Hi all, I'm getting close to comfortably fitting my new classic. But the seatpost is worrisome, so I've only rode it at home on my rollers. Currently it is inserted about 1.75 inches. I'm 160 lbs, 5'10". The seatpost diameter is 26.4mm, so not the easiest to find. Last week I bought a 300mm long Suntour XC on eBay, but it is 26.6mm. Is the ream/hone job fairly routine for a good bike shop? These crazy times, IDK if my favorite mechanic is even available. (The stem height is safe, a good ways inside of the minimum.)

With that much post exposed, perhaps the frame is just too small. And no, not nearly enough seatpost left in the frame to make me the least bit comfortable.

+ 1. This is a cool bike but maybe that frame is too small.

Kalloy makes a 350 mm 26.4 seat post. That will give you a safe amount of insertion.

I see what you both mean. The stem is only 100mm long, so the reach is fine. And the bike feels great. I could comfortably lower the stem, but the seatpost would have to stay up. Thanks for the perspectives.

Can you get a local machine shop to turn the seatpost down by .2 mm as far as the minimum insertion range? I’d rather weaken the post than the bike!

That sounds pretty f-in' smart. Seems like I'm always in search of a small, friendly machine shop.

The proposed 26.6mm replacement seatpost looks rather nicely anodized.
OTOH, the two best mechanics in my area are well into their 70's.
I suppose, being a relative youngster (kidding) at 58, I should keep my distance for a while? What a f_cked up situation this virus has us in.



Thank god for the n+1 advice from you all, I have another bike to ride. Whew!

Most of us have sanded down the .2 by hand at one time or another, you can even use an internal pipe wrench to hold it on a drill for power assist albeit a little tricky.

And no, that is not enough insertion.

I strongly agree, frame is too small. I face a similar situation with my Colnago. I wish it were 1 cm bigger. I have to use a Brooks Pro on it to get the post down in the tube far enough.

Velo Orange also makes this 300mm long post in various sizes. I'm using it in 26.4 on my Motobecane and it's perfectly fine for the intended task.

https://velo-orange.com/collections/...-one-bolt-post

I would use the bottom of the cast in height measuring "ruler" on the seatpost as the minimum insertion mark. It looks like you are well below it, so only solution will be is to buy a longer seatpost ti get more insertion legnth. Your height would typically ride at least, a 58 cm sized frame. That Gitane looks to be a 54 cm?
BTW, welcome to the 84 Gitane TDF club!
Here's mine.....

I rebuilt it up to my personal preferred "Tout French" specs.

SJX426: That's a tough pill to swallow! I'll probably try the longer seatpost first. It's an amazingly smooth, nice handling bike. Probably the best I've ever ridden. So I take it you still have the Colnago, despite it being too small?

Chombi1: Yes, it's 54cm ctc seat tube, and 55cm ctc top tube. Proper frame sizing is difficult to figure out! I've tried websites, bike shop fitters, etc. For now, it seems like I prefer the smaller bikes. Maybe I need another bike??? OMG, I must be ill.

cyclic_eric Yup
1983 Colnago Superissimo, on Flickr

Very Nice Bicycle! Yes, impossible to kick out of the garage, or living room, or den, or ...
(I was looking for the cool dude emoji with sunglasses, but the available list is very small. Another internet mystery.)

If you search for "minimum seatpost insertion" on BF, you get a couple rules of thumb. (I know because I decided to chop down a seatpost, and geeked out about it first. )

At very minimum, it needs to extend below the bottom of the top tube, to make sure it's not cantilevering into a void. You've got that.

Beyond that, it's recommended to have at least two (or two and a half) diameters of extension in the seat tube, to spread out the contact and avoid cracking the seat tube. That would be 53-66mm. You're falling short there, unfortunately.

The good news is that there are inexpensive long 26.4mm seatposts out there. I agree with others that you could probably do with a frame that's a size bigger, though.

ThermionicScott: Thanks for the geeked-out information!
The current seatpost is roughly 9" or 225mm long, measuring from the saddle rails to the end. Luckily, the Suntour post is ~11.75" or 300mm long.

The 56cm bikes have always felt a little more sluggish than the 54cm bikes, in my limited experience.

I think that with a taller saddle, this seatpost would be just long enough!

It's often the case that us long-legged types struggle to find the perfect stack and reach in a vintage racing frame.

At least with this bike I don't see this rider running the saddle back on the rails, so the post's durability won't likely be tested as when a saddle gets slid rearward.

My Gitane TDF reminds me of how I struggled to find the needed height, it's still my smallest bike so still looking for a new home.
The saddle is slid back because the seattube angle on this small frame is quite steep, though the reach is still short for me.

Nice and shiny!
The stem doesn't look too long, yet..

Answer. Much less expense/trouble than turning down an otherwise perfectly good seat post.

That bike is beautiful. I have a 59 cm Gitane TdF (same color) that I haven't decided what to do with yet.

Is this a 54?