Strange Rohloff Sensation when Pulling Away

[Samurray]

Greetings Thorn Forum
Recently I started using a Rolloff. I purchased it new from Germany and it was installed onto my bike with OEM2 dropouts.
Just lately I have noticed a strange sensation through the cranks when pulling away. This happens only (at the moment) under load (rear panniers). It is actually hard to describe but all I can say is that it's like a strange yet very brief 'dipping' in gear engagement. As you push down on a crank there is a momentary... slip is possibly the wrong word... but dip like the rear wheel has rolled down into a small pothole (or something) before the cranks engage fully again allowing smooth acceleration. It almost feels like there is movement in the drivetrain somewhere but I have checked the cranks and bottom bracket - all tight - and the chain, which is new.

Anyone else out there experience this? Is it normal or something to do with the Rohloff that I need to get checked?

Any thoughts gratefully received.
Best
Sam

[geocycle]

Lots of views and no replies Sam, sorry.  I suspect because we haven't experienced the symptoms you describe.  My gut feeling is that it is unlikely to be the rohloff and I'd instead be checking the chain, bottom bracket, cranks, tensioning system, sprocket (is this the old threaded or new splined one?) , drop outs or even wheel skewer tension.

[jags]

welcome Sam sounds to me like the chain is skipping.ant stiff links

jags

[Danneaux]

Hi Sam, and welcome to the Thorn Cycling Forum!

A quick thought: Have you checked cable tension? If the cables are too tight, the shifting/drive action can behave in odd ways. Similarly, if the cable housings are worn, the cables may be hanging up inside and causing some problems.

Best,

Dan.

[JimK]

A new chain on an old chainring could do that.

[StillOld]

In my very limited experience....I have a similar feeling on my Nomad with Rohloff. Feels like a slack pause when first pushing the pedals. I put it down to my chain adjustment as it looks a tad loose. Maybe I need to adjust it through the bottom bracket?

I didn't want to touch anything so have lived with it for the last few hundred miles. Definitely not something wrong with the Rohloff so I'm not concerned.

[macspud]

I have read of something that sounds similar here:

http://www.bike-air.com/Rolhoff-IGH-not-engaging-on-technical-terrain_10704561.html

The same same post about low engagement is also mentioned here:

http://www.bikeforums.net/touring/1033072-rolhoff-igh-not-engaging-technical-terrain.html

It wasn't found to be a problem other than when riding very slowly on technical terrain and ratcheting up and over obstacles whilst in low gear. The slow engagement should be less noticable when using a higher chainring to sprocket ratios as the pedals rotate less before engagement, so may be noticed when using when using the lowest allowable chainring/sprocket ratios and riding in this technical manner.

[Andre Jute]

I've always noticed this phenomenon at changes in effort and ascribed it to running my chain pretty slack. Similar experience by so many other riders makes me wonder if that momentary pause in uptake isn't native to the Rohloff.

[JimK]

Seems like a key question is: does this sensation happen only right after a gear shift? Or is it more like any switch in rider effort, from low torque to high torque, without any gear change?

[Andre Jute]

Seems like a key question is: does this sensation happen only right after a gear shift? Or is it more like any switch in rider effort, from low torque to high torque, without any gear change?

Both.

[macspud]

Seems like a key question is: does this sensation happen only right after a gear shift? Or is it more like any switch in rider effort, from low torque to high torque, without any gear change?

It doesn't seem to be connected with a change in effort but rather when first starting off or after back pedaling.
 

It wasn't found to be a problem other than when riding very slowly on technical terrain and ratcheting up and over obstacles whilst in low gear.

What is meant by ratcheting is the small back pedal fore pedal back pedal fore pedal technique (taking lots of little bites) rather than the circular pedal movement of normal cycling.

[StuntPilot]

I had a similar ratchet feel on applying load on start up. The two things I thought that caused that were:

1: Chain too tight and/or
2: Rear cog teeth having small burrs on the tips due to overdue cog reversal

After loosening the chain and some miles of cycling the ratcheting on starting off stopped. I also filed off the sharpest of the burrs on the cog.

Interested to find out if the was the problem!

[Samurray]

...Feels like a slack pause when first pushing the pedals...

Wow, a lot of replies. Thanks for the suggestions all.

StillOld's "slack pause" is a very good way to describe this phenomenon.
I have checked cable and chain tension and small adjustments to both made no difference. The rear wheel's skewer is good and tight too. The BB (Phil Wood) seems to be fine even though it's clocked around 15000 miles now, and the cranks are good and tight. Other than the BB all components of the drive train are new so there shouldn't hopefully be an issue with the chain/chainring/sprocket relationship. All conform to Rohloff requirements with regards sizing and ratios.

JimK, your question as to whether this happens right after a gear shift (from standing at lights, say) I cannot answer with confidence and need to check. BUT, I am fairly sure it happens regardless of whether I shift just before or remain in the same gear coming to a stop and then moving away. Will double-check this though. For certain, the phenomenon is ONLY ever experienced (by myself) when pulling away from a stop, never when, say, standing up on pedals and exerting extra torque to the drive train on hills.

geocycle, not sure whether the sprocket is threaded or splined. Is there an easy way to tell just from looking at it still attached to the hub?

Thanks all for the welcome and your replies.

[macspud]

...Feels like a slack pause when first pushing the pedals...

StillOld's "slack pause" is a very good way to describe this phenomenon.
I have checked cable and chain tension and small adjustments to both made no difference. The rear wheel's skewer is good and tight too. The BB (Phil Wood) seems to be fine even though it's clocked around 15000 miles now, and the cranks are good and tight. Other than the BB all components of the drive train are new so there shouldn't hopefully be an issue with the chain/chainring/sprocket relationship. All conform to Rohloff requirements with regards sizing and ratios.

Yes, "slack pause" seems like a good description.

Here is a fuller quote from the "Rolhoff/IGH not engaging on technical terrain?" thread on "bikeforums.net"

folks, this has nothing to do with the 'shift' - it has everything to do with how fast the hub engages in technical, rocky, rooty terrain.
for touring, mixed terrain touring, even some types of single track touring i love the thing...

but for pure mtb riding in technical terrain the hub (to me) does not excel.
again, this is not about the shifting... i can deal with the differences in the shifting and the way the gears move, timing, when to shift, etc.

this is what you would compare to a standard hub in 'engagement' - king, i9, etc. all have very little rotation of the cranks before the pawls engage.
the rohloff, by whatever mechanism it engages the drive components is sloppy compared to these hubs, even compared to a mid line shimano.

i can leave the hub in 1 gear, not shift at all, and if i were to pause or re-position the cranks over a technical obstacle (rock, root, we have plenty here!) - the cranks will spin around quite a bit before power goes to the wheel. in my limited, unscientific testing it seems variable, but was more than 15-20 degrees or rotation (compare this to the i9 which has 3 degrees before the pawls engage).

i first noticed this in the spring, when the woods dried out, and i moved to riding more single track. things just felt off. couldn't figure it out until a friend borrowed my bike wanting to get a feel for the rohloff. he hated it, and named the reason... and to me it immediately made sense - i rode my krampus in the woods with the stock build all last fall - when the snow started to fly i put on the studded tires and moved to forest roads / less technical single track - and i built up the rohloff wheel. i rode that all winter - camping a few times, and then transitioned into the woods on it. i found myself fumbling crossing logs or rocks, and stalling out as i came through a switchback (and re-positioned my feet).

to test out the theory i borrowed a set of king hub'd wheels and ran single speed for a week. it made a difference in my confidence and my riding. i then snagged a set of king hub'd wheels with wtb scraper rims - so now i have the rohloff setup and a ss setup (and a 1x5 setup on the king hub'd wheel too...)

perhaps this isn't an issue for others with a different MTB riding style - but i found that i rotate / ratchet the cranks alot....

for pure MTB racing / riding / rock crawling etc. in technical terrain its not the hub for me.
for loaded MTB touring (softbags, etc) - i love it.
for mixed terrain riding i love it (despite its weight...)

i want one for my dirt road / rando bike... sort of.

[Samurray]

...i can leave the hub in 1 gear, not shift at all, and if i were to pause or re-position the cranks over a technical obstacle (rock, root, we have plenty here!) - the cranks will spin around quite a bit before power goes to the wheel. in my limited, unscientific testing it seems variable, but was more than 15-20 degrees or rotation (compare this to the i9 which has 3 degrees before the pawls engage).

The description quoted above doesn't really fit what i am experiencing. The cranks do not spin as such. There is engagement with the hub but it's like the hub attempts to engage a much lower gear momentarily before 'realising' it needs to engage a higher one. Having been out for longer rides last week and carrying some weight at the back, I have discovered that it makes no difference at all whether I pull away in the gear used prior to coming to a standstill or if I select a new gear whilst staionary.
I think in light of all this I will contact Rohloff themselves to see if they are able to explain or shed some light on this issue.