Author Topic: Mercury Mk 3 Tyre Choice  (Read 5992 times)


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Re: Mercury Mk 3 Tyre Choice
« Reply #15 on: November 13, 2022, 11:31:03 am »
I ordered my Mercury with 50mm G-Ones and Thorn supplied them tubeless with no recommendation for tubes. I've only had to make one repair on the road, and as it was a front tyre I coukd see it was holed by the sealant spraying gently from the tread. Easy therefore to find the hole, and with enough air pressure still in the tyre that it was easily plugged. My guess is that 700c x 40 would have enough volume to work this way also.

By way of contrast, I left the rear tyre sealant unreplenished for six months or so and one day picked up a small puncture that didn't make itself obvious on the road and yet didn't quite seal. The tyre deflated fully overnight in my garage, and I could not remount it with a garage-style hand pump. I added some sealant and took the wheel to my local bike shop, which mounted the tyre with a compressor. I'd taken plugs with me, expecting that leaking sealant would reveal the site of the hole. But the fresh sealant had immediately sealed the leak, and that tyre ran unplugged for several more months until tread wear led me to change it.

That is exactly why I doubt I will ever go to tubeless.  You need to maintain your sealant.  How often, that is something that I do not know but I have heard at least once a year.  I live in a part of the world that most people only bike about six months of the year, so once a year might mean six months.  (It snowed here yesterday, most people put their bikes away for winter weeks ago.)

I average one puncture a year.  And I always carry a spare tube on each bike, a puncture is not a big problem for me.  And in an average year I ride five or six or seven different bikes, thus maintaining sealant in that many bikes would take a lot more time for me than dealing with an annual puncture. 

And one bike is shod with studded tires in winter, regular tires in summer, thus two tire changes each year on two wheels.

Even if I only put sealant in the three bikes that I ride most, that is still maintaining sealant in six wheels which is a lot more time consuming that dealing with one annual (on average) puncture.

For those that get a lot of punctures and do not have many wheels to deal with sealant maintenance, tubeless might be great, but it is not for me.
« Last Edit: November 13, 2022, 11:46:35 am by mickeg »

John Saxby

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Re: Mercury Mk 3 Tyre Choice
« Reply #16 on: November 13, 2022, 07:43:25 pm »
+1 for Mickeg's POV.

I'd like to say that I reached that conclusion from due consideration of mechanical principles & practice, but inertia is probably the key force at play.


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Re: Mercury Mk 3 Tyre Choice
« Reply #17 on: November 13, 2022, 08:19:36 pm »
I do not understand the tubeless trend and I can only speculate that it is driven by the combination of demand for mtb bikes and manufactures wishing to simplify their production lines.

We have not had a flat on our tandem in over 8000 miles on many different surfaces of heavily loaded touring. I do check the tires on occasion for glass and wire. It is frustrating that tubed tires are being displaced. The recent Supreme cancellation is another blow. I do not wish to use “tubeless ready” with or without tubes because now I must deal with complications fixing very tight tires on the road.

Tire manufacturers will go with trends. However, most people with bikes will eventually neglect maintenance and then be frustrated to find their tires flat owing to sealant issues. Perhaps that will save the day…eventually... and manufactures will continue tubed tires.


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Re: Mercury Mk 3 Tyre Choice
« Reply #18 on: November 13, 2022, 08:50:05 pm »
Re Thorn going to light tubes with sealant as its recommendation over tubeless,
Thanks, I now remember reading that's what they'd changed the recommendation to, but I'd forgotten.
It strikes me as an odd combination, the big advantage of tubeless, at least as the manufacturers are prompting it, is the ability to run lower pressure without risking pinch flats.  Using a tube negates that whether it has sealant in it or not, it's not something I'd consider.  I'd only choose tubeless for reasons of improved ride quality rather than puncture resistance and I'm in no hurry to try that. I do use lightweight tubes, the only disadvantage is they require more topping up, but I do that routinely anyway.

My leisure mileage is well down this year, for various reasons, somewhere around 4,000km, and I haven't had a puncture yet.  I've only had one on the work E-bike in around 5,000 km and that was a slow overnight deflation.


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Re: Mercury Mk 3 Tyre Choice
« Reply #19 on: November 13, 2022, 10:51:45 pm »
The ease of inflating a tubeless tyre depends on the tyre and rim combination. While my Mercury came with tubeless tyres they were on Thorn 584 rims which aren't tubeless ready I had to get a booster tank to get 50mm G-One Speed tyres to seat on the rims but I completely failed to seat 48mm Gravelking SK tyres which were a slightly looser fit as the air was leaking through the gap between tire and rim faster than the blast from the air tank could get into the tyre. Extra rim tape was added into the central depression in an attempt to make a tighter fit but wasn't successful.

When I did another bike build I used wheels I already had which had American Classic Hurricane rims which had come with tubes but I discovered that they were tubeless-ready and fitting tubeless tyres onto those was easy. My latest bike fiddling uses Kinlin TL-21 rims which are ideal as the flat areas each side of the central depression slope very slightly towards the edges. Provided the tyre sits on those flat areas when initially fitted onto the rim then there's already a fairly good seal and the tyre can be easily inflated with a floor pump.

Very interesting on the rim differences, John. When I mounted a Rene Herse tyre on the Thorn rim I couldn't get it inflated when tubeless even with a mains-powered compressor and tank. Rene Herse says its tyres are sized accurately but many rims aren't. I found it hard to believe that the Thorn rim flats could be so undersized, especially given the G-Ones went on tubeless okay, but your info here is very helpful on that front.

Interestingly, the fine print on Rene Herse Extralights recommends running them with light tubes. Of course this makes the whole package nearly as heavy as the G-Ones with sealant. What's the point of the extra-lightness then? Well it's the extra flexibility of the carcass, which a tube doesn't seem to compromise much. I ended up fitting a Rene Herse to the rear (only) and using a normal-weight tube I had lying around. It's easy to suspect confirmation bias but my initial impression was significantly improved speed and comfort just from the rear change, with the G-One still in the front.

I'm not quite sold on the Rene Herse rubber as a continuing thing though. I'll get some light tubes, add the front one when the forward G-One wears out, and report when I've done some more running. My intuition at this point is that as nice as the RH rubber might be to ride on, the G-Ones are still very good. And with only one set to keep topped up with sealant, I love the ease of repair at the roadside, the extremely light weight of even several plugs, and the likelihood that a single spare tube would cover me for emergencies on a multi-day trip spent outside of the city. But we'll see.
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Re: Mercury Mk 3 Tyre Choice
« Reply #20 on: November 14, 2022, 09:50:06 am »
I don't have ready access to a pressure tank, I have a generic CO2 inflator that disgorges a good volume of gas quickly but I doubt it would have enough grunt to seat the G-Ones on my DT Swiss 460s.  So, I think of necessity it will have to be tubes.  The Mercury rolls OK on the Marathon Plus tires, so should be even better on the G-Ones.  I will try that this afternoon and report back once I have pushed some miles underneath the new rubber.
« Last Edit: November 14, 2022, 09:51:52 am by SteveM »


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Re: Mercury Mk 3 Tyre Choice
« Reply #21 on: November 16, 2022, 02:30:14 pm »
Here's a good article on the tubeless subject .

In my limited experience I've found that the right tyre - rim combination make tubeless operation more viable both because inflation is much easier and, once inflated, the tyre beads lock into the rim hooks and stay engaged even if there's a major loss of pressure.
It's also possible to add another layer or two or tubeless rim tape to help the tyres have a snug fit onto the edges of the rim which in turn makes inflation with a simple pump much easier.

If touring on a heavily loaded bike then the weight, performance and comfort advantages of tubeless are much less than if on a lightly loaded day trip.


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Re: Mercury Mk 3 Tyre Choice
« Reply #22 on: November 16, 2022, 09:04:09 pm »
I know some mountain bikers that love tubeless.  And in the southwestern USA there are a lot of thorns (the biological kind, not the bike kind) and puctures can be frequent.  I know one guy that rode his road bike in the southwest on a highway, punctures every day, one day he had seven punctures.  Where there are that many thorns, I would be inclined to use sealant in a tube.

In all of my touring, I have had one puncture and tubeless might have sealed that up.  But it was not that troublesome to change a tube that day.

I have read a lot on road bikers on skinny tires trying tubeless and sometimes in corners the tire can have sudden loss of pressure.  And I have not yet read of any compelling reason for anyone to use tubeless on a skinny tire road bike. 

But, some of the people that use wider tires, they really like it.  My opinion is good for them.

I have built up four wheels in the past half decade when tubeless was starting to be common, thus I found that I had to research the rims I was buying if I wanted to stay with tubes to make sure I did not accidently get a tubeless type rim.  As noted above, a rim might work with tubes, but it will be tight.