tatfiend 

I got curious about what the theoretical weight difference would be between a typical IGH system and my Big Dummy's triple derailleur system.

Using the internet I added up the weights of all the parts that would be removed in such a conversion. They came to 1437 grams and did not include the weight loss from the removal of the front derailleur cable or the shortened chain usually used with an IGH. For the derailleur shifters weight I had to substitute Shimano's listed weight for their XTR shifters as I could not find the weight of the SLX shifters used on the BD.

The Alfine hub weighs 1680 grams supposedly so the weight differential is 243 grams. To this add the weight of the IGH shifter and possibly the weight of the casette joint and rear sprocket. The weight differential between the two drivetrains is still going to be under a pound for this particular case. IMO this is a minor weight change for the type of bikes likely to be converted to IGH.

When people pick up a IGH bike I suspect what they are noticing is that the weight is all concentrated in the rear wheel which may make the IGH system bike feel heavier. The weight removed in this area though by the change totaled almost exactly 1000 grams for original rear hub, cassette and rear derailleur. That makes the rear end weight increase about 680 grams.

bigvegan

Thanks for doing the math. I always wondered how light an IGH bike could be, as the 47lb dutch city bikes didn't really do it for me.

That sounds pretty reasonable.

SlimAgainSoon

What was the total weight of each system?

A friend of mine and I were trying to sort this out in our heads just yesterday.

noglider 

I didn't realize the weights are that close.

Mind you, the IGH generally uses a wider chain, which will add weight. Did you account for that?

Also, the IGH presents a bit more friction. Not a big deal for most of us, but still, it should be factored into decisions.

One of these days, I'll build a bike for myself with a 5- or more-speed hub, mostly for fun.

tatfiend 

Hard to find weight figures on some components and things like crank sets can usually be used with either system. I figured the weight of the two removed chain rings at about 80 grams. The IGH shifter will vary a lot as typical twist grip IGH shifters are a lot lighter than the Alfine dual trigger shifter, if used. Sorry but I am not going to disassemble my Alfine rear wheel to weigh the hub with cassette joint and sprocket. The Jtek shifter I am using with the Alfine is IMO about 40 grams or less.

This is just a ballpark calculation for replacing a MTB style derailleur system with an IGH, in this case the Alfine hub.

tatfiend 

Shimano and SRAM Hubs come with sprockets designed for 8 speed chain and the Rohloff hub sprocket will work with 8 or 9 speed chain per Rohloff so I did not factor in greater chain weight for the IGH. Very possibly a wash as unless using a chain tensioner the IGH drive chain will be shorter than the one for a derailleur drive.

The few studies I have seen of IGH versus derailleur drive efficiency have used new IGH units. I would expect efficiency to increase slightly as the IGH broke in. Rohloff claims that is true for their oil lubricated unit.

Per a study published in the IHPVA Journal some years ago it is surprising how low the efficiency of a derailleur system was when using the smallest rear sprockets, a 12 tooth minimum one in their test. Overall IGHs averaged about 2 to 3% less efficient than derailleur gear trains at moderate power levels. Very little actual test data has been published for either type of drivetrain unfortunately.

noglider 

Also, a derailleur system is more prone to grit and grime, which reduce efficiency.

AdamDZ

I find that if I wipe my chain, RD, chainrings and casette quickly after each messy commute (rain, snow, sludge) they don't accumulate much grime and remain smooth. I carry a brush with me and give them a quick clean if needed, it takes a minute. Then a few drops of light oil every few days. Sand would probably be a whole different story though. I had one bad experience with an IGH and I'd rather have regular derailleur drivetrain that I can take apart and clean and overhaul if necessary on my own.

Adam

tatfiend 

AdamDZ;

I am not necessarily recommending a IGH to anyone, though I like them personally. In this case I am just trying to set the record straight as to the comparative weights of the two systems for comparison purposes as I keep seeing unquantified comments on how heavy an IGH system is compared to a derailleur system.

I have seen a fair number of busted up derailleurs too and several members of the IGH group linked to in my signature block shifted to IGH drivetrains as a result of multiple derailleur drivetrain failures. I ride both and believe that each has it's place in the scheme of bicycle design and use.

Unless replacing a ultra light road derailleur system with a fairly large and heavy IGH I suspect that the difference in weights will almost always be in the neighborhood of a pound or so. This does presume the use of a freewheel type IGH rather than a heavier coaster brake or drum brake unit.

It is easy enough for anyone to look up weights, or weigh, their own particular parts and make a determination of the approximate weight differential. I was merely trying to point out that when figuring the weight of an IGH conversion you need to account for both weight removed as well as that added by such a conversion. The average freehub and cassette or hub and freewheel, as well as derailleurs, are not weightless.

LarDasse74

My main bike right now has an Alfine hub with a chain tensioner, but using a standard 8 sp. chain. I don't make it a habit to weigh my bikes or parts, but the bike doesn't feel much heavier than it did before the conversion... the weight is a little more concentrated in the rear no, though.

I went with an IGH because the weight penalty would have to be massive for it to make a difference for me (I weigh 270 lbs) and because I have had derailleurs snapped or ripped off my bike several times, and IGH drivetrains are sealed and are lower maintenance.

Elkhound

Three of my four bikes have internal hub gears, and the fourth will be converted soon.

AdamDZ

Oh, I wasn't arguing your points or anything, it was more of a loosely related response to noglider's comment on efficiency. In any case, I really don't think that the type of cyclist who is seriously considering an IGH would care that much about slight differences in weight and efficiency. IGHs are not for performance oriented people but more for commuters and tourers and they already carry lots of extra pounds - or kilograms

I actually liked the way the 4-speed Shimano IGH I had worked but I was disappointed that it lasted less than 2 years, got grit inside and just stopped working and you can't really take this thing apart unless you're a mechanical genius. I wanted more gears and I was reluctant to spend $$$ on 8 or more speed IGH.

Adam

noglider 

Has anyone taken apart a modern IGH? I'd like a comparison of servicing them with servicing the old Sturmey Archer AW. I consider the AW to be easy to service. Not only that, service is necessary on those hubs rarely.

One thing I did notice in the 70's is that the combo coaster brake/IGH hubs needed service more often than plain IGH or plain coaster brake hubs. I don't know if that's still true, though I would expect it to be.

cman

The modern Shimano's seem to be okay. Here is a vid of a Nexus 3speed coaster brake.
https://s202.photobucket.com/albums/aa206/puretexan2/?action=view&current=00000012.flv

noglider 

Thanks, cman. Easy enough, though that's a 3-speed. I'll bet there's little difference among all the various 3-speed designs, old and new.

That brake looks underdesigned. I think I'll stay away from the combo gear/brake hubs.

jsharvey1961

RE; Noglider

I purchased a used Shimano Nexus 7R40 internal hub a while back and after installing it determined it really needed to be taken apart, cleaned, and re-lubed. I had never taken any internal gear hub apart, but it was very easy to do so - it was also easy to put back together. It now works flawlessly. There are just several component pieces that had to be solvent cleaned and then put back together in the correct order and orientation.

fietsbob

I Have found the Drum brake hub Sturmey Archer makes, to work quite well .

Big Dummy puts a lot of cable between the lever and the hub, so I'd use beefy cable and housing,
and a V brake 4 finger lever..

Though disc mounts being there, on the frame,

A hydraulic disc is better, due to the line length..
Magura has a hydraulic rim brake, they are the best rim brake I've tried..

can probably get away with a mechanical disc up front..

interested

Shimano has some excellent info on IGH's in their rather unknown "Tech Tips" section of their web-site:
https://bike.shimano.com/publish/cont...tech_tips.html

Here is the service manual for the Nexus 8 IGH:
https://bike.shimano.com/publish/cont...08%20ohaul.pdf

There are many steps and many places that it can go wrong, and the above pdf only describes a re-greasing overhaul, not an entire disassembly. Easy servicing of this hub didn't seem to be a major concern when it was designed. IMHO, it is much more cost effective to flush it in ATF oil or Shimano's IGH oil instead of re-greasing it, even if it means a lower service interval when converting it to oil.

Regarding coaster/IGH combos requiring more service, then I suspect this is still the case. The added torque and deformation of the hub shell when braking probably adds something to the wear and tear.

--
Regards

interested

There are many ways to compare derailleur systems and IGH's. Eg. take an Alfine S501 8 speed IGH versus a 1x10 speed derailleur system. The latter have more gears but probably less total gear range. Still a 11-28 cassette or even a 11-34 has a reasonable gear range. Assuming that a Shimano trigger shifter weighs roughly the same whether it is for IGH's or derailleur systems, everything else will be roughly equal.

IGH: Alfine: 1680 g. (with fittings but without rear sprocket?)
Derailleur:
Shimano 105 (5700) rear hub: 353 g. (without QR)
Shimano 105 (5700) cassette 245 g. (11-25)
Shimano 105 (5700) derailleur 221 g.
Total: 819 g.
A difference of 861 g.
Shimano 105 isn't very light either. By using Shimano Ultegra and finding a lighter hub it is easy to shave another 150 g. of that setup, making the the difference more than 1000 g./1 kilo/two pounds.

Even adding a front derailleur (120 g. for a Shimano 105 ) and a 52T chainring etc. won't eat much into that difference, while providing more gear range and gears.

While particular conversions may result in a low difference because the bike had heavy parts to begin with, it is reasonable to expect a 600-1000 g., minimum weight difference between a modern Shimano Alfine 8 IGH bike and a modern Shimano 105/Ultegra equipped bike.

--
Regards

bikemeister

To counteract a 1000 gram increase, just leave one water bottle off your bike. Total weight is now the same. Problem solved.

tcs

SRAM S7 disassembled AND reassembled in two minutes and 32 seconds
SRAM S7 disassembled AND reassembed in under 7 minutes BLINDFOLDED.

(BTW - not by me!)

Kimmo 

o_o

spectastic

AnkleWork

It only took you four years to add that enormous content?

spectastic

I was busy finding the perfect comment