keraba2

I have 3 bikes with Shimano IGHs: a 3 speed in an Italian road bike, a 7 speed in a steel commuter and an 11 speed in a carbon racing bike. This post is to describe how the latter 2 compare in performance. I made this comparison because I've read over and over that things like bike weight and tire width doesn't matter, and that IGHs have a negligible cost. This test will show that there's a huge difference /between/ IGHs!


This will be a short, amateurish comparison. I don't have a bike treadmill and power meter pedals. All I have is the hill in my neighborhood, and a Fitbit.


With that, here's some data:





In each case, I descend the hill and then ride back. I attempt to exert myself the same amount each climb.


The first descent is on the 7 speed. It hits a peak of 15mph. Climbing back, it hits a peak of 10.33mph with a consistent heart rate of 150. I /think/ the wheel size that I climbed with was 48.8".


The second descent is on the 11 speed. It hits a peak of 17.9mph, a significant difference. Climbing back, it hits 12.2mph, again, a significant difference, and interestingly my heart rate goes from 150 to 130! Not sure if this is a Fitbit mistake. I /think/ the wheel size that I climbed with was 58".


My conclusions: First, the 11 speed (and its bike) somehow has a much lower resistance just coasting (downhill). Maybe this is due to the 11 speed having oil lubrication while the 7 speed is grease, but the racing bike's skinny wheels (1" vs 1.5") could also be contributing. (I made sure the 1.5" wheels were pumped up hard.)


Second, between the resistance of the 7 speed and its weight (30# vs 21#), it has a /much/ higher effort to propel it uphill. The 11 speed has such a low effort to propel uphill that I could use a larger wheel. I don't plan on listening any more when people say that things like weight and tire width don't matter (much). These are 20% differences, and they compound each other!


Anyways, enjoy.

koala logs

That's a very huge wheel size!

ClydeClydeson

Good effort, but meaningless. Using two completely different bikes means you can't know if the speed difference was because of the IGHs or because of some other factor (bike weight, tire rolling resistance, chain drag, aerodynamic differences from different rider positions, etc). Your conclusion that different IGHs are different in performance is not unlikely, but you have certainly not proved it. The difference in coasting speed is a clue - the gear mechanism of an IGH is not activated by coasting, so you are only rolling on the outer bearings like in any other hub, so the difference in coasting speed is almost definitely due to other causes. Whatever drag was causing the 7sp bike to be slower that is not in the IGH will also cause it to be slower when pedalling.

base2 

^^^

Agreed. What he said.

All IGH's have some cost. But, so do all the other types & styles of drivetrain as well. I've never known any of my IGH's to make a meaningful difference over my conventional derailleur drivetrains. Well, any difference I could locate specifically to the hub once properly broken in. There is just too many variables to account.

It's not like any difference between bikes couldn't be made up elsewhere. Like switching to tubeless, getting good tires, or (gasp!) doing both, for example.

Oil bathed IGH's seem to do best, IMO. It's not hard to squirt in a bunch of Phil's Tenacious & hold it in the hub by packing the cap with marine grease. But, I don't know that this isn't simply placebo effect either since I do all my own maintenance.

My Nexus 7 Dahon "feels" slowest of all. But it's on a 20 inch folder, with Marathon tires, driven by a Schlumpf drive in overdrive most times. My Pugeot with the same hub & Rene Herse 26x1.75 tires is a completely different experience than that of the Dahon. It offers every bit same experience as any drop bar bike "should" give. Apples to apples: It's not the hub. It's the bike.

Maybe my experience suffers from sample bias. Who knows?

Good luck learning the in's & outs of the scientific method.

keraba2

"you have certainly not proved it"

I didn't claim that I did, troll.

"the gear mechanism of an IGH is not activated by coasting"

A dragging clutch, particularly soaked in grease, would absolutely cause this.

base2 

Oh, ok.
That's how this thread is going to be.

OldTryGuy

My 7spd rides like I'm going uphill in both directions. I've also read comments that the 7spd is INDEED the worse hub

Rick

I purchased a Belt driven Rohloff equipped bicycle in 2013. I recently purchased a belt drive ebike with a Enviolo IGH to pull my Carla Cargo Trailer. I have read and commented about added friction but really am not concerned about it. I like my belt drive bicycles and am not interested in chain driven bicycles anymore.

ClydeClydeson

People with any amount of self awareness would be trying to improve themselves. It must be nice not having that burden.