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Carbon Frame Work
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
Does anyone know a place (or even if its possible) where I can have some bottle cage mounts fitted in an existing carbon frame?
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Why wouldn't you just try something DIY? If the frame is round I reckon you could get enough tension using cable ties to hold a cage on. Especially if you put some self adhesive foam on first to stop slipping. Use two small ties for each bottle hole (you might have to double/triple up to get round the frame) to even out the seating.
Failing that, drill a hole and glue 4mm nut into the frame with strong epoxy. Use a bolt with stand off to hold the nut in place while drying (think plastic pizza 'table' that comes in the centre of your... erm... pizza). How hard can it be?
Stan at Bike Addiction does carbon repairs so he could probably do this for you.
Thanks. I'll call BA tomorrow
You've got it all wrong Rob.
(Do I need to say "don't try this at home or with a frame you want to ride in the future"?)
Just drill a hole through both walls of the downtube and chuck a 1/4" coach bolt through.
+1 for Stan. I wouldn't try DIYing a Rivnut or Nutsert as the tube could (should) be extremely thin in the middle of a down tube. Local reinforcement is likely used when mounts are incorporated in a frame design.
Or if you insist on sophistication to match the quality of your frame, you're best going to someone who repairs carbon frames. Though don't hesitate to look around and ask for prices if that scene, where you're located, is anything like here in Perth...
Err, drilling holes into a carbon frame would surely end in tears.
I don't think there's too much to fear from drilling rivnut holes in your downtube.
In relation to alloy bikes, they don't have any extra material around the holes, it's too hard to engineer, yet despite being so thin I don't think I've heard of any frame failures that have started from the rivnut holes.
With carbon, the biggest issue is taking care when drilling to avoid any delamination of the layers on the interior of the tube. A nice sharp drill bit, Ti-nitride coated, light pressure and high speed would be my guess, although I'd want to test it on a piece of discard material first. And then I'd be looking to seal the edges of the hole with water resistant superglue.
Some carbon fibre resins are so hard that the drill bits are only good for a half-dozen holes before they have to be chucked, and the holes need to be started with a fine dremel tip to avoid the bit wandering. At least that was my experience when fabricating CF parts for model R/C race cars.
It's doable, but probably not a DIY job if you love yor bike.
Yes, yes, but if you are at all cautious then don't ever considering putting holes in the frame. I thought it was a given this would be an old frame and he didn't care if it buckled on the first ride
No this is my Agogo. Definitely don't want to trash it
For what my 2 cents is worth and my limited experience with carbon fibre, avoid drilling any holes in it unless it is absolutely necessary.
If you really want the bottle holder I would suggest just epoxying a couple of M5 nuts to the frame and make sure the bolts aren't to long and hit the frame and possible rip your nuts off.
How do you think the manufacturers fit drink bottle rivnuts, cable guide rivnuts, and so on?
My weight-weenie Scalpel 29r has holes all over the downtube, and the current year model has a whopper of a hole down low in the seat tube for a ... dropper post remote cable
Providing the drilling is done with care and attention, and you're only looking at say another two or so, I see it as no more risky than doing the same in an alloy frame.
Stan at BA is reputed to know his stuff re: composites, so I'd be taking his advice. If he says no, then fair enough. If he says yes it can be done with little risk, then I'd accept that too.
They design the frame knowing where the holes are going to be
If you're suggesting they put extra material around there, I'm reckon most of the time they don't bother, unless it's a load-bearing point.
But that's a guess, I'll admit. Encouraged by the fact that most rivnut bolts are limited to a ~3Nm fastening torque.
I'd suggest that before investing tens of thousands in CF molds and countless $ in risk and warranty that most high zoot frame designers would do a fair old stress analysis and detailed design. Especially when talking about frame weights in the sub 900g range.
I suspect that the agogogogogo doesn't have frame holes in the DT because the low cost manufacture didn't allow a margin to a) do the required calcs, and b) add the mold/layup complexity to the process, and c) achieve the fantastically low weight for price that they managed.
Bri, see what Stan says, but if you can flex the tube section by squeezing with your finger tips I'd suggest that the stress of chucking a bottle in, or wrenching one out, in the heat of the moment is highly likely to rip any insert out of the frame. Best option could be to mold a cage that wraps the DT and is retained with a couple of cable ties or band clamps. It won't be pretty or light but will be reversible and probably pretty safe.
The down tube has bottle cage bolts but I want to move the cage up the tube so the current upper bolt becomes the lower one and then add a new upper one.
I then want to add a cage to the seat tube as it currently doesn't have one there.
I think Spesh has some seat post clamps that allow you to fit a regular bottle cage at the back without it sticking out too far and snagging the family jewels.
That's an option if fitting one to the seat tube doesn't work out.
if slowpup's comment about the compressibility of your downtube is accurate please disregard all my earlier comments. If a CF down tube did that I'd be concerned even with no holes in it at all.
Brian I have the perfect solution for you. It won't ever damage your frame, it will no impact on your bike weight, they are very common with mountain bikers and best of all they are available from one of "our affiliates"
http://www.torpedo7.com.au/shop/bike/hydration-p...
Ok, all jokes aside, get yourself a small strip of aluminium about 150mm long by 20mm wide by about 3mm thick. Drill a hole in the middle of it big enough for the cage bolt to pass through. Drill another hole the same size 65mm (I think) centre to centre away from this centre hole. Drill another one at the other end. Fix the bottom hole of this "bracket" to the lower of your two frame mounts, fix the lowest cage mount through the middle hole of the bracket to the upper frame mount. Get yourself a small cup head bolt just long enough to fix the top hole of the bracket to the top hole of the cage. You'll obviously need a nut as well and a spring washer wouldn't go astray. There, you have just moved the cage up 65mm to give you room for the seat tube cage without changing your frame cheaper and lighter than adding a new fixing hole.
For the seat tube cage I would be getting 2 band clamps, some double sided outdoor quality adhesive tape (available at bunnings). Run the tape down the seat tube where you want to mount the cage and also around the tube in line with where the cage fixing bolt holes are. Clamp the cage to the seat tube with the band clamps sitting on top of the tape. The tape will stop the clamps from slipping, also allow a little bit of give so that the clamps and cage "bite" in without you having to apply so much force as might otherwise squash your tube. It ain't pretty but it will work and will probably only add about 50gms to bike weight over what your bolt on cage would have added. Just check it regularly after / during your first few training rides to make sure it isn't moving.
Good luck.
Some interesting ideas here, good to see people thinking outside the square!
I've done this before, with some level of success. Carbon bikes are made by bonding a number of layers using epoxy. You can follow the same process to stick your cage on.
I simply glued a carbon cage to a carbon frame with epoxy. It's not as strong as the bond between the frame layers, but you don't need that much strength anyway. Its also a good thing if you want to remove the cage, in which case there are 2 options - similar to removing a band-aid from hairy legs fast or slow. Fast requires you to snap the DIY epoxy, which you might not want to do. Slow is gently cut/sand away your mod.
I've used the 5 min set epoxy from bunnings. This is not as strong as slow curing epoxy, but probably worth a try first off. It broke when someone tried to lift the bike using the cage as the single lifting point...
RE trying to drill a hole. Consider where you want the hole as it may be difficult to get a drill inside the main triangle. Delamination is very likely too, resin ratios can be pretty low.
They are definately reinforced and a little thicker on the outside of the frame.
Proceed with caution mate!