mynewnchome

Well, mine gave up today, appears the threads aren't holding.

Says 34 on the bottom, just trying to make sure I get a correct replacement. Came of a Raleigh Revenio 1.0.

Recommend a good replacement? Allen key or quick clamp?

fietsbob

# 1 measure what tube diameter they fit over ..... and 2, look for those with a steel insert for the bolt to screw into, rather than just threading the aluminum.

mynewnchome

I read this on chain reactions site:

So I'm thinking the 34.9mm would be the right one? I measured it using the good ole USA standard, it measures 1 3/16" of an inch inside diameter as best I can tell with a ruler. The web says that's 30mm.....so I'm curious if it's 30 or 34. You can probably tell I didn't excel at the metric system but I'm trying.

mynewnchome

Interesting.....seat tube measurement does measure smaller....

Specs say this was in this model bike:Alloy Micro Adjust 27.2x300mm

fietsbob

Tube diameters (Other than French) are predominantly Fractional- inch , but stated in metric equivalencies..

27.2 is probably the seat post diameter, , so tube bored out to that inside diameter.. says nothing about the outside..

might be time to buy a proper caliper,

AnkleWork

So close . . . then that sudden swerve off course.

Andrew R Stewart 

Using a wooden ruler to measure a dimension that usually has a decimal point aspect is not the best. Assuming you don't have, or don't want to spend the $ for, a caliper one can wrap a strip of paper around the tube and mark the start and stop of one circumference. Then unwrap the paper and now use that crude device (the wooden rule) to measure the circumference. Divide that by 3.1415 (pi) to get a tube diameter. At least you will reduce the error by about a factor of 3.

It is common for manufacturers to short cut labels, that "34" could mean 34.9 in that brand's nomenclature. But who knows? The only true fact is what the measurement is.

Knowing the tube's ID (27.2 as example) says nothing about the tube's wall thickness or it's OD.

Only 5 ODs? I wish this was so. My externally butted steel frames have a 29.mm OD, Traditional French steel frames often are 28mm. Just two that defy a published and too simple a statement.

If you can't see your way to measure better then go to a LBS. They should have the know how and caliper to measure and, hopefully, have the actual clamp in stock to confirm fit. Then buy it from them as they have done work for you. Andy

Binky

Just drill it out and put a nut and bolt through it, or one of those cam locks like this:

pdlamb

If you're going to save money by measuring with a wooden ruler and converting to metric, budget for 3X shipping and handling (buy one, return it, buy another one).

Alternatively, you could buy a decent caliper (maybe $30) and measure the outside of your seat tube (not seatpost!) accurately.

Of course, caliper and the right clamp would cost more than the full list price your LBS would charge you to measure, possibly order, and install the new clamp.

Or go to your hardware store and buy a nut and a longer bolt (approximate cost, $1).

AnkleWork

In this case a simple strip of paper, pencil, ruler, and arithmetic will suffice -- and who wants that?

(Also, a plastic vernier caliper can be had for about $2 which is fine for this application, but . . . )

fietsbob

BTW The Kalloy made clamp used by Bike Friday is also showing a 34 on it, But it is also showing marks that the Piece was then machined

to a specific inner diameter .. Of tubing it was made to fit over..

so , I'm guessing here. it may be a maximum as to how much it can be bored out ..

This bike has a 1.25" steel tube used , in metric speak that's 31.75 mm .. thickness of powder coat brings that out to 32..





....

mynewnchome

Ok, forgot I had this caliper, thanks for helping, everything, seat post and clamp, measures as shown.

My local LBS is a pretty good drive and the work schedule is making it tough to get there, looked at this online, thoughts?








Seat post


Clamp

Ignore the dial, I forgot to set it prior to measuring, the 31ish is in mm scale.

fietsbob

31.8 fits over a 1.25" tube.. you did measure the frame tube? right?

mynewnchome

Yes, the caliper at 31 is seconds after removing from tube.

pdlamb

The paper strip idea might work, although there's a large fraction of the population who will tremble at the idea of using math. (I memorized the first 12 digits of pi years ago, but I try to be nice to the math-phobes.)

I have a plastic caliper. I've found it's about as accurate as the wooden ruler that started this thread. Just a plastic knob on the end, instead of the wheel a decent vernier has; push the knob with the same force I'd give a metal vernier and the caliper distorts pretty badly, giving me a spurious reading.

HillRider

You could probably salvage the current clamp by drilling out the stripped threads to a clearance hole for a 5 mm or 6 mm bolt and replacing the current bolt with a longer one and adding a nut at the far end.

12boy

Any bolt that wil fit through the clamp and come out with enough threads to hold a nut will do. If the nut side is too roundy file it flat and throw on a washer and a nut. Then save your pennies and get one with steel threads or even all steel, which takes repeated tightening and loosening better. Look up Worldwide Metric Conversion....it is the easiest one to use I have found.

fietsbob

conversion math 1" = 25.4 mm 1/8" = 3.175 mm ...

AnkleWork

Arithmetic isn't exactly mathematics, so don't be scared.

Also, any tool has to be used properly in order to be useful.

fietsbob

I have a Swiss made plastic dial caliper , it's quite adequate to 0.1mm.. not 0.01mm..

AnkleWork

Yeah, mine will resolve 0.05mm and with calibration and careful use you can keep the error within that. A great thing about Vernier scales is that you can get a real feel for the magnitude and "sense" of errors.

AnkleWork

+1 A permanent solution, especially with a lock nut, or a QR set-up. Based on the pic, filing the place where the nut will bear is probably needed to avoid bending the bolt too much.

On a tangent, converting a seatpost collar to through bolt can be an elegant solution for securely mounting a rack to a frame without braze-ons (if the frame size works with the rack mount).

alcjphil

Ok, What I think is that the OP has a calliper to take a measurement, but is taking the wrong measurement. The measurement that should be taken is the outside diameter of the seat tube, not the inside diameter of the seat collar which expands when the collar bolt is not tightened.

mynewnchome

The first picture with nothing in the jaws is lifted straight off the tube, the collar measures the same in the open position it's in.

fietsbob

So you replaced it yet? or is it too snowy ?