Minimum insertion on a syncros hardcore seatpost

[Edav97]

Hi all,

Does anyone know why the minimum insertion depth is on a syncros hardcore seatpost? I’ve got one that’s been cut and I need to know how much I should have below the frame.

Cheers

 

[Tootyred]

As I always say...."if you havent got 4" to spare, don't bother sticking it in"

 

[Edav97]

As I always say...."if you havent got 4" to spare, don't bother sticking it in"

Words to live by! It’s likely going to be bang on 4” tbh so I may just about get away with it.

 

[bikeworkshop]

It's usually the frame that fails with inadequate insertion, not the post.

Good frame quality, esp. aluminium, extended seatpost collar, lightweight fillet, poorly shaped slot all demand a better/ longer fit.

A higher saddle breaks the frame quicker too.

 

[Edav97]

It's usually the frame that fails with inadequate insertion, not the post.

Good frame quality, esp. aluminium, extended seatpost collar, lightweight fillet, poorly shaped slot all demand a better/ longer fit.

A higher saddle breaks the frame quicker too.

I’m actually putting it on a steel frame road bike, so maybe this isn’t the best place to ask, but I know syncros are more popular in the mtb world.

The seat tube is 26.8mm and has been cut to 200mm below the seat post clamp. It’s a steel frame in Columbus Cromor tubing. The frame is 51cm and I tend to ride with 100-130mm of post out of the frame. This leaves me with 70-100mm of post within the frame. So at the most a fifth of the overall seat tube length.

How does this affect your thoughts on it?

 

[bikeworkshop]

Lugged Road frames have a lot of strength at the lug.
Vintage franes often only had 3 inches of post insertion, with 4" projecting, so the frame builders would be expecting this.

So if its a lugged frame and the post is a nice fit, and the slot looks tidy, it's fine.

If its fillet brazed, with a sloping toptube, the builder might be expecting 120 min insertion.

The post isn't the problem if it's the right size - it's the seat cluster.

 

[Edav97]

Lugged Road frames have a lot of strength at the lug.
Vintage franes often only had 3 inches of post insertion, with 4" projecting, so the frame builders would be expecting this.

So if its a lugged frame and the post is a nice fit, and the slot looks tidy, it's fine.

If its fillet brazed, with a sloping toptube, the builder might be expecting 120 min insertion.

The post isn't the problem if it's the right size - it's the seat cluster.

Yep, lugged frame. Sure, I’ve seen the old campganolo posts that are barely 180mm total!

Thanks for your advice