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Sunday 16 February 2020

Replacement headset and forks

Shelley's bike had two issues. It had started to pull to one side and the steering was very rough. In addition the forks were not performing as they should.

Today Dean and I fitted a new headset and new forks. Mainly I watched and learnt while Dean fitted them.

The forks came out easily. The bottom bearing came out just by pulling however the top bearing fell apart and the casing had to be levered out.

That bearing probably had a lot to do with the poor performance Shelley had been experiencing.

Getting the old bearing cups out was tricky. I tried with a bearing cup removal tool and just managed to bruise my knuckle. Dean removed them by drifting them out with a punch a little bit at a time, round the edge.

To fit the new one, we put the cups in the freezer for half an hour and used a heat gun to warm the head. We were not sure how much that helped but did it anyway.

Inserting the cups straight was the tricky bit, even with a bearing press.

We cut down the fork head tube to the same length as the forks that had been removed.

I used a star nut inserting tool to get the star nut in to the end of the tube.

To fit the crown race on to the fork crown we heated that slightly and used a home made tool, made out of a large aluminium tube, to seat it. The end was ground down, to fit over the angle on the crown race.

We greased the bearing cups and inserted the bottom bearing and the fork tube, followed by the top bearing, the split upper race, the spacers, the stem and finally tightened the top cap to pull it all together.

Fitted the brake and the wheel.

Once on the ground, Dean straightened the handlebars and tightened the bolts on the stem.

Job done.

We set the fork damper up for Shelley and she took it for a test ride up the driveway. She was very pleased with the improvements.


Merida ONE-TWENTY 7.800 model year 2015

Forks: Taper tube 1"1/8" to 1.5"
FSA Headset
Frame cup diameters:
Upper: 44mm (43.7mm measured. 44.1mm cup fitted)
Lower: 55mm (54.9mm measured. 55.1mm cup fitted, FSA H5064)
Upper: 41mm O/D (40.9mm measured) 7.3mm thick. 45 deg outer and 36 deg inner angle. (FSA MR0401-1/8)
Lower: 52mm O/D (51.7mm measured) 7.5mm thick. 45 deg outer and 36 deg inner angle. (FSA MR019 1.5)


SR Suntour Aion 150mm travel. 27.5" wheel. 100x15mm axle.


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