Nasty noises from a forgotten component

Roberta returned from her emergency visit to Roberts with gleaming silver cranks and running oh so sweetly. Unfortunately this happy state of affairs only lasted a few days. Her cranks still gleamed but suddenly, without warning, she started to sound like a sack of spanners! One minute I was riding happily along, the next she was producing horrible grinding/crunching noises as if she was about to spit bearings out all over the road. I changed gear a couple of times and the nasty noise went away. What on earth was it?

It was obviously coming from the transmission and as the cranks had recently been replaced the bottom bracket appeared to be the prime suspect. Everything there was nice and tight, there was no play anywhere and no loose chainring bolts. Not that then. It didn't occur regularly, sometimes I could ride for several miles with no problem and then suddenly that horrible noise again. I tried my favourite policy of ignoring it and seeing if it went away. It didn't. It started to happen more often and loudly enough for pedestrians to turn their heads and stare. How embarrassing, my lovely shiny steed making such noises! I now had a spacer in my bottom bracket that hadn't been there before, perhaps that was the cause. Maybe it had altered the chain line just enough to make a difference to a well used cassette and chain. It wasn't a great theory but it was the only one I had. I fitted a new cassette and chain, crossed my fingers and went for a ride. For a few miles I thought I'd cracked it, but no there it was again, crunching and grinding as I desperately changed up and down the gears until it went away.

This continued for a couple of weeks. Most of the time it was fine but I was constantly on edge waiting for that horrible crunch. I couldn't seem to discern any pattern to it, sometimes it happened when I was putting pressure on the pedals and other times when I was just cruising along after I'd been freewheeling. Slowly the penny dropped, it was the freewheeling that was the key. It happened mostly when I resumed pedalling after a long freewheel. It had to be the freehub, that mysterious mix of pawls, ratchets and springs that I had never given a moment's thought. I have a second set of wheels so I put them on to test this theory. Ten miles pedalled, still no noise. Twenty, thirty, forty miles and still running sweet as a nut. I'd found the culprit.

The next question of course was what to do about it. My knowledge of freehubs was sketchy to say the least. I knew they contained pawls and springs but I didn't really understand what a pawl was, much less how to replace it. Should I just take the wheel into my local bike shop and leave them to it. It was an appealing idea but then I would never know what its innards looked like or how they worked. My hubs are Novatech (also marketed as Ambrosio Zenith) but there seemed to be lots of different models and I didn't know which was mine. A search on the internet came up with someone else who'd had a similar problem and eventually solved it by phoning Harry Rowland who'd built the wheels. I decided to do likewise. Harry was very helpful, assured me that I was most unlikely to need a new freehub – all it would need would be a good clean – and that it was easily removed with a 5mm allen key and a 17mm cone spanner. He made it sound so easy but I wasn't absolutely convinced. Just because he could do it in his sleep did not necessarily mean I could do the same! Still, as I had 2 cone spanners that I've never used and nothing to lose I gave it a go.

As Harry had said it was quite easy to remove and looking at the watery black gunk that it was full of I'm not surprised it was making nasty noises!

Freehub maintenance 001

Freehub maintenance 002

Not a pretty sight

I'd expected that tiny parts would fly out everywhere, never to be seen again but it was surprisingly easy to clean and replace the pawls – I now know exactly what they look like and how they work! They weren't chipped or damaged at all, just filthy. This would no doubt have been a good time to replace the bearings as well but they didn't feel too bad so I decided to quit while I was ahead! Cleaned up and regreased it looked completely different. Harmony has now been restored!

Freehub maintenance 003

So that's what pawls look like!

3 comments on “Nasty noises from a forgotten component”

  1. Patrick wrote:

    Nice one Hilary.

    Re: ... there seemed to be lots of different models and I didn't know which was mine.

    That is often the problem with DIY bike maintenance – knowing which part to get. Having recently replaced a headset (using a home-made headset press) I thought I'd now done everything, but I'd forgotten the freehub! The pawls bit – is that a new one or the old one cleaned up?

  2. Hilary wrote:

    The picture is the old one cleaned up – does look a bit different!

  3. Rachel wrote:

    Nice job Hilary. To be honest I normally just replace a faulty free hub body.
    It is possible to rebuild lots of stuff if you have the patience.
    Nice to meet a fellow female tinkerer too.
    There really should be more of us.

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