OK, my story is this. I'm on a Trek 7.5 and do a 10km very hilly commute. I'm no speed merchant and travel slowly.

My Bontrager RaceLite HArdcase tyres were 28 wide, when they wore out I changed to Gator Hardshell 25's thinking that thinner would mean less effort to pedal. They are thinner and lighter.

However......they definitely seemed to take more effort and I was using higher gears for my journey.

I've done a lot of reading and it now seems that thinner tyres do not have less rolling resistance, just are more aerodynamic.

As a test I changed back to an old Bontrager Hardcase in a 32 from my shed and it actually felt less of a pedalling effort.

My questions are:

Is it true that for a slow, hilly ride, where all I am worried about is using the minimum effort (not speed) and all else being equal, a wider tyre would be less effort?

Is it likely that there is something in the character of the Gator which doesn't suit me?

Any other comments about a best tire width/type for someone who cares about minimising effort, not speed?

Or am I going mad??

The slower you are going and the harder the climb, the less difference the tires make. When you are struggling up a steep hill the overwhelming % of the work you are doing is propelling the weight of bicycle + rider to a greater elevation -- rolling resistance of the tires is almost completely immaterial. The only difference the tires will make is how much of a run you can get going downhill to carry you partly up the next hill. You have to be moving quite fast before aerodynamics of the tires are any more than a theoretical consideration, rolling resistance is more important.

Don in Austin

Tires definitely can affect speed. Lighter tires are faster. Tires with less rolling resistance are faster. And wider tires may be faster, as long as they don't increase weight a lot. Do you know what the weight difference is between your Bontrager and Gatorskins? If the Gators are wire bead, they might be heavier. Personally if I had to choose between two tires that weighed about the same but were different widths, I would take the wider tire. However, some tires are just slow because of high rolling resistance due to the rubber compounds they use and tread. I tried some Panaracer Pasela TGs for a while and had to get rid of them because they felt so slow. They were not that much heavier than the tires they replaced, but rolled so slow that they felt like they had glue on the treads.

No0 real advice for you, but I also have a 7.5 & went from the stock hardcases to a pair of continental gatorskins (not sure if that's the same tire you went with, but they sound similar) & had bad luck with them. In my case, it was more flats, but I ended up switching back to the stock tires & am much happier.

Mine were actually the Gator Hardshell. But I'm thinking about the gatorskin - apart from the fact, given that they are lighter than the Bontragers, did they feel any different? What size are you running?

Gators are about 80g lighter I believe, so its odd. I wonder if stiffness of rubber/sidewall could make such a difference?

Cheers DOn. What about momentum of a heavier tyre? Any help?

You'd likely be most happy with a bit wider tire, and if the budget allows, a tire with a folding bead as they are lighter than wire bead tires.

Rotational weight is comparatively your worst enemy on a bicyle both for climbing and acceleration purposes which is why racers invest heavily in carbon fiber wheels and very light skinny tires. As for rolling resistance, generally speaking a tire that deflects and/or bounces less is going to be a nicer rolling tire. A wide volume tire rolls over imperfections on road surfaces, a skinny hard tire will bounce and deflect, which will require more effort to propel forward.

If your frame can fit them, 32-35 mm tire width hits the sweet spot, IMO between comfort and efficiency. Folding bead definitely helps with rotational weight (lower inertia).
A larger tire casing will provide better comfort and more secure handling than a skinny tire, without sacrificing much in the way of rolling resistance.

The rest of the formula is your own fitness. As your fitness level improves, you'll find that the hills aren't so bad, after all.

I have lately found Conti Sport Contact tires. They seem to be as fast as any fat tire I have ever used. They come in 28, 32 and 37. At my weight I like 37, but you might want to consider 32.