ruirui

i have a carbon seatpost 31.6mm and plan to use it with my Blackburn EX1 Disc Pannier Rack.

pannier bag i'm planning on getting should hold about 1700cu or so... maybe bigger, but not sure at the moment. then a tent, sleeping bag, some simple cookware, food, tools, spare tires and tubes, clothes, etc.

would that put too much stress on the seatpost... or should i get a aluminum one just to be safe?

want to hear some veteran touring gurus's feedback.. thanks~

staehpj1

Not sure why it would stress the seat post. Do you plan to attach the rack to the seat post? I'd think you use braze ons if there, the brake bolt or p-clamps if not.

ruirui

my frame doesn't have any spot for brazed on. i got this seatpost clamp that allows the pannier to be connected onto it.

urbanescapee

That collar you acquired replaces the seatpost collar on your bike. It keeps the seatpost in place but the design primarily transfers any stress from the rack to the seatpost tube (the frame component) and not the seatpost itself. You should be fine so long as you don't over-tighten the screw for the seatpost; which would be a problem whether or not you had a rack attached. Or, if it still concerns you, you can attach the rack entirely to the frame; Tubus has the best p-clamp type setup that I have seen. They come in different sizes for differing tube diameters and are relatively cheap (~$9).

View the CLAMP-SET FOR SS MOUNTING FOR 21 MM at https://www.ortliebusa.com

Cyclebum

Interesting option. Didn't know it exist. Opens up possibilities for my very comfortable, light, Felt TT to be used for touring. Thanks.

You might find this article useful.

prathmann

I don't see an issue with that rack - as stated above it wouldn't be placing any significant stress on the seatpost. My concern would be with racks that attach only to the seatpost and are cantilevered back from it. A substantial load on that type of rack can greatly increase the total stress on a seatpost.

headloss 

Probably OK since the weight will be on the frame...

How are you attaching it to the post?

ruirui

urbanescapee: thanks for the link. i'll look into that.

Cyclebum: thanks for the link

prathmann: majority of the weight will be mounted from the rear skewer side.

headloss: using this seatpost clamp

likebike23

Are going to slide the clamp onto your seatpost or are you going to place the clamp over the top of the frame's seat tube? That clamp is meant to go over the bike's frame tube, not just to slide onto the seatpost. I am not a carbon fiber guy, but I know you need to be very careful about clamping things over carbon tubes or you could crush them.

staehpj1

Nothing wrong with the clamp if it fits your frame, If it doesn't and if it was my bike I would see if I could use the brake bridge bolt as the top anchor for the rack. I'd be more careful if the frame is carbon fiber, but would still use the rack.

paddybogman

That set up should be fine for getting your rack mounted properly, however you have to ensure that your heals don't strike your panniers. If heal strike is a problem the Axiom racks might be a better option.

fietsbob

You might consider a seat binder where the clamp and the frame slot dont all line up .. some have a mounting point to bolt on , onto the opposite side , from the clamp ..
like this one Universal Cycles -- Salsa Rack-Lock Seatpost Clamp

note the extent this seat post band goes to, to keep from lining up all the slots on this particular band clamp.

https://www.universalcycles.com/shopp...5&category=168 for a Carbon seat post in particular.


Of course you can always Buy a 31.6mm OD, to 27.2mm ID shim ..and use a metal,
aluminum, seat post, and resolve the crushed post may break if damaged over-tightening it, worry, ... entirely ..

That, Seat Post Sizing Shims, is what I have on 2 bikes .. 27.2mm seat-posts offer an abundance of choices .

I own Zero Carbon Fiber seat posts .. last one I Bought was Cane Creek Thudbuster ..

robow

I've used a similar set up at times while using an Axiom Trek Seat Collar with rack eyelets and had no problems though it might not be my first choice if you're considering 3rd world expedition touring.

btw, two thumbs up on the thread title.

seeker333

I think if something worries you to the point that you have to start a thread on it, then you probably should follow your gut instinct and not do it.

Proper racks and bags are sensible, and you'll never worry about them.

Philly Tandem

As others have stated, the seapost clamp with built-in rack mounts really has no bearing (pun intended) on your CF seatpost, as it integrates with the frame, not the seatpost. I put one of those on my wife's bike and it works just fine.

I also just installed those Ortlieb seatstay brackets on another bike this week, replacing some older "P-clamps" that I was using. I'm not convinced they are that much better than the p-clamps, and they aren't rubber coated to protect the frame, but they seem like they will do the job ok.

Do NOT use any sort of rack that clamps directly to a seatpost on a CF post. A friend of mine was determined to use one on his Pinarello (!!) despite my warnings, and it broke his seatpost in short order (an expensive lesson for him).

ruirui

thank you all.. i think i will get an alum seatpost just to be safe...

staehpj1

No harm if it gives you peace of mind, but I wouldn't bother. The extra expense and weight increase (even though pretty minimal) of another seat post get you no real benefit IMO.

ruirui

thanks to everyone's reply. i think i will get an alloy seatpost instead an keep my carbon one for other days..

likebike23

You never really answered whether or not you were going to use the clamp as designed (on the frame) or clamped over the seatpost (not on the frame). If you are using the clamp on the bike's frame as it is designed, then you won't need a new post. If you are clamping it directly on the post, an aluminum post would probably be better, but not ideal.

ruirui

sorry about that. i'll be using it on the seatpost instead of on the frame itself. my friend has a seatpost collar that will fit 31.6mm diameter that is used for pannier rack. don't have it with me at the moment, but can post up photos later.

i can't use it on the frame because my CX has canti brake, so the original seat collar needs to stay as the brake cable is routed through there.