mattscq

So I have a road bike which has pretty decent tire clearance (somewhere between 32-35mm) so I decided to get a pair of Gravelking SK+es on them to try a little (petite) off-road. I get the 32mm TLC versions but threw some Schwalbe tubes in them (not quite ready to leap to the tubeless train yet but my rims and tires are ready) and I pump them to around 60-70ish PSI and off I go.

The ride is definitely way plusher than what I had before (25mm Grand Prix 4000 IIs at around 90-100 PSI) and I am surprised at how much more I'm able to do now (whereas I used to be terrified if there was as much as a few pebbles on the tarmac). One thing I have noticed though is a lot of "drag". Acceleration is much slower and I feel like I need to put down a lot more power just to go the same speed I used to on the same surfaces. While my off-roading is great, my on-roading is much more sluggish. Same bike, same everything, except different tires. Usually I would think it's all marginal gains and I'm only saving a few watts but it feels like I'm putting down 15-25% more (maybe even more) just to go the same speed on tarmac.

I know I'm comparing a fat knobby tire to a racing tire but is this normal? Would I have been better served with the non SK version? This isn't really a huge issue but I'm mostly just curious if I set it up wrong or this is perfectly normal.

fishboat

Maybe try them with a little more air. I've ridden the SKs on road and they seemed to roll very well. Sounds like you might be able to get away with the Gravelking slicks. I ride these on most of my road bikes..very nice tire. The plush ride of larger, easy rolling tires is addicting.

Marcus_Ti

SKs are a good small knobbie tire which does a little of everything...they're not a fast tire though--and are not that supple. IMHO.

unterhausen

60-70 should be enough pressure for that tire. It's a lot more tread than your old tires, so maybe there is more drag. But I think the feeling of sluggishness is from the reduced road feel.

DrIsotope

First the disclaimer that the OP's butt dyno might need re-calibrating, just because a tire feels slower doesn't necessarily mean it is.

At the same time, there might be something to it, as the SK+ is ~40g per tire heavier than the "plain" SK, which isn't a dealbreaker, but all of that weight is the additional puncture resistant belting. I only have experience with the SK, which I didn't notice to be particularly draggy, at least for what it is. I have ridden both the Panaracer Pasela and the Pasela Pro-Tite, and the Pro-Tite (with that extra protection belt) did feel... clunkier.

So in the realm of internet guessing, the SK+ is probably a bit slower than what the OP is used to, but probably not as slow as he's guessing.

mattscq

I guess I could do a test and hold a certain power and see how fast I go over the same piece of tarmac. I'll try that sometime and report back. What I am thrown off by isn't the actual speed (I don't stare at my computer the whole time I'm riding) but just the sense that it feels like I'm pushing much harder to feel I'm going the speed I want to be going.

Gconan

The tread has more rolling resistance than non treaded tires.

Gconan

Bicycle rolling resistance

fishboat

Good points..and a correction to my post above..I glossed over the + behind the SK..my error. I've never ridden the SK+, only the SK..which I thought felt fairly (surprisingly) close to the GK slick.

It isn't unusual for the more puncture-resistant versions of some tires to be real slugs on the road, due to added weight and a stiffer overall composition(more rolling resistance). I believe that's the case with the Schwalbe Marathons..from what I've read.

mattscq

So according to BRR, I'm getting about 10-11W more rolling resistance and the tires are about 200g heavier. Definitely not nothing but enough to feel that noticeable? I suppose adding 10-20W to my pedaling IS noticeable.

fourfa

BRR figures suggest 21.7W for the GKSK (the GKSK+ should be worse yet) vs 12.9W for the GP4000sII. (standard disclaimer here about drum tests, please save your breath)

If you're only looking to try 'petite' off-road, I strongly suggest trying out the GP5000TL 32mm (and a pump). Set them up tubeless. There's a good chance these will roll *better* than your GP4Ks on pavement, and more comfortable as well. They're 375g to the GKSK+ 360 GKSK 320g.

Deflate somewhat off-pavement, and they'll stick to the trail in a way that will probably surprise you. Tread knobs in many cases don't matter, when the low pressure tire can just wrap around the road. This is where tubeless setup rules - you can deflate to where you're not quite hitting the rim when you bounce on it, which would ruin your day with pinch flats using tubes.

This is why I mention the pump - frequent inflation will show you if your mini pump is really just for emergencies. MTB pumps are usually set up for high volume but low pressure - you want something that will reach back up to the road pressure you want. CO2 isn't totally out of the question but IMHO the cost will discourage many people from actually adjusting their pressure as often as they should.

Regarding TL setup, you likely don't require any new equipment like fancy dual chamber floor pump, compressor, bead jack etc. Just inflate with a tube to seat both sides, deflate and remove one side (careful to leave the other side seated), remove the tube, and inflate. This has always worked for me. However there are some rims that just won't work this easily, hopefully you don't have one of those. Maybe share your rim type?

Rides4Beer

Going from a 25mm fast road tire to a bigger gravel tire will defintely add resistance, but the Plus version of the SK is significantly slower than other gravel tires, I noticed it instantly when I had a set. Unless you need the extra puncture protection, I would go for a more supple gravel tire that still has decent puncture resistance.

unterhausen

I have found the SK to be fairly puncture resistant. I suppose because of the knobs. I have ridden them on 100km rides on the road, and don't think they are particularly draggy. The + in SK+ involves things that would suggest higher drag, which in this case seems unnecessary

HTupolev

Protection layers tend to increase rolling resistance. Very tough layers tend to create very large increases in rolling resistance.

I haven't been around the "plus" gravelking casing, but it wouldn't surprise me if Panaracer has chosen to not take half-measures here. They've certainly made tires in the past that are extremely tough and also extremely slow. And "plus" is sort of a tire-industry code word for "rolls like a sack of potatoes."

guadzilla

If you look at BicycleRollingResistance, you can see a 10-12W difference in rolling resistance just for various road tires, compared to the fastest tire. It wouldnt surprise me if your SKs are atleast 10-15W slower than your GP4ks. So yeah, to be expected.

chas58

Its a huge difference for me, but it depends on how you ride. But that is per tire, so (24.7-12.2)*2 = 25 watts (at 18mph). That is about 10% for someone in good shape cruising along. The "+" may add 5+watts drag for a pair of tires (so 30 watts?). I do cruise about 10-15% faster on the Conti's

I did the happy dance when they came out with the 32mm version (GP5000). It made a huge difference for me drafting at high speed (25-30mph)
(24.7-8.3)*2*1.5 = 50 watts savings. That is something I can feel - its the difference from being dropped vs being at the front of the pack.

32mm for me is a great summer/fall gravel tire around here.

autonomy

FWIW, I changed 40mm Xplor MSOs at 80PSI to 50mm GK SK+ at 50PSI (on the road) on my steel adventure bike and I noticed 'sluggishness' as well, but Strava says I've had no trouble beating records I've set on this same bike on the MSOs OR getting close to records set on my road bike with 100PSI 28mm tires, even on minor climbs, so go figure.
Did a loaded daytour with my wife and had little trouble keeping up with her carbon bike. Granted, I'm a stronger cyclist than she is, so not a fair comparison. She later complained about being beaten up by the rough pavement, meanwhile I thought "huh, the pavement was rough?". I may have spent more energy pushing the heavier, possibly sluggish tires, but at the same time I feel like the plushiness made up for that.

mattscq

That is interesting—using GP5000s on gravel. I suppose before I knew any better, I got lost in a park once and ended up on some paths that seemed like nobody had travelled on or serviced in decades (so broken up it was basically loose gravel) and I managed to get by on 25mm GP4000s at probably 80-100 psi. It was crazy bumpy and not pleasant but I didn't flat and continued to ride many many miles after.

I do realize now that the knobby SK+ were probably designed for very loose gravel and mud which I don't really encounter that much. If I wanted a slightly better all-rounder, would the slicks serve me better?

tyrion

Slicks do not have the traction of those SKs, except on clean pavement. I recently switched from Gravelkink SKs to some slicks (Soma Supple Vitesse) and the slicks are great on clean pavement but if there's dirt or sand on the pavement they lose traction much more than SKs. I would characterize the SKs as the "all-rounder", but they are slower.

dwmckee

The GKings are a pretty fast tire but you are comparing them to one of the very fast road tires keep in mind. That is, fast at a constant speed, but acceleration will be a bit slower due to the extra tire weight on the GKs compared to the GPs. Two other great fast and wide tires I love that are somewhat lighter are the Challenge Strada Biancas and the Rene Herse extra lights. Bioth are outstanding. I am riding Rene Hrse right now on my Open actually.

chas58

Yeah, if you don't encounter a lot of loose gravel and mud, that is an option. Jan Heine (Bicycle quarterly, Rene Herse tires) wrote an interesting article on how slicks and treaded tires have basically the same traction in those conditions (for what that is worth).

I chose the 32mm GP5000 if I'm riding on gravel less than 2cm in size, when 40-45psi is enough, and when it is dry (pretty much everything this type of year). They are best for mixed road/gravel, because they roll very very nice on the road. If its muddy, sandy, rocky, rooty, or more of an edurance ride (where I want lower psi), something bigger is my choice. A lot of it is my bike, but I ride some pretty nasty washboarded stuff on these, and its shockingly smooth. But if you need a bigger slick, the slick GK, or Rene Herse have some good options.