After deciding to build this frame, I still have to decide on which parts to use. Do I stick with Campagnolo Super Record or do I go with something different like early Dura-Ace 7100/7200 DA-200? Or should I just go for a mismatch of components which was often the case to build as light a time trial bike as possible? There is a whole list of names such as Huret, Mavic, Modolo, Gipiemme, Omas, Edco etc that could be used to build this bike.
First thing first though, and that is choosing and fitting a headset. You cannot build a bike without first joining the frame to the forks. This is always the first step I take in any build. I found a lovely (and cheap) Stronglight A9 headset on eBay for an excellent price!
This is a roller bearing headset as opposed to the more widely used ball bearing alternatives. This type of headset can handle the load that a headset needs to take much better, in my opinion, than ball bearings. The weight of this headset listed on Velobase is 79.5 grams. I already have a black Edco Competition headset that was favoured by the SBDU, listed as 109 grams on Velobase.
My non precision kitchen scales show the Stronglight at 81 grams and the Edco at 112 grams. If the Stronglight headset has the right stack height then I’ll go for that.
Total stack height is the lower headset stack height plus the upper headset stack height. Rather than trying to explain how to measure stack height, here is a excerpt from Sutherland’s Handbook for Bicycle Mechanics 4th Edition.
Several online sources list the overall stack height of the Stronglight A9 as 40 mm. Most high quality 1″ headsets of this era will have a lower stack height of approx 14 mm; in fact, frame builders will take this vital measurement of 14 mm when designing frame and fork geometry. Using the guide above, my measurements came out at…
C lower stack = 13.79 mm
B upper stack = 26.22 mm (27.22 mm less the 1 mm lip on lock nut)
This gives a stack height measurement (A) of 40.01 mm – matching what I found online.
Now that the stack height is known, it needs to fit the length of available steerer column. You can do as the guide above suggests, or, as I do, simply measure the total length of the head tube and subtract that from the total length of steerer on the forks. If the resultant measurement is greater than the stack height or no more that 2 mm less than the stack height, you should be ok. My measurements are…
Total steerer column length = 173 mm
Total head tube length = 133.46 mm
Available steerer length = 39.54 mm
That tiny difference means that this Stronglight headset should be a perfect fit without any additional spacers or cutting. Now that the maths is out of the way, I can get on with fitting it!
The A9 roller bearings sit between 2 light alloy bearing surfaces, which in turn, sit inside the bearing cup and provide a very smooth headset. As there are no external markings or names on the outside of the lower cup, it doesn’t matter which way you position it before pressing it into the frame.
The upper and lower cups of this headset don’t have any steel bearing surfaces pressed into them – the bearing surfaces are separate and sit either side of the bearing. This means that the cups are simply very light and very thin machined alloy which can be easily deformed and damaged. I cannot stress enough how good tools should be used when fitting high quality components like this.
Just some light grease and the headset is ready to assemble. I’ve used some multi purpose grease – I didn’t want the grease to be too thick and wasn’t too bothered about it being waterproof as this isn’t going to be a standard road bike or training bike subjected to all the elements; just enough of a light coating to cover everything.
There are no marks whatsoever on this headsets bearing surfaces and once adjusted, it is very smooth and looks great! Now that the frame and forks are together, I can continue the build.
I have an Omas Titanium bottom bracket, which I’m hoping to fit next once I source and fit new bearings.