Saturday, 16 May 2015

A little trip to Cromer

An evening ride to Cromer revealed a front brake that was much better, but which now had too much lever movement. Nipping up the adjuster two clicks improved the lever movement and there didn't seem to be any brake binding, which was excellent. There was still a juddering from the front, particularly on braking. Getting it home, I found that wheeling the bike backwards revealed that particular groan that only binding brakes make, so I've backed the adjuster off one click.

Back in the workshop, a quick check revealed loosened head bearings - wheeling the bike forwards and putting the brake on reveals a 'jolt' from the headstock which you can hear. To check them more physically, put the bike on the main stand and put your thumb here in the dim & dark recesses of the top yoke, across the gap between the dust cover and the headstock:

The Engineer's Thumb

With your other hand, grasp the front wheel and rock the bike backwards. This has the effect of pushing the steering column up through the headstock against the weight of the bike, and your thumb will be able to feel any movement. Don't vigorously rock it backwards & forwards - you don't want it rolling off the stand.

Mr. Waller suggests lifting the weight off the front wheel to perform this job, bit since I have no bike lift or any desire to damage my back I use the method described above.

So, having found some movement we need to sort out the problem. First slacken off the lock nut under the top yoke with your head race spanner, Clay at Acme Stainless has these, but you can also pick original ones up on eBay. Be very careful not to damage the paint on the tank - make sure the spanner fits well (so that the spanner doesn't slip) and that the tank is protected (for when the spanner slips):

Now, grasping the wheel again, roll the bike backwards against the main stand whilst attempting to tighten the lower of the two nuts. You will find that the nut is now loose and can be tightened down - you will want to perform this feat of coordination two or three times.

When you are happy that the bearings are snug, and you can feel no more movement, tighten down the top nut. Move the handlebars and satisfy yourself that they are not binding anywhere. 

If you use your steering damper, reset it and you are good to go.

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