Zipp Service Course SL 400mm Seatpost

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Product Description

Fit And Performance
Since the introduction of our line of Service Course SL components we’ve had amazing success with our pro level athletes in all disciplines. While the successes have been proving, we have also drawn from their feedback. We not only learned how and why athletes make their equipment choices, but how our manufacturing methods and materials affect product performance. With new knowledge as well as new engineering, we are proud to introduce our completely redesigned Service Course SL seatpost with a carbon tube and aluminium head for better shock absorption and weight savings.

Things To Remember

  • New lightweight clamping system
  • Changing the tube material to carbon, and adding length and sizes


  • Material (SP/ST):  Unidirectional Carbon/AL-7075 head
  • Post diameter:  25.4mm, 27.2mm, 31.6mm
  • Post length:  400mm
  • Colour (SP):  Matte with stealth decals, Matte with white decals
  • Hardware:  Steel
  • Clamp Material:  Al-7075
  • Offset/Setback:  0mm, 20mm


Occasionally, without notice, manufacturers change product design and/or specifications.

Seatposts Guide


Seatpost Guide

A seatpost is the part that connects your saddle to your bicycle frame. The seatpost is designed to fit perfectly inside the seat tube of the bike, there are various sizes available, the size must match the seat tube exactly. The top of the seatpost has an included part known as the saddle clamp that clamps around the rails of the saddle and allows forward and back adjustment of the saddle along with saddle angle adjustment.

You might see there are various sizes of seatpost available, for example, 27.2 x 400.
This refers to the diameter of the seatpost and the overall length. The diameter must be exactly as intended for your bike, if you are unsure what size you need, it should be stamped or written on the old post. If the size is not shown, the manufacturer's specifications should show what size is needed.
The length is often more than needed, but check the total length of your existing seatpost to check what length is needed. Some riders with small frames might need to cut the post shorter to lower the seat to the correct height.

Please note the minimum insertion mark that shows the minimum amount of post that must remain inside the bike for safety reasons.

Rigid Seatposts

A rigid seatpost is the tube that slides up and down inside the seat tube of the frame allowing you to adjust the height of the saddle for different leg lengths. A rigid post is the lightest type of seat post and is seen on the majority of bikes. There are various sizes available to suit different frames and can be made from aluminium, titanium or carbon fibre.

Seatposts can be available in different lengths to suit riders who need a lot or not so much extending out of the frame. The top section near the saddle clamp can also have a setback, where the saddle clamp is offset to the back of the bike or they can be straight to suit the different fit and reach preferences.


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Rigid seatpost

Dropper Seatposts

Dropper seat posts let you adjust the height of the saddle easily while riding. A relatively new addition from the world of mountain biking, the dropper seatpost is now seen as an essential addition to any mountain bike. Having the saddle at the correct height for pedalling efficiency is great until the terrain changes and you need to drop the saddle out of the way so you can move your body weight around without the saddle being in the way.

A cable or hydraulic hose feeds from the post up to a remote actuator on the handlebars. Some frames support internal routing for this cable/hose, known as internal or stealth routing. Other frames only support external routing, there are also externally routed dropper posts for these frames. The standard seatpost diameters apply, along with the different lengths. Dropper posts are also available in different amounts of drop to cater for different leg lengths.


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Dropper seatpost

Suspension Seatposts

Suspension seatposts can look like dropper posts but instead of dropping out of the way with the press of a lever, they remain at maximum extension until you ride over a bump. A suspension seatpost with have a certain amount of travel to tame a bumpy road and make cycling more comfortable. They are sprung by air, coil or with an elastomer.

The same variables apply to suspension posts as to other types. They are available in different diameters to suit different frames, and different lengths to suit different leg length.


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Suspension seatpost

Seat Clamps

The seat clamp is the part that secures the seatpost in the frame to stop it from moving. They are made in different sizes to suit different frames. The size of seat clamp is not the same as the size of the seatpost. The seat clamp will always be a larger diameter than the seatpost to cater for the thickness of the frame.

There are quick-release seat clamps that give tool-free adjustment. Standard bolted seat clamps and even ones that include mounts for a rear rack or a guide for an externally routed dropper seatpost.


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Seat clamp


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Delivery & Guarantee

UK Delivery Information

International Deliveries – Temporarily Suspended 11/11/20

Note: We are still offering deliveries to the Isle of Man, Scottish Highlands, Scottish Islands, Channel Islands, Isle of Wight, Jersey and Guernsey. 

Courier Delivery update: Due to the COVID19 situation, we are currently experiencing some delays with deliveries. Our couriers are working around the clock to get your order to you as soon as possible but there is a potential delay of up to 48 hours . Please check your tracking on track your order here.

Please download the TNT Track and Trace App for iOS here and Android here so you can keep an eye on your delivery and any further updates.

Please note on the TNT tracking app it may show your delivery status as ‘Collecting’ (as per image below). This means your delivery has left our warehouse and is currently held at TNT main depot and there could be up to a 48 hour delay.

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Please keep checking the TNT tracking for further updates. On behalf of TNT we apologise for any delay and inconvenience this may cause. 

We are committed to offering fast and free delivery, whether you're ordering bikes, accessories or clothing. Our standard delivery service is FREE in the UK, regardless of the size and on all orders over £20.

Please note that bulky products and bikes shipped to outlying UK regions are excluded from free shipping.

Please note that Pre-Order dates can sometimes change due to updated stock information.

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We will give you a full refund on any item that is returned to us unused/unfitted, in a resaleable condition and in its original packaging (where possible).

Please note: For hygiene reasons, we cannot accept returns of facemasks, undershorts or underwear if the item has been removed/unsealed from its original packaging.

If your item develops a fault or arrives damaged, please contact us first so we can resolve the issue for you as quickly as possible.

For more information please visit our Returns & Warranty page.

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