Ridley Kanzo Fast Seat Post Issue

I tried to avoid posting this thread but I have given Ridley plenty of time to make things correct/respond and the lack of response and having to resolve the issue myself made me want to assist any other user that may run into this.

This is not a thread to be-little or discourage anyone from buying a Ridley Kanzo Fast, in fact this is the most impressive bike I have ever ridden and that says a lot as I have ridden so many different material and bike manufactures over the years.

The Kanzo fast is the stiffest bike I have every owned (it does have a BB infinit single sleeve BB) and it is freakishly fast on the flats/straights. I was able to get the bike down to 16.5lbs in race trim but upped it to 17.1lbs by adding some more reliable tires with better width. I also changed the crank from a Sram Red to Dura-Ace as it is my preferred crankset - what I am saying is the machine is stiff, light and aero.

The issue!

When I first purchased the bike (from competitive, which is amazing) I immediately had issues with the seatpost slipping in the frame. I attempted everything from paste, caulk, roughing the surface and ultimately shimmed the seatpost with soda can slivers.

I eventually was able to have the complete bike sent to competitive cyclist and ultimately the frame and seatpost was warrantied from Ridley. The frame and seatpost was out of spec and not able to fully cinch and that was the cause of the dropping.

We then fast forward to January of 2022 when I get my bike back from warranty.

Before we continue any further here, I want to say that this issue is only affecting 7x9 carbon railed saddles!!!

The very first ride on the trainer the saddle rolls back while ridding (I ride a s-works Phenom, this particular saddle is brand new from dealer). I think its weird and retorque it and test again - I ultimately find that I can by hand cause the saddle to roll in either direction, after closer inspection I decided to contact Ritchey (who is awesome also) as they manufacture the clamps for these bikes and explain to them the situation.

They send me another head unit to test and it does the same exact thing. I provide Ritchey with detailed photos and measurements of various points that they request. They analyze the information for about 2 weeks and email me back with a nice long apologetic email explaining that the seat post for the bike has been manufactured in a way that not all seat post rails are compatible (although Ridley calls out for them to be).

The seat post diameter where the ears clamp is 2mm to wide and causes the system to bottom out (which I had already discovered). They recommend that I reach out to Ridley and let them know and see if anything can be done.

I have tried for 2 months trying to work with Ridley on this matter and to just be honest there is no communication between us. They eventual answer me and tell me they have never seen the issue before and ask that I contact the USA main distributor (and provide me with their information) and this is where I sit as of now.

Now - A little about me.

I don’t wait around and I don’t typically take no as an answer. I have a background in automotive, and machining. That being said, as my wife best describes I am an idiot haha.

I went to work right away when I started having the issue with the clamp and started machining the clamps. I ultimately took 0.047 of an inch off each ear (or 1.2mm) and this fixed the bottoming out aspect. I was then having more success with it not rotating unless I hit a large hole/crack/vibration in the road. I ultimately threw torque values away and just tightened the clamp tight without going crazy - this solved all of my problems and the bike is now solid.

Will it last? Well if the carbon head fails from over tightening, then no - besides that yes haha.

This issue again is for 7x9 rails, traditional round and 7x10 rails may not have this issue. If you are like me and are not willing to change saddles and it uses a 7x9 rail please be aware you may have some issues.

I hope some of these photos help and my post helps people in the future, maybe its just my setup, maybe not.

Thanks for the great post.

I bought my KF ( kanzo fast) from C/C a few months ago and I love it. I’ve been a rodie since 1971. Joined the ABLofA ( amature bicycle of america) in the eight grade. ( yeah, i still own the shoes with an aluminum slotted block on bottom for the cheese grater pedals with toe clips and a helmet with leather tubes stuffed with foam :slight_smile: But got tired of the knuckleheads’ buzzing me on the road so now I ride gravel almost exclusively.

Anyway, I have a saddle I want to use but it has oval carbon rails. ( The S-works Power Mirror)
The current clamp won’t accommodate that of course so I’ve been trying to find the right clamp. But after reading your wonderful post, I’m not sure I should try.

Any suggestions w/b greatly appreciated.
Mitch Williams


You are very welcome!

I am very sadden to say that my Kanzo fast has been warrantied and returned at this point and displaced with a Aspero. I wont go into comparisons between the bike because its not necessary in this situation.

HOWEVER - you may be in luck as I may still have my machined clamp and ears from the bike. Please send me a DM and I will look when I get home.

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Excuse my ignorance, but how do I do a direct message? :confused:

Click the icon next to the user’s name and click the red Message button