Lightweight pannier on a carbon frame?

[Norv]

Evening all,

I currently use a small seat-post mounted pannier rack to carry a little bag, with a change of clothes in, for commuting. This is a on an road race bike, with an alu frame (carbon forks and stays).
I also have a full carbon frame racer for weekend rides. In June, i'm gonna be doing the Exmouth Exodus, 100 mile Audax. I want to carry that same, lightweight pannier on the carbon frame bike, so I can carry a water-proof, clean jeans and a t shirt, aswell as puncture accessories. I can carry all this with no problem at all on the alu framed bike, but i'm not sure if this is a good idea with the carbon frame. Should I just leave the rack at home and take a rucksack? Or will it be ok?

Thanks!


EDIT: The bike has an alu seat-post.

 

[bianchi1]

What sort of rack is it? Cant answer your question im afraid but am looking into getting a rack for a lightweight tour in the summer.

 

[Norv]

This rack: http://www.topeak.com/products/Racks/MTXBeamRackEX

With this bag: http://www.topeak.com/products/Bags/RXTrunkBagDXP

 

[bianchi1]

nice one. just the things i was looking at! My seat post is carbon so i will be interested in the answer you get.

 

[RedBike]

I think you should be wary about using devices like this on light-weight racing frames in general. However, I really can't think of any specific about carbon that would cause a problem.

 

[Norv]

Yeah I see. I just don't want the tubing to randomly snap or have its life span drastically shortened. Bare in mind that the extra weight is minimal. The rack and bag add up to 3-4 pounds. Plus say one more pound for a t shirt and some shorts.

 

[Dave5N]

I expect you are a fair bit heavier than your spare shirts.

Rucksacks are terrible for cycling. All the weight's on you, and it's hot to boot.

 

[walker]

can I pose the question 'why'?

 

[Stick on a Giant]

I've seen recommendations that that rack is only used with an alloy seatpost, not a carbon one due to the pressure of the clamp. I would think the frame would be fine though, as the seat tube is already coping with your bodyweight, so a couple of extra pounds is neither here nor there.

 

[Norv]

Thanks Stick on a Giant, that's some handy re-assurance.

Walker, reason being that at the end of the ride, i'll want some warm comfy clothes for travelling home in. If the ride was a circular route, starting and finishing at home, I wouldn't bother.

 

[Alves]

All the seat post clamping racks and saddle bag devices, I've seen specifically say "Do not clamp onto carbon posts" in the small print. I don't think it's the extra weight so much as the secure clamping and added forces (& the vectors produced by a small weight at the end of a rack) is not what a carbon post is designed for and is outwith the design parameters.
I definitely would advise against using a rucksack, horribly and sweaty. Carry a dry undershirt/vest in your back pocket and put that on underneath your sweaty shirt when you stop.

 

[walker]

Thanks Stick on a Giant, that's some handy re-assurance.

Walker, reason being that at the end of the ride, i'll want some warm comfy clothes for travelling home in. If the ride was a circular route, starting and finishing at home, I wouldn't bother.

Can no one pick you up?