Or put a better way: are they more efficient?
While the Tero was at the menders I took my 2022 Merida Big Trail 500 on a 20km ride. Halfway through I started wondering: why I got an e-bike at all? The 15-kilo HT was effortless to manage and nippy to accelerate on its skinny Conti Double Fighter tyres. But the fact that the route clocked up only 120m of gain must have a lot to do with it. We climbed seven times that e-biking only twice as far in Purbeck the previous weekend. That would not have been a doddle on the Merida.
Next day I was down in Devon with a mate, my Merida and his dinky custom e-Brompton loaded with overnight packrafts (above). Our 36-km backroad route to the coast had an elevation profile like something off on the Richter scale but again, I was amazed how effortlessly the Merida managed the rarely level backcountry lanes. Any fitness I’d gained from the recent Wales trip had surely worn off, so it must be down to the efficiency of the Merida’s drivetrain which has always struck me as uncanny – and helped again by the smooth, 2.0 Conti DF tyres.
Retyring the Tero X5
It got me thinking about retyring my Tero X5 which had always my plan. For what I do off road – which isn’t something out of some MTB pop video – I don’t need knobblies, even if they look purposeful. But Double Fighters 29-ers (above right) only go to 50-622mm – just over 2 inches actual width – which I thought might be a bit narrow on the twice as heavy Tero, while being a bit skimpy on the shoulder lugs when loose dirt cornering or climbing out of ruts (the only time I find knobblies useful). I wanted something in between but erring closer to the DFs and with the same killer puncture protection.
After hours of bouncing around the internet I settled on some Schwalbe Johnny Watts LRs in 2.35. On our Himalayan rides years ago, Schwalbe Marathons were the flat-proof touring tyre de jour. The Johnies are definitely knobblier than the old Conti DFs, but highly rated on rolling and protection, and smoother down the middle. They cost from £32 and £40 for the E50 Long Ranger version (above right) which is intended for pedelecs which go over 25kph so a bit OTT. The Contis can be as little as £23.
The front 29″ LR weighs 1066g and the rear 27.5″ 985g (Schwalbe claim 1010g/950g). The OE 2.35 Specialized Ground Control T7s they were replacing weigh 860g and 822g after 1000km of wear which must have flattened the profile, creating yet more road drag. Even then, what I might gain from the Schwalbe’s’ reduced rolling resistance I could lose spinning a heavier rolling mass. But as with the Merida’s Conti DFs (915g in 29″), I’ll happily take a bit more rolling mass for added puncture resistance. In the four years they’ve been on the Merida I’ve never had a flat – and that’s without Slime.
Comparing tyre rolling resistance
I see these days they rate bike efficiency (rolling resistance, drivetrain drag and aero) in watts, and the X5’s TDC display has a live watt read-out, whether in Assist or on Standby. In fact it’s the display’s calorie reading which accumulates over time and distance, so it should be possible to compare the Ground Control’s calorie draw against the new Johnnies over the same distance. It took some effort to make sense of the MasterMind TCD’s power screen. You can read about that here.
Another way of comparing rolling resistance is simply coasting down a hill and comparing times. Or, without a stopwatch, roll down a dip and see how far you get up the other side. Of course it’s not truly fair comparing a worn pair of knobblies with a brand new tyre but we’re here so let’s get on with it.
Ground Control to Major Watts
With a strong WNW evening breeze blowing, the geef and I set out on an 18km loop with a 99m gain according to the OS app (graph below). The TCD displays elevation gain too but I’ve found varies wildly over the same ride. The lap was about 35% trail; I rode in Standby to get a pure unassisted reading. The pace with the geef is a bit slower.
Specialized Ground Control T7 2.35 (1050km old)
Fr 860g, Rr 822g • 30psi
Combined tyres & Slime rear tube 2346g
The loop took us 57 mins with a couple of minutes faffing and I drew 521 calories. I was down to 1st on a couple of short climbs, but hit 37kph on the home flat with a nice backwind, a bit more than my usual top speed along this road on these tyres.
That done, I dropped the dropper, crouched down and let the bike roll down a nearby backroad for 850m with a 23m drop. With no braking that took me 2:03 with a 30kph top speed and of course used zero calories.
That evening I mounted the Johnnies. After years of doing motorbike and even 4×4 tyres, I can’t get over how easy changing bike tyres is. Just one lever and two hands gets them on with little risk of maddening tube pinching. Removing the rear Ground Control, the tube hissed and Slime pooled in the tyre. Sure enough, a thorn had come through the thin carcass as with many knobblies I’ve tried, but with Slime, the tube pushing against the inside of the tyre had kept things airtight (I’d just verified it was 30psi). I’m shocked how flimsy these Ground Controls and indeed all knobblies feel compared to the Schwalbe JW’s which are 20% heavier.
Once aired up, the Johnnies looked just what I’d hoped for (above), a tad less wide than the knobblies, but wider than the Contis and with the same pronounced crown making a narrow road rolling contact. before it got too hot we set out on the lap again, me hopefully to burn up fewer calories.
Straight away on the road I noticed the bike rolled smoother and the tyres were quieter, but it didn’t feel nippier; I’m pushing 28 kilos after all. Even on the trails I got the impression the bike rolled with less effort. The LRs felt a lot like the Contis.
Schwalbe Johnny Watts LR 2.35, new
Fr 1066g Rr 985g • 30psi
Combined tyres & tubes 2741g
The Schwalbe lap took 54 mins (not really relevant) and consumed… 478 calories – a reduction of 9%. Notably, I never needed 1st on the climbs, and on the rolling home flat with no wind again hit 37kph but only momentarily. The 850m downhill roll took 1:56 with a top speed of 32kph: that’s 4.9% quicker.
So the test shows that over 20 odd kms and despite an overall 17% weight gain in the critical rolling mass, Long Rangers burned noticeably fewer calories which ought to translate to better range as well as more miles easily pedalled in Standby. It’s certainly feels that way.
Test completed, time to tuck into a wholesome brekkie!
A couple of days later the geef got another thorn flat in her Lapierre. The tubeless-ready rims on that bike make removing a tyre without a vice and wood blocks near impossible, so I’d added Slime which clearly did not work.
A 1000 miles in it was time to ditch the OE WSB Ranger knobblies and fit some Conti Double Fighters I go on about above. At half my weight, the DFs ought to handle her overall mass OK. We went out for a ride.
‘How are the new tyres?’
‘What about them. Are they new?’
‘Never mind…’
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