Cycling Gear

Fine tuning a new Thorn Audax Mk4 – living with tubeless tyres

I never really fell in love with my carbon fibre Cannondale Synapse road bike after a very scary speed wobble down a steep hill at 40mph. After much research and checking of spokes, head bearings and geometry, I couldn’t launch the bike with abandon down another hill. My Thorn Sherpa inspired confidence: rock-solid handling, fully loaded down the steepest of hills and ridiculous speeds, even on rough tracks. So the Cannondale, and an unused Brompton, were consigned to eBay to fund a new bike. I wanted something for long day rides and B&B or very light camping tours. After considering a Thorn Club Tour, I settled on a Thorn Audax Mk4. Together with my Sherpa, this would cover a broad spectrum, including all my intended cycling ambitions for years.

The bike was specified with Shimano 105 transmission, a Brookes saddle, carbon fork and TRP Spyre disc brakes – held together with lovely Hope hubs and a bottom bracket. Wheels are DT Swiss RR411 asymmetric rims which can take tubeless tyres. Lastly, the build included mudguards and a light rack, plus a T-bar for a front bar bag and an Alpkit frame bag. This is its light touring configuration.

With the glorious local weather and the pandemic lockdown curtailing any further adventures, I have stripped the bike for a summer exercise routine. The wheels came with tubeless Schwalbe G-One 30-622 tyres for winter use, that roll really well and grip like glue to slippery road surfaces. Now I use Schwalbe Pro-One tubeless, but fitting these has been a challenge.

On delivery, I discovered the tyres had been fitted with tubes, so after a few phone calls, Thorn sent me the tape, sealant and instructions for mounting tubeless. Their literature raved about the performance of tubeless tyres, run at lower pressures. Removing the G-One tyres, cleaning the rims and heating them gently with a hairdryer and applying two loops of rim tape, I added the tubeless valve. I fitted the tyre after pouting in 80ml of sealant. The tyre popped onto the rim with a reassuring click after an energetic use of a track pump. Gosh, I thought, these are easy to fit.

Come summer, I decided to fit the Pro-One tyres, as the G-One’s are not long-lasting and I wanted to start a regime of swapping the tyres each season, replacing the sealant. However, installing the tyres a second time around proved to be painful – I just could not get the tyres to inflate and ‘pop’ on to the rims.

Using inner tubes to keep me on the road, I ordered a Schwalbe air booster and some more tape. After much fiddling, I had to start from the beginning: spotlessly clean rims; new tape; carefully fitted valves and use of the new booster. It worked (eventually), and I can confirm that the results are tremendous – the difference in comfort and speed is noticeable. On the downside, the cost of tape (£25), booster (£45) and sealant (£30/litre) make this an expensive option. I hope the value of comfort and puncture protection (pinch flats and thorns) is worth it. I dare not consider a tubeless repair roadside, so I carry tyre levers, a cloth and an inner tube. It is a messy process but it will get me home.

This rigmarole is worth it. The bike handles brilliantly and is very comfortable – this comfort translates into performance, inspiring confidence and I find the bike is actually faster than the much lighter Cannondale frame (particularly down the long steep hills now :-). Imagine riding on a rough section of road that transitions to freshly laid smooth tarmac. It feels like smooth tarmac all day on tubeless.

So I am happy with the bike, now I have fettled the tyres and adjusted the geometry to perfection. The brakes could be a bit more powerful, but the Brooks saddle is slowly bedding in, and the bearings and gearing smoothing out.

Have I found love again? The Cannondale was a beautiful bike, but I prefer the integrity and function of the Thorn – a durable bike that will keep me happy for a lifetime.

3 comments

    1. Hi Nobby531,

      Firstly, the rim must be tubeless compatible, the DT Swiss RR411 has a hooked rim cross-section profile. I then made sure the rim was spotlessly clean, using window glass cleaner and a micro-fibre cloth and then heated the rim with a hairdryer. This is to make sure the rim tape seals better. I used 21mm wide Notubes Stands tape originally, but now use DT Swiss 19mm tape, wrapped twice around, overlapping the valve hole three times (so start the application 10cm beyond the hole. I also wrapped in the direction of travel. Make sure the tape is tensioned as you apply it. Of course, the tyres must be tubeless too!

      Secondly, I fitted the tubeless valve (I used Stans NoTubes 35mm Presta tubeless, which I prefer to the Schwalbe items). To do this, take a heated small cross head screwdriver (or similar) and melt a hole through from the outside, a small hole that will allow the valve to be pressed in and then screwed up firmly.

      Thirdly, I fitted the tyre in the usual manner, noting rotation direction. Make sure the bead sits either side of the valve and around the rim well evenly, trying to pull the bead to the outside where possible. A small application of tyre fitting gel helps, but I didn’t use this first time around.

      Fourth, pump the tyre up, using a track pump and booster (https://www.schwalbe.com/en/pressereader/handy-tire-booster-makes-tubeless-assembly-easier). I didn’t need the booster first time around, but it is essential I would say if the track pump doesn’t work. The tyre will eventually expand to fit the rim, with a loud pop (or two). I then pump it up to maximum (95 psi).

      Lastly, I deflate the tyre, removed the valve core, and then syringe in 80ml (3oz) of tyre sealant. I used Stans Notubes sealant. Replace the valve core and rotate the wheel in your hands like a wobbly dinner plate, to coat as much of the inside of the tyre with the sealant. Insert the valve core again, firmly but not overly tight and reinflate, with a booster. You then get some leaking, but keep pumping to maximum inflation and rotate the wheel again to make sure the sealant helps to bed the beads in and seal any leak around the valve. The tyre should now stay inflated. I leave it for a few hours and then deflate to low pressure (50 psi) and ride the bike around the block. Then I inflate to optimal (I used 70 front, 80psi rear, but experiment) and then go ride.

      I am not experienced with this, as a pro bike mechanic would be, but I am sure this procedure works. Try the many youtube videos too, especially the ones that focus on road tubeless. Larger sizes are much easier to fit apparently. I have had 1,000km trouble-free comfortable and fast riding trips now.

      Finally, when you replace the tyre (bad puncture or otherwise), the sealant is a bit messy but washes off with water and a big rag. I carry a spare inner tube as I do not consider it possible to repair roadside tubeless. Just removed the tubeless valve and refit as normal, no rim tape needed.

      Hope this helps. Ping me another note to say how you got on.

      Like

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