Lugging a Motor, Why it's Bad

DDBB said:
I did fiddle with cable tension with no joy. Visually the derailleur lines up with 8th gear. The bike has never been dropped or abused. I doubt the hangar is bent. Again, with the original chain, the bike has spent most of it's 2,000+miles in 8th gear. Although the teeth look just like all the others, I can't help but think I simply wore out 8th gear. I avoid 9th since it has so few teeth but now I'll be using it most of the time. Curious to see how long it will last. I don't start out in 9th and I don't mash the pedals either. I actually prefer 9th to 8th but thought I was doing a good thing by not using 9th. My other option is to reinstall the old chain that's at .5 or slightly more and simply ride it until skipping starts, then replace chain and cassette.
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Not cable tension... Derailleur adjustment.


And what do you mean by slipping?
Not staying in that gear?
Chain riding over the teeth?
 
Slaphappygamer said:
Does the new chain have as many links as the old chain? This is how I measured my new chain when I replaced the old one. I figure if the chain stretched, maybe the old chain would measure to a length in the middle of a link? IDK I’d that could happen. With this in mind, I just counted the links, twice, then removed the extra links on the new chain . Maybe the pros have a better method?
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stompandgo said:
I'm not a pro, but I don't count links. It all depends what I'm working on. For a wide range modern gearset, I hold the ends of the new chain together and pull them until the rear derailleur cage is tensioned properly, usually around 8 o'clock, then remove the closest outer link pin, leaving the two inner links for the master link. For older closer range gearsets, I do the same thing, but remove another one or two links so that when the bike is in the large-large combination, the rear derailleur cage is at 5 o'clock or so. Also, if the rear derailleur has a clutch, I turn it off for chain sizing and adjustments, and turn it on before it goes out the door.
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If the old chain was the correct length, I put it over a door and cut the new to the same length. Stretch is internal between the rollers and pins, not overall.

I make an old piece of spoke into a chain hook. It is about 75mm long with hooks on each end. That way you can size on the bike without fighting the tensioner.
 
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Gionnirocket said:
Not cable tension... Derailleur adjustment.


And what do you mean by slipping?
Not staying in that gear?
Chain riding over the teeth?
Click to expand...
Yep. Set the limits without the cable attached. Then set cable tension. Not indexing can be caused by cable friction, internal corrosion, or sometimes an over zealous cable zip tie on a shift housing. Also lube the derailleur pivot points.

REI hires big kids to assemble bikes. They will apply zip ties with plyers as hard as they can and it chokes the cable.
 
DDBB said:
,.. Visually the derailleur lines up with 8th gear. ,.. Again, with the original chain, the bike has spent most of it's 2,000+miles in 8th gear. Although the teeth look just like all the others, I can't help but think I simply wore out 8th gear.
Click to expand...

Try getting a close up picture with a good camera or cellphone.
You may be able to see some wear?

With 7th and 9th gear right beside it, you can reasonably compare the sprockets and their teeth.
 
DDBB said:
,.. Again, with the original chain, the bike has spent most of it's 2,000+miles in 8th gear.
,.. I can't help but think I simply wore out 8th gear.
Click to expand...

That's what I think is going on.
8th gear and your chain have worn out together and the spacing between your gear teeth has increased.

With the new chain, the chain is probably only pulling on the top tooth or two of 8th gear, but the chain contacts more than a few teeth around the rotation in every other gear so it stays snug.


20160812_140004chain-ncws-tall.jpg



DDBB said:
,.. My other option is to reinstall the old chain that's at .5 or slightly more and simply ride it until skipping starts, then replace chain and cassette.
Click to expand...

I think you should do exactly that, and save your new chain for the next cassette.
You might need to consider a chainring replacement at that time too?

I remember on my dirt bike, I had to replace the chain and both sprockets at the same time.
If I replaced just the chain, I'd stretch the chain in no time.
If I replaced just the sprockets, I'd wreck the sprockets just as fast.


Bicycle Chain and Sprocket Engagement and Wear

Maintenance of bicycle chains.
www.sheldonbrown.com
 
PedalUma said:
We had a birthday party by bike today riding all over and enjoying sights and treats. This little town just got ranked a one of the best to visit. I never heard of the Star Wars Collection. But they are right about the food.
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Self-reply, not generally good and very rare. We ate a giant cake made from freshly toasted pistachios, crushed and pressed, baked, then topped with thick dark melt-in-your mouth chocolate after a gravel section. That was after riding to another place that makes their own ice cream from local grazed cows, with espresso on top. There is an Italian name for that dish, I do not know the name, it is something like 'orgaismo oralae'. I am no good at Italian and don't know what that is or even how to order it right, except in common English. Put espresso on some fresh dark chocolate ice cream with dark cholate chunks. It can leave a person shaking knees in the air together for 5-25 times with the spasms of elation lasting .33 to 26 seconds. I do not know why.
 
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PedalUma said:
Perhaps the cassette calculation and calibration of chain length use even numbers on the high-end for a reason. I just had a 5:15 Saturday beer so I might not be fully cogent. Chains typically have narrow links and wide links alternating. A quick link only fits the outer plates = wide. But, and it is a big hot waxed Butt, half-link chains allow for refinement to an IGH of length to one link not two. They also have horizontal dropouts with limited room. You do not need to use an even number. So you could have a prime number of links, such as 113.
View attachment 196043
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Yeah I did a little reading and it's the ability to get a more exact chain legnth that is the 1/2 links designed benefit. Though generally beefier.. added strength is up for debate as the offset bent plates are weaker than straight. Rollers and pins aren't necessarily stronger and that all comes down to manufacture, same as with any chain. The real benefit is for BMX style bikes with limited tension adjustment in the rear dropout.
Interesting... but since I'm using a suspension rear with a tensioner and not having any issues with chain legnth or breaks.. I think I'll stick with what I have now.
 
DDBB said:
,.. with the original chain, the bike has spent most of it's 2,000+miles in 8th gear.
,.. I can't help but think I simply wore out 8th gear.
,.. simply ride it until skipping starts, then replace chain and cassette.
Click to expand...

I'm going to hazard a guess and say that when you reach .75 with your old chain, all the gears will start to skip and 8th gear will be the only one that doesn't ??

Although a worn chain on new sprockets (and all your gears except 8th are pretty much new), is probably different than a new chain on worn sprockets ?
 
I'm just going to leave the new chain on and avoid 8th gear for now. Maybe once this chain wears a little, 8th won't skip.. I actually prefer 9th but have avoided it to keep from wearing it out. If I wear out 9th then I'll just go with a new cassette and another new chain. I'm too lazy to put the old chain back on and it just doesn't seem right to do that. My high/low limits are perfect but I could mess with the B screw and see if I can get the chain to engage the gears a little earlier
 
Stefan Mikes said:
Rexlion, this is too low. A big part of the battery charge goes to the ambient as the heat because of low motor efficiency at such a cadence. Please try pedalling at least at 70. No harm to the motor if you pedal slower but pedalling faster will make your knees thank you. Just a gear down.
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I'd commented previously about my slow cadence, in the 50s. Well, after riding my mid drive for a while I found that it directly rewards a fast cadence, and it re-trained me. This is in contrast to my other ebike with rear hub motor, which does not improve performance with higher cadence but instead likes higher overall speed; the 750W rear hub motor (with torque sensor) therefore had taught me to be a leisurely cadence pedaler and to either use extra leg force or a higher power setting.
 
Rexlion said:
Well, after riding my mid drive for a while I found that it directly rewards a fast cadence, and it re-trained me. This is in contrast to my other ebike with rear hub motor, which does not improve performance with higher cadence but instead likes higher overall speed
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That's typical on the motor side of the equation. But like your mid-drive, you also have a convex-upward power vs. cadence curve. And its peak, per the book Bicycling Science, is generally just above your preferred or "self-selected" cadence — call it Cp.

My Cp's grown slowly without conscious effort over the years and now runs about 88 rpm — which happily seems to be near my mid-drive's preferred cadence as well.

Implication for climbing a hill that might bog your hub-drive down:

1. As you noted, hub-drives thrive on high wheel speed, so you need to keep ground speed up as best you can as you climb. Therefore, best to start the climb at the highest possible ground speed at a cadence above Cp.

2. Steady ground speed up a hill grows with total mechanical power Pt delivered to the rear wheel, and your pedaling contributes to Pt.

3. So best bet to keep a hub-drive from bogging down on a hill is to use the gears to climb at a cadence a little above Cp for as long as you can.

Seems to go according to theory on my own torque-sensing hub-drive.
 
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