm no engineer but I suspect your post's damping is more about it's bending then it's compression. But maybe it angles forward just enough to offset the set back so maybe it's really is in compression. Andy.