any Thorn Rohloff experts in Herts who could give some technical expertise?

[Brignall]

Hello all
I have recently bought a used Thorn Mercury with the Rohloff hub. Love the bike but it being my first hub geared bike, I don't really know how it works/ and what is normal.

I was wondering if anyone lives near me in Letchworth in Herts who might be able to spare me an hour to answer any questions I have, and look at the gearing etc. For example, the bike hub appears to have quite a lot of drag when not being pedalled, but I have no idea whether it is normal or not.

I think the bike has been very well looked after and the hub is lovely and smooth.

I figured that if anyone knows it will be someone in this forum. My home phone number is 01462 676830 if anyone's in the area and can spare an hour. Or message me
many thanks
Miles Brignall 

[PH]

Congrats on the new bike.
I'm not local enough to offer a visit, but on the question of drag, Rohloff offer a test, which is basically to get the wheel spinning in gear 14 and the wheel should continue rotating at least 15 times after you stop.  Before you do that, just check the tyres isn't rubbing on the guards or frame and that the brakes aren't catching.  Mark a spoke or the tyre to make counting easier, or film it.  My Mercury rotates 19 times and the Nomad 16 averaged over 5 spins.  That sounds poor compared to a derailleur wheel, but it's a level of drag you're not going to feel while riding.

https://www.rohloff.de/en/service/handbook/faqs#c9471

[Andyb1]

I find the same thing Miles.  If I coast down a hill on my Rohloff geared bike with my wife’s bike as a datum, my wife’s bike is faster: if I pedal but do not apply power then I accelerate towards her speed.
If I am riding my derailleur geared bike we coast down the hill at a similar speed.

I also feel a de-acceleration if I stop pedalling between gear changes but this is difficult to quantify - it just feels like the bike slows for an instant.

Interesting that you mention this as I have not seen it reported elsewhere.

Otherwise Rohloff gearing works well, and I can live with this foible.

[PH]

I find the same thing Miles.  If I coast down a hill on my Rohloff geared bike with my wife’s bike as a datum, my wife’s bike is faster: if I pedal but do not apply power then I accelerate towards her speed.

Have you tried the spin test on the Rohloff website, linked above?
If you're noticing a difference between rotating the cranks and not, you could also have some drag in the seals, do the cranks rotate while pushing the bike? Details of this is in the same link.
Freewheeling downhill is best done in 11th, direct drive, there's the least engaged and it's quieter. The difference shouldn't be significant but every little helps.  I always think my Rohloff is freewheeling slower, but a couple of unscientific roll down tests shows little if any difference.

[mickeg]

Hello all
I have recently bought a used Thorn Mercury with the Rohloff hub. ...
... For example, the bike hub appears to have quite a lot of drag when not being pedalled, but I have no idea whether it is normal or not.
...

By drag, I assume you mean that when you coast, the pedals still want to turn around.  Somewhat normal, varies with gear.  But it should not be the kind off drag that makes you noticeably slower than everyone else in the group.

If you want to try the oil change yourself, it is quite simple.  But Rohloff recently changed their recommendation for lube oil to 12.5 ml which is a smaller volume than before, the video probably is based on older numbers.  After an oil change, a drop or two of oil on the floor under the hub is nothing to worry about.
https://www.youtube.com/watch?v=fVhmgqICNhU

There is a LOT of info in the Living With A Rohloff publication.  A bit dated and somewhat opinionated, but still worth being aware of.  The download is huge, do not attempt on a slow connection or a limited data plan.
https://thorncyclesforum.co.uk/index.php?topic=13710.0

I do not have a Mercury, I do not know if the chain adjustment on that is the same as on my Nomad Mk II, so I can't comment on that.

When you are new to a Rohloff after a lot of experience with derailleur bikes, the first thing you might want to do is tighten up the gear cables.  Don't.  They should be quite loose.  On my bike when I am in a gear, say gear 11, my shifter is anywhere from 10.5 to 11.5, there is that much slack in the cables.  If the cables are too tight, it might not shift well.  The indexing is in the hub, not the shifter, that is why the extra cable slack.

A lot of hub noise in gears 1-7 is normal, 7 being the noisiest.  Gear 11 is direct drive.

The Rohloff manuals are on line, but not exactly sure where.  Rohloff has a website with that sort of thing. 

I think you will like it.

[Andyb1]

PH said
‘Have you tried the spin test on the Rohloff website, linked above?’

Not yet, only read it in your link - interesting how different your two bikes are.

Yes the pedals do rotate when pushing the bike forwards.  I will do an oil change shortly so I will try what the link suggests and add a drop of the thin flushing oil on the seal.

As below, the effect is there but is not a great problem.   If I am freewheeling it is usually because I don’t want to go any faster!

When I first had the hub it was quite noisy when freewheeling but quietened down by about 1000 miles.  At 5000 miles it is now quiet and smooth.

[Andyb1]

Thanks for that link PH.  Lubing the seal reduced the drag that turn the pedals when pushing the bike forwards so must also reduce drag when freewheeling.  I had not lubed that seal before, must remember to do so in future.  I actually used a Halfords spray designed to lubricate nylon and rubber which also flushed out any debris from around the seal.

[Brignall]

Thanks for the advice and tips. Having done a bit more research it seems the drag described is normal - if somewhat different to what I am used to. I'll read the living with a hub as listed above.
Doing maintenance on a standard bike is easy - this feels rather daunting. Hopefully not too much of it. thanks
M

[geocycle]

Thanks for the advice and tips. Having done a bit more research it seems the drag described is normal - if somewhat different to what I am used to. I'll read the living with a hub as listed above.
Doing maintenance on a standard bike is easy - this feels rather daunting. Hopefully not too much of it. thanks
M

The best thing about the rohloff is not having to do much maintenance.  There is far less need to tinker than with a derailleur system which some of us find hard at first.  Really just changing the oil once a year and oiling the chain occasionally with a simple wipe down is enough.  I was initially too concerned about chain tension and the eccentric adjustment whereas in practice the less you touch it the better.  Enjoy the ride!

[Brignall]

"the less you touch it the better" is my kind of bike....

[PH]

The best thing about the rohloff is not having to do much maintenance.

+1
I give my bikes an annual service and thorough clean, including the oil change.  In between I oil the chain and keep an eye on brake pads, very occasionally the chain needs the tension adjusting between services.  Apart from punctures, that's it.

[PH]

PH said
‘Have you tried the spin test on the Rohloff website, linked above?’

Not yet, only read it in your link - interesting how different your two bikes are.

Both are above 15 revolutions, I'm happy with that. I wouldn't want to attribute the difference, but it isn't quite like with like, the Nomad has smaller and heavier wheels, the hub in the Mercury has an extra 100,000 miles running in.  Plus, although I've tried to get the wheels spinning at exactly the same revolutions, the gearing is difference so I can't guarantee it's exactly the same.