I received this email from Canyon which I would think its going to address the creaking problem and also address possible water/particulate ingress.
TLRD version: Insert this cap which should act as a buffer to resolve creaking and water from going down the seat tube.
Thank you for your recent purchase of the latest-generation Aeroad bike. We hope the bike has inspired you to ride and that you’re enjoying it on the road or during your winter indoor training sessions.
The Aeroad as you know, pushes the limits of road bicycle technology with it’s aerodynamics, lightweight, cockpit adjustability and torsional stiffness for ride responsiveness while maintaining vertical compliance for comfort. One very important feature we want to point out is how the Aeroad seatpost allows for a higher level of flex to increase comfort while maintaining pedal power transfer efficiency for demanding rides thanks to its newly developed clamp design.
However, when the bike is ridden in excessively wet conditions, water can carry dirt down the seatpost into the seat-tube which may lead to increased abrasion between the seatpost and the seat tube, but that abrasion/wear is not a safety concern. You can rely on our German engineering to be the highest quality for your Canyon bike.
To protect your seatpost and prevent any dirt from entering the seat-tube, we will send you a seal with installation instructions, free of charge. Producing the seals may take a few weeks and at the beginning of March, we’ll let you know when to expect a shipment. You do not need to call us or reply in any manner.
Until then, we would like to give you some important advice on looking after your Aeroad: remember to regularly clean and maintain your bike, especially after riding in rainy and muddy weather.
You should make sure to clean the seatpost and the appropriate area in the seat tube after a rainy ride or after washing the bike. Please only use grease when mounting the seatpost, as assembly paste can increase wear (see also the Quick Start Guide).
We’re keeping our fingers crossed for Spring to come early, so that you can soon enjoy miles and miles on your new Aeroad. We hope that this service information was helpful for you. If you have any questions, our service team will be happy to help.
Best regards,
The Canyon Team