Chain skipping 9th gear rear hub motor

[creativepart]

I have a Specialized Crosstrail hybrid that I built with a Dillenger Premium OffRoad rear hub drive kit.

The bike came with a 2x9 groupset and this included a 9-sp cassette. The kit wheel required a freewheel so I ordered one of those from Dillenger, too. The derailleur and all else is original.

All works great EXCEPT 9th gear. It skips under even lite load. 8th gear works great so that’s what I use mostly. All the gears index correctly and on a stand 9th gear runs fine. It’s just on the ground and it’s skip, skip, skip. Like it’s skipping teeth.

I’ve tried many things. Mostly diy and some with a bike shop tech.

Tested the hanger, put on a new 9-sp chain, adjusted the limit screws again and again.

I tried to put on a different freewheel but it contacted the hub motor and wouldn’t spin.

The bike has 135mm width dropouts and the 9-sp freewheel is a bit taller than the original cassette. Maybe 6mm or so taller.

I’d like to figure this out myself but will resort to a bike shop if need be.

I’m wondering about chain line due to the taller freewheel?? Also wondering if a 7-sp freewheel would be a fix?

Any ideas would be appreciated.

 

[2old]

The chain seems pretty close to the frame and maybe with your weight on the bike contacts it. If I were you I would try spacing out
the hub a mm or so (one of those "half washers they use on the front forks to accommodate "lawyer Lips"), and try it. Going to an eight speed probably would solve the problem too , but you would need a new shifter IMO, and seven is the same width as eight except you use a spacer for the one less gear.

 

[creativepart]

Thanks, I’ll give that a try. The kit actually has two of those washers that I did not use in the build.

I’ll report back.

 

[motomech]

We don't know what brand the freewheel is, Dillenger calls it their preferred "genaric" brand , but it would help to know.
The Enoch DNP, the most commonly used ebike freewheel, due to it's "shark fin" shaped teeth, often requires some derailleur adjustment to prevent skipping. Basicly, the wheel of the derailleur needs to go down and further under the freewheel.
The other things to consider are, is your chain width. If it's a super narrow chain, the freewheel teeth may too wide for the chain to fully seat and it shows up on the 9th gear because it receives more "torque".
The other is, does the freewheel have an 11 T sm. sprocket? If not, it's not going to be that useful for an Ebike, where one wants as much top speed gearing to be able to pedal along at ebike speeds.
For the longest time, only the heavy and clunky DNP would provide the desired 11T gear, so we "bit the bullet" and went w/ it.
I believe Sun Race (or maybe Sun Tour) offers one now, but I haven't used it.

 

[creativepart]

Actually, i expected it to be "generic" or DNP but it says Sunrace on the end cap.

I didn't notice the Sunrace on it when I installed it and I thought it might be a problem with the freewheel. So, I bought a replacement Sunrace on Amazon. The two looked quite a bit different. The one from Dillenger had a dished back with a deep thread well. The replacement was much flatter and even had a round section that stood proud of the gears. When tightened it would contact the motor hub and not spin. I tried different washers behind it and it took 3mm of washers to spin when tightened but then it just made everything further out of line and was a bear to get into the dropouts. So, I returned the Amazon freewheel and reinstalled the one from Dillenger.

I believe the freewheel is 11T - 32T. That's what it's supposed to be. I haven't counted the teeth.

 

[motomech]

For some reason, I didn't see the pic during my first look. It doesn't look like a narrow chain.
If you are still experiencing skipping, you might try adjusting the derailleur, it won't cost anything.
The idea is, you want to get the chain further wrapped the gear whl., that's why you want to move the derail. wheel more under the gear-set. On a DNP I had that skipped on top gear, the derail. ended up quite close to the gear-set.
Although not physically difficult, it's a little confusing as to what screw does what at first.
Plenty of info on the net about adjusting the derail., Sheldon Brown might be a good place to start.

 

[TommyCat]

The idea is, you want to get the chain further wrapped the gear whl., that's why you want to move the derail. wheel more under the gear-set.

+1 This worked for me with a 7 gear free wheel slipping on the highest gear.

See how the adjustments were made in POST #36 as seen here...

https://electricbike.com/forum/foru...t-52v-11-5ah-huffy-parkside?p=61787#post61787

With a complete discussion about it here...

https://electricbike.com/forum/foru...0729-pop-slippage-in-chain-drive-train-solved


Regards,
T.C.

 

[markz]

I like your torque arm, is that custom or bought?

.

 

[fechter]

Anything that increases the chain tension will help a lot too. Some derailleurs have an adjustment for this.

 

[amberwolf]

One further issue that can happen is if there is too much chain for the derailer to wrap and keep tight in the smaller gears. A longer derailer (more distance between the pulleys) can deal with a greater difference between the highest gear and the lowest. Or, as long as it doesn't make the largest gears you need to use pull teh chain too tight, you can take out one link pair from the chain, to tighten up the smaller gears' chainwrap.

It's not normally a problem if all the sprockets on the freewheel are the same number of teeth as the same sprockets on the old cassette. But if the smaller ones are less teeth than the old one, there's less chain wrapped on them, and more the derailer has to take up.

 

[creativepart]

@TommyCat... you're talking about the B Screw? Adjust it to move the DR wheel closer to the bottom of the freewheel?

I'm not sure I'm following your 1,2,3, 4... etc. UPDATE: I get it now by following your links to the previous discussion.

@amberwolf I did -- totally by coincidence -- remove 2 full links the day before yesterday. So, the photo was taken a few days before I removed the links. I knew the chain was a tad long. I purchased it at a bike shop in Tucson that gave me a few minutes of time to check out my problem. We thought that a new freewheel "might" need a new chain and so that was attempted. I asked to have the chain left a little long in case I increased the chain ring gearing. Since I"m not I resized the chain on Sunday.

 

[creativepart]

I pulled the crank today and checked out my front gears - 32T and 44T - I never use the 32T ring. I thought I might remove it but it holds on a plastic chain guard and so I left it alone.

I had been thinking of going up to a 48 or even 50T chain ring. But I found out that my crankset is a OEM special order FSA Modular Locking thing made for Specialized that wouldn't allow me to increase the ring without replacing the entire crank set and bottom bracket. So, I'll stick with 44T.

So far with everything I've done, so far, nothing has made any difference.

I'm going to live with riding in 8th gear for the most part for now. I could replace the derailleur, freewheel and micro shifter to 8-speed for about $100 with used parts. I'm considering this but I think I try some of TC's and AW's suggestions first.

 

[creativepart]

A couple of details to add to this,

The derailleur is a Shimano Alivio long cage mtb RD.

When setting the H limit it is as far “out” as it can go. Any further and the limit screw list off its adjustment surface.Turning clockwise the chain begins moving in and running noisily. Turning counter clockwise the chain quiets but cannot be moved any farther out - it’s the limit of travel for the derailleur.

 

[TommyCat]

@TommyCat... you're talking about the B Screw? Adjust it to move the DR wheel closer to the bottom of the freewheel?

Sorry, I don't have a "B" screw. To make sure we are on the same page, let's go over it by the numbers... :wink:

You goal is to move the DR arm as far in the #3 direction as possible. This is positioned by the actions of these three things in balance.

A) The over-all chain length. [See #1.]
B) The position of the DR assembly in relation to the gears. [See # 2]
C) The tension of the DR arm tensioning spring. [See #4.]

Note: Keep in mind the balance part. A change in one will effect the results of the others. Take it in steps just in case everything is not needed.


1) Make sure that your chain is the recommended length. You may shorten it further if needed and possible but start here...
https://www.parktool.com/blog/repair-help/chain-length-sizing

2) Rotate the DR mounting arm CCW, wrapping the chain further around the gearset. Some filing may be needed to allow this.

3) The desired direction you desire.

4) The most difficult part for me as I don't have a DR tensioning adjustment screw. Just a tensioning spring, that by moving it's securing or anchor point of one end.(the hole around the spindle) In the correct direction to increase the tension.
The hole in the 4 o'clock position in the pic below is the new one.

5) In my case I had a self made obstruction being my custom made torque arm. That I needed to reduce in width, to allow the arm to wrap further around the gearset.

As you've noted, the "H" and "L" adjustment screws determine the end stopping points of the DR along the gearset range.
But that's another class...

I like your torque arm, is that custom or bought?

Thanks m8! See the why and how of it's fabrication in POST #16 here...
https://electricbike.com/forum/foru...t-52v-11-5ah-huffy-parkside?p=52309#post52309

 

[creativepart]

FIXED!
I purchased a new DNP 8-speed freewheel and a Shimano 8-speed shifter. This has completely fixed the issue.

The odd thing is I figured the 8-speed freewheel would be shorter over all. But the 8-speed DNP and the 9-speend Sunrace were pretty much the same height - the 8-speed was 1 or 2 mm shorter at most. I know folks like to complain about DNP freewheels but it seems much better built than the original Sunrace.

My rear derailleur is a Shimano 9-speed Alivio but after doing research I found that 7-8-9 all work the same and it's the shifter that does the gear indexing. So, I bought a Shimano Tourney 8-speed. It was easy to index and works OK. I reused the original cable housings because it's internally routed. I find that the thumb upshift works fine at the der but the thumb lever doesn't spring back without some help. I may need some new cable housings.

The new freewheel is a 11-34T and the old Sunrace was a 13-32T and with the highest gear not working I was only using the 8th gear which was 14T. Now, riding on the road in PAS 3 at 20 mph my pedaling keeps up with the motor. It's a big improvement.

Thanks everyone for the help!

 

[2old]

Hate to have you revert to the 1800's, but if nothing else fixes your derailleur problem (might try lubing the cable housing), a friction shifter may work.

 

[creativepart]

I thought I posted an update - it was such a simple fix for the shifter. I found it online - all I needed to do was unscrew the handlebar clamp on the shifter a little. Turns out, if you tighten that clamp too much it binds up the thumb shifter. I had it really cranked on there... if tight it good then tighter is better right? Turns out that's not always the case.

The new shifter works great and it's such a joy having a smooth running 8-speed drive train with an 11T top gear.