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In preparation for this years bike packing jaunt I finally pulled the trigger on some fork bags in an attempt to avoid taking any sort of bumbag or backpack and have everything hanging off the bike instead of me
I bought a couple of these
https://www.topeak.com/global/en/product/1129-VERSACAGE
with the view that I can use the bosses on my Ragley Trig forks for mounting, in my head, I know the carbon is probably fine and more than strong enough but as a bike material…it just makes me nervous which leads to questioning EVERYTHING
The cage itself states a maximum load of 3kg and with the stuff I’m planning to put on them I reckon at the very most, 2kg either side
so cage weights aside, what about fork weights on the bosses of carbon forks? Surely they’d take enough of a beating with movement and lumps and bumps and all that to warrant some kind of limit? Assuming limits in place, are these hard and fast rules or more guidelines?!
how tight do you tighten the bolts to ensure a secure fit without risking damage to the fork?
I realise I am more than likely overthinking the whole thing so keen to hear everyone’s thoughts / experiences of using the bosses for cages and bags on their carbon forks
Any bike fork tested has to meet the pretty rigorous CEN test - the additional weight of 2x3kg bags is pretty insignificant in comparison to the 100kg of rider they'll have been designed to accommodate.
The mounting bosses are solid metal inserts - with over-tightening there's more risk of stripping the threads than damaging the fork - so the general guide for 5mm screws onboard bikes in no more that 5-8Nm of torque.
I fitted a three bolt cargo cage to my alpkit pathfinder mtb fork and the sounds it made when flexing the cage have made it a solid nope for me. My feeling is that it might be OK in normal use but the slightest crash or bump into something solid would rip the side out of the fork.
Carbon is strong and the extra force compared to say me riding the bike and weighing 100kg are small
Personally my paranoia would be reserved for the risk of anything rubbing on the carbon. Carbon will really not tolerate that. Another concern is anything falling off the mount. A mate had a bag wiggle free, it was dragged through the fork ripping out a brake hose
I'll counter the above with having run my Travers prong carbon fork with cage mounts for a good few years of use with zero problems.
The new gravel bike also has carbon forks with cage mounts. Only two trips so far but all good so far. Well I'm not dead yet.. apparently
I think the general rule is 1.5kg per mounting point. So a 3 bolt fork should be ok up to 4.5kg
I only ever put light loads in my fork packs as I don't like the feel of weight there. Certainly under 2kg
I have had those on my gravel bike fork, but I only used it for high-volume, lightweight stuff. Bivi bag, mat, or lightweight cooking gear. Never put more than a kilo on each. The other thing I did was ensure the strap went around the back of the fork so the strap was taking some of the load rather than the mount.