Author Topic: <Thread now pretty OT> How much does size matter? Seat post help.  (Read 2204 times)

Teh Commuter is a bit of a Trigger's Broom. The seat clamp has finally given up the ghost and I need a new one (seat post, not bike).

No markings on the seat post whatsoever. I have no clue as to how old it is. The frame (531) was built for band-on downtube levers (no braze-ons on the down tube) which to my mind puts it before the 1980's*. I wouldn't be surprised if the seatpost was the original...

Anyway, a 27.2mm seatpost fits, and fits relatively easily, with some force required but no swearing. But it is noticeably tighter in the frame than the old one.

IF the frame is built for 27.0mm, will I cause damage and disaster by running it with a 27.2mm post? I don't fancy ending up on my arse in the middle of the road...

Ta awfully!






*Is this assumption correct?

LittleWheelsandBig

  • Whimsy Rider
Re: How much does size matter? Seat post help.
« Reply #1 on: 29 December, 2013, 04:54:39 pm »
Run the largest diameter that fits at the depth you need. It won't hurt the bike/ get jammed unless the seat tube has been over-reamed.
Wheel meet again, don't know where, don't know when...

Chris N

Re: How much does size matter? Seat post help.
« Reply #2 on: 29 December, 2013, 05:18:18 pm »
Yep.  If it slides in without a hammer, you're good.

Oh, and buy a cheap set of digital calipers (or even some vernier ones if you like).  Invaluable for measuring all sorts of stuff.

Re: How much does size matter? Seat post help.
« Reply #3 on: 29 December, 2013, 06:05:55 pm »
IF the frame is built for 27.0mm, will I cause damage and disaster by running it with a 27.2mm post? I don't fancy ending up on my arse in the middle of the road...

If it works, it works! Steel frames never tend to break suddenly into parts like other materials do.

*Is this assumption correct?

My guess is: before 1990. My 1986 10speed bike had no such braze-ons, but I have to admit it was a rather cheap one.

Re: How much does size matter? Seat post help.
« Reply #4 on: 29 December, 2013, 07:13:05 pm »
Seatposts do vary slightly. When I was swapping bits about the bikes a few years ago (I'd bought a new frame) I found that, out of a black & a silver seatpost, both new 27.2 dia stems, one was too loose in the frame I wanted to fit it to and the other was too loose. I swapped them and they fitted fine.
If it ain't broke, fix it 'til it is...

Re: How much does size matter? Seat post help.
« Reply #5 on: 29 December, 2013, 09:41:52 pm »
Thanks all. The new post is substantially longer than the old one, and fits fine all the way down. I'll run it like this.


Follow-up question: do quill stems ever fatigue? I cleaned the bottom end of the stem up and it looks OK. For the first time I could see that the brand is "Sakae Taiwan". A quick trawl of Teh Interwebs reveals a picture of a stem much like mine and the information that it was manufactured in 1988....

LittleWheelsandBig

  • Whimsy Rider
Re: How much does size matter? Seat post help.
« Reply #6 on: 30 December, 2013, 07:58:25 am »
Only a couple of fairly obscure stems were known for breaking. Sakae and Sakae Ringyo aren't in that small group. I'd happily keep using it.
Wheel meet again, don't know where, don't know when...

Re: How much does size matter? Seat post help.
« Reply #7 on: 30 December, 2013, 08:47:27 am »
Only a couple of fairly obscure stems were known for breaking. Sakae and Sakae Ringyo aren't in that small group. I'd happily keep using it.

Cool. Thanks.


OK: Follow-up follow-up question: Assuming the stem is the original, I've dated my bike now, to around 1988, which is a bonus! It was built around the time of my first, ahem, proper relationship. Which is apt, somehow.

But unlike the girl in question* I have no way of finding out more about the frame, I don't think. It was badged as Ellis-Briggs when I bought it but E-B say it's not one of theirs. Four digits stamped under the bottom bracket is the only ID marks I can find. From memory, 94xx.

Anyone got any ideas as to how to go about identifying the frame? She'll be due a respray at some point and it would be nice to put the original decals back on if that's feasible. I've a new commuting machine and this one may be promoted to "lugged pretty bling for Sunday pootles 'n posing" in honour of the work it's done over the years.




*Marlene, since you don't ask. Brunette. Big brown eyes. <Sigh.>

Re: How much does size matter? Seat post help.
« Reply #8 on: 30 December, 2013, 10:05:16 am »
Quote
Thanks all. The new post is substantially longer than the old one, and fits fine all the way down. I'll run it like this

A word of advice, make sure the pin and inside the seat tube are well greased before insertion  :o I have spent a significant amount of time in the last 30 odd years removing seized seat pins. Long ones are the worst as the corrosion has a larger surface area to work on. You only need about 4 to 5 times the diameter of the pin in the frame unless it is a compact style frame with yards of pin siticking up. Use a decent synthetic grease, not the white stuff which seems to exacerbate the corrosion problem.

Cheers

Dave Yates
It's not just hitting it with a hammer but knowing where to hit it and how hard

Re: How much does size matter? Seat post help.
« Reply #9 on: 30 December, 2013, 01:30:26 pm »
Quote
Thanks all. The new post is substantially longer than the old one, and fits fine all the way down. I'll run it like this

A word of advice, make sure the pin and inside the seat tube are well greased before insertion  :o I have spent a significant amount of time in the last 30 odd years removing seized seat pins. Long ones are the worst as the corrosion has a larger surface area to work on. You only need about 4 to 5 times the diameter of the pin in the frame unless it is a compact style frame with yards of pin siticking up. Use a decent synthetic grease, not the white stuff which seems to exacerbate the corrosion problem.

Cheers

Dave Yates

Thanks Dave. Off to the LBS for a new tub of grease I go!


(Now that you're here: You didn't by any chance build frames with 4 or 5-digit numbers stamped underneath the BB in the late 80's, did you?  ;) )

Re: How much does size matter? Seat post help.
« Reply #10 on: 30 December, 2013, 02:40:18 pm »
Quote
Now that you're here: You didn't by any chance build frames with 4 or 5-digit numbers stamped underneath the BB in the late 80's, did you?   )

Late 80's was 4 digit numbers from about 3000 which was end of 87 to around 4400 whch was end of 89. I doubt your frame is one of ours as amost all of them of that era had a full set of braze ons as standard. If you can post some pics of the frame I will see if I can narrow things down a bit. Seat cluster is a good place to start, and dropouts/stays joints. Most framebuilders have a "style" some of which are easily identifiable.

Cheers

Dave Yates
It's not just hitting it with a hammer but knowing where to hit it and how hard

Re: How much does size matter? Seat post help.
« Reply #11 on: 30 December, 2013, 02:50:58 pm »
Obviously the frame is dead, and what you need to do is buy my Byercycles SuperTourist so I can buy a 29er and start doing solo 24hr off road stuff and MrsMekon can stop moaning about me not having sold it.

HTH

Re: How much does size matter? Seat post help.
« Reply #12 on: 30 December, 2013, 02:56:01 pm »
Obviously the frame is dead, and what you need to do is buy my Byercycles SuperTourist so I can buy a 29er and start doing solo 24hr off road stuff and MrsMekon can stop moaning about me not having sold it.

HTH

I've a better plan: tell her you've sold it and hide it at mine. I'll only charge you a nominal storage fee.  ;D

Re: How much does size matter? Seat post help.
« Reply #13 on: 30 December, 2013, 02:58:35 pm »
Actually, I may need to hide an MTB somewhere come the end of the month if I don't sell something. Mate is selling a Whyte 901 at a price too good to refuse, and I've been told "no, and what about that tourer and BMX you haven't sold that you said you would". Not quite sure how to reconcile that with the inevitability of the MTB purchase.

I'll bear your kind offer in mind.

Re: How much does size matter? Seat post help.
« Reply #14 on: 30 December, 2013, 07:41:26 pm »
I bought a seat post sizing gauge on eBay. Then I found out that the Colnago frame I'd been struggling to push a 27.2mm seat post into, had in fact, a 27.0mm seat tube  ::-)

New seat post ordered.
I am often asked, what does YOAV stand for? It stands for Yoav On A Velo

<Thread now very OT> Info about my frame
« Reply #15 on: 01 January, 2014, 04:35:46 pm »
Dear Dave et al,


This is my current spare commuter / pub bike. It's a lovely plush ride and is the bike which pretty much got me into regular commuting years ago, so has some sentimental value. As you'll see, it's due a respray and general do-up! If I can work out what make it is, may be I should have it resprayed with the original decals, in honour of the work it's done.

Any ideas? Can take more/better pics if necessary.


The bike, sans seat post...


Dropout/stay joints


The forks are pretty good, actually


Fork crown... Yes, I know I should get a bolt in that lamp boss! ;D


Top cluster


Bottom bracket area


Re: <Thread now pretty OT> How much does size matter? Seat post help.
« Reply #16 on: 09 January, 2014, 09:33:01 am »
Now then Alwyn,

Apologies for the delay, lost track of things recently. Your frame is not one of ours I am afraid. It is a standard issue late 70's early 80's "tourer"' . The components are what were generally available at the time ie Haden bottom bracket shell, Vagner crown, possibly Bocama lugs and Campag style forged dropouts so it could have been made by any one of several of the "batch producers" of the time We did not use Bocama lugs and virtually never fitted fork blade lamp bosses. The lower point on the bottom head lug has not been removed, which we always did to eliminate the stress raiser. All of our "standard" frames of this era were built using RGF bb shells, (some Haden shells were used )' Prugnat lugs and Vagner crowns with Campag or Shimano dropouts depending on what was available. The seat stay ends were always taken to a point rather than rounded. Incidentaly had you noticed that your left seat stay cap plate is cracking off the stay. If you are going to refurbish the frame  then you need to get this seen to. Worth doing as it seems a perfectly good frame.
In summary then, its not an M.Steel frame and because of the generic nature of the construction and components I am afraid I cannot pin down the manufacturer.

Cheers

Dave Yates
It's not just hitting it with a hammer but knowing where to hit it and how hard

Re: <Thread now pretty OT> How much does size matter? Seat post help.
« Reply #17 on: 09 January, 2014, 11:17:26 am »
The things you could tell from a few dodgy snaps.

Shows you what experience can do! <Where's that "impressed" smiley?>

Thanks!