GlennR

So on a downhill I hit a section of rough road, 100 yards later I hit another section, but this time I head a rattle/buzzing sound after. A short time later i hit a 3rd section and the water bottle on my downtube went flying. Since I was on a group ride and doing over 20mph, I just kept on going. Later we stopped and I noticed the water bottle cage was loose. Worse yet the M5 bolt on the bottom snapped off, leaving the remainder of the bolt in the bung. Now i'm concerned how to remove it without damaging the carbon frame or the bung. Worse yet, the bung is inset about 4mm into the frame. On the way home I stopped at the LBS, where I bought it, and showed it to the mechanic. We discussed how to get it out without damaging. I said i have a set of "left hand" drill bits and if we used a variable speed drill and the small 2-3mm bit I bet it would spin out. So I headed home and left the bike. An hour later I returned and the bottle cage was already back on. He used a pick and was able to carefully unscrew it. He also replace the top bolt since it looked stretched. He said he never uses a thread lock to prevent the bottle cage bolts from coming loose for this reason.

So I guess a 20oz bottle might be too heavy... over time. Maybe I should switch to steel bolts.

Alias530

I trail ride my cross bike and have never lost one of the 25oz bottles I use... I'd say you probably have junky cages.

gsa103

Most like the bolt actually loosened a little bit, allowing the cage to rattle a little. The rattling will transfer more stress to the bolt than a rigid connection. No reason not to use steel bolts though, the weight difference is very small for 2x M5 bolts.

chaadster

What material were the bolts? I think there's little to gain not using stainless steel, but Ti would work; alu I wouldn't bother with.

EDIT: gsa103 beat me to it!

FLvector

+1 Most likely the culprit.

GlennR

Cages are Bontrager XXX carbon.

Agreed.... 2200 miles since the cages were installed and maybe they loosened. 99% of the time i only ride with a single bottle on the downtube, so it's in and out a lot.

The bolts are ally, I assume aluminum.

The mechanic replaced the other bolt since it looked a bit deformed and could fail.

Since the bike is a Trek Emonda SLR, the bottle cages are Bontrager XXX and came with the bolts, i'll be emailing tech support asking if they've seen this happen before.

And yes... the cages were installed with the correct torque.

ZippyThePinhead

I have an older steel Trek 560 which had a water bottle screw rust in place (it was that way when I got the bike). I had to use a Dremel to slot it before it could be removed, as the hex hole was stripped. So I typically put a bit of grease on the threads of those screws to avoid repeating that experience.

It isn't a bad idea to check the screws to make sure they haven't loosened from time to time.

Regarding bottle weight, I routinely use 32 oz bottles, and my cages are stainless (from Performance), so once in a while I will bend them so they exert a slightly higher force on the bottle sides. I've had a couple of ejections of these bottles while riding over bumps/potholes, and I'd hate to be the cause of someone crashing (myself or someone else). Can't be too careful.

Alias530

Hmm, no experience with these. And not to be a smart ass but just because they're expensive doesn't make them good

I've always used Elite Custom Race cages and they've been good. Contemplating a switch to Arundel for a little bling though. I've read nothing but good things about them.

Alias530

Kick ass, didn't even know they made bike bottles that big!

GlennR

True... they are very light and their website says they are NOT for off road use, so they're pretty up front about it.

I've ridden on a number of rough roads and never lost a bottle. But you're missing the point, the bottle was tossed because the bolt broke, not because the cage couldn't hold it.

BTW... I did go back and found the bottle sitting on the grass. It has a bit of road rash, but nothing a little soap and water won't fix.

Athens80

Does someone inspect the bike periodically to verify that everything's in order, like bolts still in place?

RShantz

I agree. I do gravel grinders and have never lost a bottle. Now I don't use the latest and greatest weight weenie cages. Will sacrifice a few grams for safety of the group. All of this is assuming the "junky" cages.

Alias530

I just looked up the XXX ones, wow they're light. 19g. I think mine are 40g. Mine are plastic while yours are carbon but still HALF the weight is impressive.

GlennR

I clean and service the bike every weekend, about 150 miles between and inspect everything. I never noticed the cage was loose. And if it was, i'd notice it the first time i removed the bottle and put it back.

GlennR

Since the bike is very light already (14 pounds 6 ounces ready to ride), I figured "why not" keep it that way.

TrojanHorse

Makes sense.

I stuck lock tite on mine, never had an issue. I have, in the past, had bolts work loose.

FBinNY 

It's relatively common for DT bottles to get ejected to the front when riding bumpy roads at high speed.

Every time you hit a bump it imparts a force on the wheel running from the point of contact up through the axle. That vector can be divided into 2 components, the vertical force that lifts the bike, and the horizontal force which ******* the bike. The taller the force the greater the ****** force is with respect to the vertical.

Now consider that there's a distance the bike must lift, which is the height less any compliance in the tire. So harder tires mean more height. Speed also plays a part because with more speed you have less time for the front end to rise, so the required G-force is greater. Since the ******/lift forces have a fixed ratio, fast hits on not so small bumps generate significant ****** forces, so the bike slows suddenly (more Gs than your brakes can produce) and the full bottle continues forward on it's own inertia.

There's a hill I ride in CT where the maximum speed is set by this effect. Ride it any faster, and you'll eject the water bottle almost every time. (not counting what it does to your body).

GlennR

My mechanic specifically said he doesn't use thread lock in case the bolt snaps. It would never come out even if it was only blue loctite.

I'll just need to check the torque every now and then to ensure it's correct.

79pmooney

Old school here. Water is first order important. I only use steel cages (now ss) and steel bolts. Currently my cages are the Kings. Haven't broken one yet but I doubt any have much more than 12,000 miles yet. (I like the ti King cages but at over twice the cost and probably less WB grabbing capacity being a less stiff material I'll probably stay ss fro a while. Besides they look quite OK on ti bikes.)

Those ss King cages are such WB grabbers that I have many times stuffed my bottles in quite crooked and not noticed until I reach down for my next drink and discovered it had been sitting very cockeyed in the cage the past 15 miles.

Ben

Up North

What did mechanic say to torque them too? I use 2 big camelback podium ice bottles in mine, same bike same cages. Mine came loose couple of times when first had bike. I snugged them up and no problem since. I will check bolts to see if steel or not. Glad he got it out no problem.

Wanderer

Just maybe, the bolt broke first!

GlennR

Here's the spec: 22 lb•in (2.5 Nm)

FBinNY 

That tallys.

Here's a chart that should be useful for those who need general torque guidelines.

Note the smaller diameters are generic hardware, and from 6mm up they go by class. High strength cap screws can take almost twice as much, see ratio for 10.9 vs 8.8, so there's a bit of upside room on a 5mm stainless WB bolt, but don't push your luck too hard.

On the bright side, if/when these bolts snap, the tension is relieved, so if they're not rusted, or Loctited in place, the remaining stud is very easy to remove.

Up North

Thanks! That is not much considering what we are asking those cages to do. Guess better keep checking more often and perhaps drop down one size in bottles. I have never lost a bottle yet so far.

chaadster

Oh, c'mon, and miss a chance to expound on ****** force?