Author Topic: Thorn Nomad chain replacement + sprocket & hub question  (Read 217 times)

KvBCycles

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Thorn Nomad chain replacement + sprocket & hub question
« on: September 12, 2019, 10:06:18 AM »
Good morning all,
My nomad and I are on tour and the bike has just passed the 10k km mark.
At about 5000km I had the original chain shortened and the EBB bracket set back to 0 (3 o clock) and from there adjusted as required.
I cleaned and lubed the chain regularly along with general cleaning of the chainring and sprocket. It's been running beautifully, quietly.
Until a few days ago my transmission started to develop a creak and click sound. I removed the chain, cleaned everything and reversed it but the noise persists.
I then replaced the chain (it needed to be replaced) with a shimano 9 speed chain, flipped the chainring but still the clicking and creaking persist on powerstroke, particularly the left crank. I haven't yet  removed and greased the pedals, I'll do that next.

In the event its not a simple greasing of the pedals what further maintenance can I undertake to get back to a silent drivetrain.
I'm currently in Croatia, I don't have a spare rear sprocket or the removal tool. There aren't any rohloff vendors here that I'm aware of and the one bike shop I visited hadn't seen a rohloff before :) so I opted to not do anything in the event they made it worse.
I'll be in Barcelona in a few weeks (but have about 1000km to ride) and I've contacted them and they confirmed they can help with any issues I have.
In the meantime, have I so far done the correct things in replacing the chain and flipping the chainring? I've done about 150km since doing that.
Looking at the teeth of both they both appear to be in good condition, the teeth don't appear to be worn very much at all.
I've got the BCD 104MM 44T chainring and the 19T sprocket.
Any advice would be much appreciated.
Thank you,
Karl @kvbcycles

julk

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #1 on: September 12, 2019, 12:23:55 PM »
Karl,
Check and tighten everything around the drive train.
Pedal bearings, pedals into cranks, cranks onto bottom bracket axle, bottom bracket into eccentric, chainring bolts, eccentric fixing bolts.
Any slight movement in this area will likely give a creak which is very difficult to pinpoint.
My chainring can be moved ever so slightly when being fixed in place - is yours truly centered after being reversed?
The only time I had a noise like this it was a loose chainring boltů

Enjoy the tour.
Julian.

Matt2matt2002

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #2 on: September 12, 2019, 12:41:11 PM »
My click turned out to be the pedals bearings.
New pedals, no clicks.
I had already tried the chain reverse and chain ring bolt tricks.
So annoying after having such a silent ride.
So satisfying when solution found.
Good luck with your own solution.
Never drink and drive. You may hit a bump  and spill your drink

geocycle

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #3 on: September 12, 2019, 12:47:31 PM »
I was about to write the same as Julk.  This doesn't sound like anything to do with the rohloff to me.  Be systematic starting with the easy things.  Clicks tend to be cranks, EBB, chain ring bolts, pedal threads, gravelly noises chains and bottom brackets.  If you can borrow a pair of cheap pedals that would help eliminate one source. 
 

mickeg

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #4 on: September 12, 2019, 03:46:39 PM »
A year ago I had a clicking noise that I diagnosed as in a pedal (Shimano A530), changed pedal with another bike I was not currently using.  This year the other pedal started clicking.  Greased both but the bearings appeared to be tight so I did not touch the bearing adjustment, ridden about 100 km since with silent pedals.

I have had a clicking noise that I thought was drive train in bottom bracket area, finally found it was a rack bolt that was tight but not tight enough.

And a clicking noise that was a non-drive side bottom bracket bushing (UN55) that was tight but not tight enough.

And a creaking noise that was a crank arm (square taper) that needed tightening.  This type of creak is time critical, if you ride too much with this too loose you need a new one.

I have heard of other people having seatpost clicks that they thought was from bottom bracket or pedals or crank, etc.  There are many potential sources of clicks and creaks.

I wear shoes with SPD cleats, the shoe soles often squeak a bit on the pedal as I pedal, but I consider that to be normal.

I agree with the others, likely not a Rohloff problem.

Greasing pedals can be tricky, some pedals have bearings that once loosened up can be very hard to keep tight.  Also, some pedals like Shimano M324 use an odd expensive tool to tighten the bearings.  I mentioned I greased my Shimano A530 pedals above, for that a very inexpensive tool is used,
https://www.sjscycles.co.uk/tools/shimano-tlpd40-spd-clipless-pedal-axle-removal-tool/

To diagnose pedal or crank clicks and creaks, I often stand on one side of the bike, hold the handlebar with one hand while applying the brake lever and the saddle with another hand.  Then stand on one foot while using the other foot to push down on the pedal.  Sometimes that will cause the click or creaking noise. 

For example, I thought my clicking noise was in a pedal but standing on the side of teh bike, it is easier to hear exactly where the clicking or creaking sound is from and in one case I noticed the click was from the back of the bike and I eventually figured out that I had a rack bolt that was not tight enough, pedaling caused frame flex and that frame flex caused the rack to shift the position slightly on the bolt which caused the clicking sound.

You might have to repeat this on each side of the bike a few times to find the location of a click or creak.

If that fails to find the problem, just start tightening and lubing everything in sight.

If you try to remove and re-grease something like pedals, watch about 3 you tube videos first, that usually tells you what you need to know.
« Last Edit: September 12, 2019, 03:49:37 PM by mickeg »

KvBCycles

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #5 on: September 13, 2019, 12:49:04 PM »
Morning gents, thank you for the advice.
What I've managed to do is visit a bike hire shop here in Rovinj and borrowed a pair of their pedals, unfortunately cnc persisted.
Before putting my spd's back on I got some grease from the shop and greased the pedals nicely and fitted them back on. I then removed the seat post, greased and fitted. I then went over what I could, tightening the fore and rear panniers, chainring bolts and EBB bolts.
Took a ride up a hill and it seems like it's sorted...a lot quieter with an occasional click. Having a rest day today so will find out tomorrow if it's sorted.
Thanks again!
Karl

John Saxby

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #6 on: September 13, 2019, 03:50:32 PM »
Quote
seems like it's sorted...a lot quieter with an occasional click.

Glad to hear you've made some progress, Karl. I had similar problems with my Raven in June/July, and following the same drill as you, I've reached the same spot as you.

Not quite a "conclusion", but for the moment, there's no major problem.  So, I've decided to adjust my expectations & live with "an occasional click".  (Until it bugs me enough that I repeat the whole bizness...)

Enjoy your tour!

KvBCycles

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #7 on: September 19, 2019, 02:04:55 PM »
Afternoon all, so quick update...
CNC returned with vengeance! I'm on the Croatian islands and there are no bike shops as such, more bike rental shops. The extent of their help has been to lend me a pair of pedals for testing, fine, and some crazy suggestions like my entire drive transmission is finished and needs replacing (this typically after they see the eccentric bracket) haha :)
I gave up with these guys. Found a scooter mechanic, asked to borrow his tools, no problem, popped off the crank nuts, couldn't remove cranks, need the tool, cleaned best I could and then used his spray lube to flush dirt and lube...decided not to muck about no more...just get me to Zadar :)
Put it back together, test of tasty hills over 20km and its now MUCH better, slightest of clicks so think I'll replace bb anyway. Found a shop in Zadar with the shimano un55 bb so going to head there and replace when I can. There's a decathalon in Zadar too so may use their workshop to do the job. Downloaded bb instructions off sjs website (so handy) and it looks straight forward, just need crank puller and spline tool, hopefully decathalon has them, usually they are really good. As far as I'm aware there nothing special to do when removing and installing due to it being within the ebb.
Otherwise, Croatia has beautiful riding, lots of gravel track if you like and the Thorn, despite CNC, is handling it all with aplomb! :)

geocycle

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #8 on: September 19, 2019, 04:29:57 PM »
Thanks for the update.  You could well be correct about the BB and/or a crank arm.  I've replaced a BB in an eccentric twice.  The first time was challenging as the BB was pretty stuck.  I eventually felt it move against the bolts and they scored a 5mm groove in the EBB -not terminal but annoying.  I then removed the whole thing, used a vice to secure the EBB and put some big levers on the BB.  The second time on a different bike all went very smoothly.  I simply tightened the EBB bolts a bit more and removed the BB as you would in a standard frame.  Hope your extraction goes smoothly

Pleased your trip is going well!
 

mickeg

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Re: Thorn Nomad chain replacement + sprocket & hub question
« Reply #9 on: September 19, 2019, 06:02:36 PM »
You mentioned UN55, so I assume it is a square taper crank.  Using a crank puller is pretty simple, but on occasion I have seen used crank arms for sale where the threads that the puller goes into have been stripped.  Not sure if the puller was not threaded in far enough or if some other problem happened.  But is does suggest you need to make sure it is threaded in far enough.  The other way that could happen is if you did not remove the bolts before you put the puller in, then the crank is still held onto the bottom bracket and the puller can't remove it.

I have to pull my crank arms off to fit my bike in an S&S case, so I carry a crank puller in my tool kit.

The Shimano UN55 bottom bracket is pretty reliable, but any component can go so maybe that is it.  I had a subtle clicking noise on my Nomad for maybe a thousand miles, could not diagnose it.  Finally decided to change the bottom bracket (I had a UN55 installed).  Pulled off the crank arms, then when I went to pull off the left side bottom bracket bushing, it was not loose but it was not as tight as it should be.  So I tightened it up instead of pulling the bottom bracket off the bike.  Decided to see if the not quite tight enough bushing was the problem, so I reassembled the crank, and it has worked fine since.  That was three years ago.

On the bottom bracket, one side is left hand threads (like pedals).  I do not recall which side is left, an internet search would tell you which.  Remove the left side first.  Upon reassembly, install the left side last.  Make sure both sides are tight when you assemble it.

I have no clue what length spindle you would need on a replacement UN55, it varies by crankset.  My spindle is about 10mm shorter than would be ideal on my bike, thus my chainline is off by 5mm.  But that was intentional as I did not want my pedals to be wider on my Rohloff bike than on my derailleur bikes.  But if you could only get a UN55 with a spindle that is more than 10mm different than your old current bottom bracket, your chainline might be off enough to cause more wear on some of the parts.  If the spindle is within 10mm of the correct length, I think that is good enough.

The Nomad eccentric is Aluminum, the UN55 threaded parts are steel.  So, putting some grease on the threads could prevent future dissimilar metal corrosion.  A new one also likely has some blue threadlocker on the threads to help keep it from coming loose, that would also help prevent corrosion.

Good luck.