Tag: maintenance

Threadless Headset Adjustment

It has been so long since I posted here I am shame-faced. Worse, we have not been out on our Thorns since we returned from our tour of Spain and Portugal in October 2014. But, hayho, cycling is a part of life and sometimes life gets on top of you. No point in beating up on yourself – learn and move on. Show yourself some compassion. 🙂

So, when I came to check the bikes over before setting out on our first day trip, needless to say there were some mechanical matters that needed attention. In order to box them for the flight home I had needed to remove the headsets and turn the handlebars through 90 degrees. Once reassembled it was clear all was not well as on both bikes the headsets showed way too much play and the forks seemed loose under braking.

Now this turned out to be an easy fix, but it was anything but while I was labouring away in my complete ignorance of headsets and their operation. The more I adjusted, the less success I had: all sorts of fears began to rear up in my head – each involving a more expensive repair that the one before. Who came to my help?  Well, Jacqui of course! Have you tried YouTube she asked?  Of course – silly stressed me had lost touch with my watchword – if not YouTube the Google will know what to do.

So it proved to be. I was lucky enough to come across “Wheelie Pete” and his YouTube channels. His bicycle repair videos are a delight: not only do you learn what to do, but also why you need to do it.

I watched his headset adjustment video a couple of times and headed to the bikes knowing what to look for, what to do and how to test that all was well after the adjustments.  Brilliant tutorials – clear, comprehensive, well-paced and delivered with an easy to listen to voice. Perfect! Needless to say, I checked out some of his other offerings and subscribed on the spot.

Here is the headset video I used:

Needless to say, after the job was done, I strutted my stuff for the rest of the day. Man fixes Machine: machine works properly.  Cue the sound of fists beating on chest!

Ah, the joys of Shimano Cartridge Brakes

I had promised myself I’d change the brake pads on our Thorns before our trip to Spain in late September.  It was not a job I was looking forward to.  I am not one of the world’s natural mechanics.  My projects often end in disaster, with the original problem half solved, but another two new problems created.

In my experience fettling brakes can be a time-comsuming and fiddly job.  Not so with this marvellous Shimano cartridge system.

Shimano Deore M590 V Brakes

Both of our Thorn Raven Sport Tours are fitted with Shimano Deore M590 V brakes. They work wonderfully, giving super stopping power and great confidence.  However, after a year or so they were showing signs of reduced performance, especially on Jacqui’s bike.

The for a change

Inspection of the pads showed that the wear levels differed, but all were approaching the limit marks and some were unevenly worn or badly scored.

In some ways the worst bit of the job was deciding which replacement pads were needed.  Unless you know the model name of your brakes and the pads required you are faced with a welter of options when ordering online.  A good tip if in doubt is to remove one of the original cartridges. (I assume cartridge is the new speak name for pad!)  Ours were clearly marked on the reverse – S70C from Shimano.

What I was not prepared for was the price – I paid over £30 for the four pairs needed from SJS Cycles.  That seems a lot of money for 8 small blocks of rubber like material!

However, working on the bikes was a treat.  All you need is a bull-nosed pliers or a small awl to remove the retaining pins on the pads.  Pushing them upwards then pulling with the pliers to extract them worked for me.  The pads can then be pushed out – towards the open end of the grooves they sit in.

One of the sources below delivered the best tip – remove and replace one pad at a time.  That way you cannot muddle up the right and left pads or fit them facing the wrong way.  Remember to fit the new retaining pins that come with the kits.

I was delighted to find that the new pads slipped into place without needing any further brake adjustment in all but one case.  All that was necessary was to release the brakes using the quick release mechanism.  There was no need to remove the wheels or to dismantle the brake pad assemblies.  As a result the whole job took only 20 minutes for all four sets of pads.  Simples!

I looked at these YouTube videos and sources before starting and found them all useful:

Jim Langley on Brake Maintenance

The Cycle Systems Academy

The Livestrong Guide

Maintenance: Adjusting the Chain Tension on a Thorn Rohloff Bicycle

These instructions are adapted from the advice provided in the Thorn Bicycle and Tandem Owners’ Guide.

When and how to adjust the eccentric bottom bracket

According to Thorn,  slack train will not do any damage whatsoever, if it is allowed to become very slack the only danger is that it may fall off. By contrast, a chain which is too tight wears prematurely, causes premature wear to the bottom bracket assembly (possibly to the hub too) and causes unnecessary expenditure of energy in use. It’s not a good idea therefore to adjust too often or to over adjust: better to err on the side of, “if it’s not broke, don’t fix it.”

According to Thorn, here is always a “tight spot” on all chain drive systems. When setting chain tensions there must always be some slack in the chain at this “tight spot”.  To find the tight point, measure to the mid point between the centre of the sprocket and the chainring.  Measure how far you can pull up the chain at this point and work round the chain until you find the point where you can lift the chain the smallest amount.  This will be the tight spot.

We will call the gap between the highest and lowest point the chain can reach when pulled up and down, measured at the mid-point, T1 and the gap when pulled together, T2.  See here:

Chain Diag

Do not readjust the chain tension until T1 minus T2 equals 40mm. The “crude but simple, reliable and effective” system Thorn use for locking the eccentric depends upon the points of the screws being able to bite into the alloy eccentric. If unnecessary chain adjustments are made, the holes created by the points will be too close together and the eccentric will simply slip back into its previous position.

The change should be adjusted before T1 minus T2 reaches 60 MM. Failure to do this makes it possible for the chain to become slack enough to fall off the chain ring (or sprocket).

With a new chain (and especially a whole new transmission), it may not take very long for the 40mm of slack to become 60mm of slack but this situation will improve dramatically with the passing of the miles.

Adjustment is Straightforward

To readjust the transmission chain tension on Rohloff Thorn cycles

  1. Unscrew the eccentric screws, using a 15mm spanner or large screwdriver.
  2. Rotate the eccentric to achieve the desired chain tension using the adapted spanner provided by Thorn. Depending on the model of eccentric shell fitted to your cycle you will need to use either an eccentric adjustment spanner or by inserting a metal rod. Using the spanner set simply rotate the eccentric to achieve the correct chain tension.
  3. Finally re-tighten the eccentric screws and re-check the tension of the chain.

Thorn provide these eccentric screw torque settings for Rohloff equipped cycles:

10 to 17  Newton-meter (torque)
7.38 to 12.5 for foot pound force.

Rohloff Hub Oil Change

This is an excellent video created by Thorn Cycles showing how to change the oil in the Rohloff hub in the clearest possible step by step guide.  Very reassuring for the less than technically minded like myself.

A similar video (in Dutch) can be found here:

The oil needed to be changed every 5000K or each year.  Keep records for claims reasons.  Rohloff provide a record card for this purpose. Assuming you have the Rohloff Oil change Kit (available from Thorn/SJS Cycles) the steps needed are:

  1. Clean the Hub surface.  Keep a rag to hand to catch any oil drips.
  2. Remove the drain plug (note the necessary 3mm Allan Key is not provided in the kit and you want to have a decent one as the plug is difficult to budge at the start.  Moving the plug to the 2.30pm position makes it easier to clear the bike rack if fitted)
  3. Draw 25 ml of cleaning oil into syringe and attach the drain tube. (Twisting the tube allows it to act as a ‘driver’ while you guide it with your fingers.)
  4. Push the cleaning oil into the hub and draw out 20ml of air.
  5. Replace the old drain plug (adding a blob of petroleum jelly to the end of the Allan Key will help get it into place.)
  6. Ride for at least 1K or spin the hub for 3 minutes while switching between gears 3 and 5.
  7. Refit the drain tube and leave pointing downwards for 15 minutes.
  8. Draw off the dirty oil.  Leave for a further 5 minutes to drain. (Expect to get between 35 and 50ml of oil out.)
  9. Dispose of the old oil in the container provided.
  10. Draw 25 ml of new oil into syringe and attach the drain tube. (Thorn say 15ml is enough, but I went with Rohloff’s recommendation.
  11. Push the new oil into the hub and draw out 20ml of air.
  12. Put the new drain plug into place (take care not to ‘cross-thread’ it and expect a little resistance as it comes with some sort of ‘wax’ to seal it.
I know myself to be a pretty feeble and nervous ‘mechanic’, but this procedure was very straightforward.