Bike Medicine Purple Extreme Synthetic Lubricant

Bike Medicine Purple Extreme Synthetic Lubricant was originally designed for working in industries where conditions are very harsh – offshore oil rigs, mining, and the like – and it brings a fair bit of that robustness to your humble bike chain. It works well in the dry, less so in the wet I found, and in both conditions it struggled to reach the quoted application mileages.

Over the two-month test period I have applied Purple Extreme to a range of different test bikes, all of which arrived with brand new chains. After a full clean of each chain before application, I found the lube easy to apply, with little in the way of excess drips, showing how well it is penetrating into all of the little nooks and crannies.

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Bike Medicine says you can ride your bike straight away after application, but it's best to leave it overnight if you can. It's a lightweight liquid but the solvent evaporates, leaving what it calls the Extreme Pressure additive in place, with a much drier look and feel to it.

Large chunks of the test period saw dry roads, and on these the Purple Extreme lasted well, with the chains remaining clean and not picking up much in the way of dust and dirt. Both of the road bikes I was testing it on required another application after around 250 miles as the chains were starting to sound a little dry and squeaky – much less than the 400+ miles claimed by Bike Medicine.

There was also a patch of weather that meant a coating of salt on the main roads, with a resulting spray of sludge that just eats components. A new application of Purple Extreme to the road bikes stood up well – the chains did get dirty, but leaving them in the shed for a couple days to dry out didn't see any rust forming, unlike another road bike I was using that still had the original manufacturer coating on it.

The chains cleaned up easily too, with just a wipe over, and only felt like they needed relubing after around 150 miles.

In the wet and mud I wasn't so impressed, though. Using Purple Extreme on a gravel bike and taking to the trails, my drivetrain would already be noisy by the end of the route.

It wasn't raining as such but there was spray coming up from the short tarmac sections and it had been raining previously so there were some quite deep puddles. The rest of the route is a mixture of gravel, chalk, grass and mud, and it's always a challenge for any lube.

I rode this same route, which is 33 miles long and takes about three hours to complete, three days in a row, setting off each time with a new application of Purple Extreme. Returning home after each ride, the chain was sounding rough and dry.

Sticking to the road it fares a bit better in the rain. I was getting around 150 miles between applications in the wet, though it's always difficult to gauge, with conditions being so variable.

Value

In the UK this 120ml (4oz) bottle costs £13.49. Bike Medicine recommends a typical road or mountain bike chain requires 1/4oz, about 7.5ml, of lube per application, so that's 16 applications from a single bottle. In wet conditions, or on your gravel bike, you are going to use it up quicker than Bike Medicine suggests.

> Buyer’s Guide: 10 of the best bicycle chain lubes

It's still not overly pricey, though. Wolf Tooth also makes big claims about 400+ miles between applications of its WT-1 All Conditions Chain Lube, and while Neil was very impressed with its ability in all kinds of weather, it is £19 for just 59ml.

Green Oil's Wet Chain Lube is £7.99 for a 100ml bottle so a bit cheaper than Purple Extreme, and will last for around the same sort of mileage in wet conditions.

Conclusion

Overall, I wouldn't say that the Purple Extreme is quite as good as claimed, at least in general UK conditions. But accept that you'll probably be applying it more often than it says on the bottle, and when it is working it's doing so very well. Your chain stays surprisingly clean and quiet. And quiet means less friction, so your chain will last longer.

Verdict

A good lube for the majority of conditions, though it doesn't achieve the mileage claims