After recently purchasing a Busch & Müller dymotec 6 dynamo, I found the noise level increased dramatically during wet weather. Going from a low hum in the dry to a higher pitch tone in wet weather.
Initially I thought this could be down to the rubber roller slipping against the tyre tread wall, so I increased the pressure - but still the noise continued in wet conditions.
I had seen the Busch & Müller all weather dynamo roller advertised on evans cycles website, but it seemed steep to charge £11 for an item, that was a simple wire roller replacement.
I then spotted this item for sale on ebay (used briefly by the owner), and promptly won the item for a total of £1.99.
When this arrived it looked to be in as good as new condition, so then waited for the next downpour before giving it a road test.
With a flat head screw driver I removed the existing plastic cap, and metal fixing clip holding the original rubber roller, finally taking off the rubber roller itself.
I replaced the wire roller and metal fixing clip (easing this on with the flat head screw driver) and put the plastic cap back on which clicks into place.
This took less than a minute and so could be done by the side of the road, if a downpour hit without warning.
The most important thing is to make sure that the wire roller is aligned exactly with the dynamo tread in the tyre (Note: this wire roller cannot be used on thin skinwall tyres), and that the pressure on the tyre side wall is fairly light.
The best thing about this was the dramatic noise reduction. The difference was stark and the grip it had to the tyre was incredible, and my early morning ride was a pleasure now the high pitch tone was reduced back down to a low humming sound.
I'm almost tempted to use this all the time, but I can see this wearing the tyre wall down quicker than the rubber roller and Busch and Müller recommend only using this in wet/snowy conditions.