Fitting a Rohloff to a Thorn Club Tour Mk4

[DIAGMONKEY]

Hi,

I am thinking of converting my Thorn Club Tour Mk4 to Rohloff.

Anyone already done a conversion?

Currently the bike is set up with drop bars and 3 x 10 derailleur gears. It has a rear disc brake.

My plan is to swap to Rohloff and Koga Denham handle bars. I already have these items currently fitted to another bike.

I am assume i am going to need either a torque arm or speed bone to secure the rear hub. What's the easiest option with regard to rear wheel removal?

With regard to chain tension what is easier a chain tensioner or something like the Trickstuff Exzentriker?

Thanks in advance!

 

[JohnR]

Rohloff provide plenty of guidance at https://www.rohloff.de/en/service/handbook/speedhub/assembly/torque-anchoring. Will using the OEM axle plate 2 https://www.sjscycles.co.uk/hub-spares/rohloff-axle-plate-ts-oem2-8228 with a bolt through the lower disc brake hole on the Club Tour work? Wheel removal is easy although when replacing the wheel it's necessary to ensure that the fingers on the axle plate slot around the bolt.

I've used the rack mounting hole as the anchor point on my Spa Cycles Elan Ti frame (which was more straightforward than using the steel Elan frame - see http://thorncyclesforum.co.uk/index.php?topic=14396.0). I also use a chain tensioner. It's slightly less elegant than one of the EBB solutions but the is much less expensive and having some slack in the chain makes wheel removal / replacement easier. The attached photos are for the Elan Ti frame.

[PH]

I'd split this project into two - First, find some gear and brake levers to match what you already have and swap the bars over.  Then after a good few hundred miles decide if you want to proceed with the hub.
You have a frame with top tube and steering geometry intended for a hand position ahead of the stem, the new bar puts the hand position much further back, probably too big a difference for a change of stem to compensate for.  That will have consequences which it may not be possible to work out on paper. It might be fine, you might prefer it, but equally it might not.  I've converted two bikes from drops to straights, with bar ends so the hand position wasn't radically different. One was fine the other wasn't and I can't figure out why.
If/when you do come to swap the gearing, I'd choose a Monkeybone and Rohloff tensioner, I've been happy with these, though I don't have much experience with other components for this task.  The Rohloff tensioner keeps plenty of chain engaged with the sprocket, minimal clatter, easily adjusted chanline and good parts availability.  The Monkeybone shares the load with two fittings intended for braking forces, so possibly the strongest part of the frame, the recess guides the plate into position.
The mini eccentrics don't have a good reputation, there's been several come and go, plus they don't offer enough throw.  The long arm is arguably the best torque option, on the basis that when it comes to levers the longer the better, it's just plain ugly.
There's no reason you can't make it work, it'll never be as good as a purpose designed frame and there are choices about what you'll compromise, but the disadvantages are not monumental.

[DIAGMONKEY]

JohnR. Thankyou for the links.

PH. Sounds like a good plan. I spend most of the time using the Denham bars in the forward position, it has kind of inner bar ends. So my hands tend to be placed in front of the stem. it's quite similar to the hoods position on the drop bars. They work do quite well for me on the other bike as they also offer a much more upright position and more leverage for slow speed stuff in the more conventional grip position. But you are right it would be a good idea to run it for a while first with the existing gearing on some longer rides before making a final decision.
I would like a Mercury, they do look a very tidy solution, but do not really want to spend quite a chunk of money on a replacement frame and fork if I don't need to.

[martinf]

Not a Rohloff, but the chain tension problem is the same.

I used a Surly Singleator tensioner when I fitted a Nexus 8 Premium to my large visitor bike with vertical dropouts.

The rationale for me was to have a single pulley wheel pushing upwards, the idea being to have as much chain wrap around the sprocket as possible, while having not much wrap around the tensioner. And only one pulley which should slightly reduce the friction losses compared to the two pulleys on the Rohloff tensioner.

The Singleator has a choice of two springs to push either up or down and the spring tension is adjustable. I use the minimum that keeps the chain tight enough to not fall off, again the idea is to minimise friction loss in the pulley.

Not such a good solution as a proper eccentric bottom bracket as used in Thorns specifically designed for hub gears, but the Singleator works well, it's principal disadvantage for me being that it isn't possible to fit a Chainglider.

I'm keeping an eye out for a replacement Chainglider-compatible frame on the local equivalent of Gumtree - a big old mountain bike with long dropouts  from the late '70s/early '80s would work.

Plenty of small frame bikes turn up locally in the 30-80 euros price range, I've bought two of these in the past couple of years to build replacement bikes for my wife, but I haven't yet seen a suitable large frame.

[PH]

I would like a Mercury, they do look a very tidy solution, but do not really want to spend quite a chunk of money on a replacement frame and fork if I don't need to.

There's no reason it shouldn't work if the fit with the bar change suits you.
Koga's early Rohloff bikes, including the one Mark Beaumont used for his first Round the World record, used the Rohloff tensioner, though I don't know how they handled the torque.  Vin Cox then beat the record with an Alfine hub in a frame not designed for it and an Alfine tensioner. 
Hewitt used to offer their touring models as Rohloff bikes, with both the Rohloff tensioner and long torque arm, ironically the bike that didn't work for me straight bar.
There must be a loss of efficiency, though I doubt it's in the realm of anything I'd notice.  Wheel removal is also somewhat impaired, I reduced the sprocket size on my Joey, from 19 to 15, which made it much easier to clear the tensioner.  Then there's wear, I haven't decided how to deal with this yet, on my Thorn bikes I leave the chain to wear the sprocket knowing they'll still match.  With a tensioner, particularly one with plastic wheels, an elongated chain is going to eat them up.  My folder is the least used bike and replacement wheels are £10, so I'll probably run it till there's an issue and then decide what to do next time round.

[DIAGMONKEY]

Thanks for the help 

Slight change of plan, I am going to stick with the drop bars on the club tour and just use an accessory bar to mount the shifter. I know I find the bike is very comfortable with the current bar setup.

After speaking to SJS this morning I ended up ordering the following items to convert to Rohloff from the current 3 x 10 setup.

OEM2 axle plate + replacement screws
Monkeybone
Rohloff chain tensioner
T shaped Accessory bar to mount the shifter on.

Hopefully the parts will arrive in the next few days as I am off work this week and should be able to complete the conversion by the weekend. 


 

[JohnR]

After speaking to SJS this morning I ended up ordering the following items to convert to Rohloff from the current 3 x 10 setup.

OEM2 axle plate + replacement screws
Monkeybone
Rohloff chain tensioner
T shaped Accessory bar to mount the shifter on.

I presume the rear wheel with Rohloff hub and the shifter / cables comes off the other bike?

[DIAGMONKEY]

Yes the rear wheel, hub and shifter will all come off the other bike.  It's a nice enough bike a non electric Storck Multitask. The previous owner had upgraded it to Rohloff, and it came with the original rear wheel. But the frame is a little to small for me.  I have used it over the winter to commute on, but its not as comfortable or as quick as the club tour on longer rides.

[PH]

Thanks for the help 

Slight change of plan, I am going to stick with the drop bars on the club tour and just use an accessory bar to mount the shifter. I know I find the bike is very comfortable with the current bar setup.

Look forward to hearing your impressions when it's done, and seeing the photos of course. 
I've never used the shifter anywhere other than on a straight bar though I know plenty do.

[mickeg]

Just an FYI, I experimented with several locations for the Rohloff shifter on my Nomad Mk II.

I suspect that just about any location would work if you are mostly on pavement (tarmac).  But in my case, my Nomad was often used on gravel or single track or 4X4 only type roads.  And there were several times when I wanted to be able to shift while simultaneously wanted to keep my hands on the bars where I had leverage for steering.

After my Iceland trip in 2016 when some of the interior roads convinced me that I wanted to move my shifter further from the steerer tube for more leverage when steering, I went with the Hubbub Adapter to mount my shifter on the right side bar end.  Been very happy with that decision.

I have used bar end derailleur shifters on several bikes going back to the 1980s, thus reaching to that location for me is second nature, but if you have not used bar end shifters before, that might not be a position you want.

I used a pair of V brake noodles to route my cables further forward.  Second photo shows the noodles at the shifter.

Do what you want, just wanted to make sure you knew about this option too.  I have read a few notes on the internet that the adapter can come loose, so I tightened mine up REALLY good to make sure it stays tight in the handlebar.

[martinf]

On my Thorn bikes equipped with drop bars and Rohloff gears I first tried the accessory bar, then, like George, I changed over to a Hubbub adapter to put the shifter in the same position as the derailleur bar-end shifter I had used for many years.

A cheap alternative to the Hubbub adapter is to graft a piece of 22.2 mm MTB handlebar into the end of the drop bar, I did this using a piece of smaller diameter alloy tubing from an old garden chair to connect the drop bar to the piece of 22.2 mm bar internally, with epoxy glue to fix the parts permanently together. It worked well for several thousand kms with at first a Shimano Nexus 8-speed twist grip then a Shimano Alfine 8-speed Rapidfire lever, so should work just as well with the Rohloff shifter.

I also have a Brompton with Rohloff hub. On that bike I used a Brompton front lamp bracket, as the straight bit on the bars (M-bar type) is too short to fit the Rohloff shifter inboard of the brake lever. This setup also works well for me.

[DIAGMONKEY]

Well the parts arrived today, just after 4pm. Great service from SJS, both for the advice and the swift packaging and posting, I only ordered them at lunch time yesterday.

Monkeybone, axle plate and tensioner were all easy to fit. Rear wheel drops in and out reasonably easily as I am using a 16 tooth sprocket. Certainly no more awkward than a derailleur bike.

I ended up fitting the accessory bar behind the steering tube, so it sits over the top tube, rather than between the steerer tube and the bar as I had intended. I had not thought about the bracket and cable run for the cantl brake fitted to the front of the bike. I was a bit worried about clearance for my knee, but a quick spin down the road and it seems fine. Changing gear is no problem. My hand seems to find the shifter easily enough without looking even after such a short run.

I will give the bike a proper run out tomorrow, see what its like over the rougher sections of road and when I'm out of the saddle on a couple of the climbs. If it turns out to be an issue, I can always nock up a homebrew hubbub as suggested or switch the bars out for the Koga Denhams.

[JohnR]

Another Rohloff shifter-compatible handlebar option is the Van Nicholos drop bars https://www.sjscycles.co.uk/handlebars/400-van-nicholas-rohloff-drop-bars-318mm-clamp-black.

[John Saxby]

One more photo example of horses for courses, à chacun son goût, whatever:
Have attached below a side-on view of the twin T-bars I had fitted to my Raven, the upper & smaller T-bar holding the Rohloff shifter on the right side and my bell on the left.

I found this arrangement allowed me to cant the shifter rearwards about 15-20º, so that I held the shifter rather more like a doorknob. I found this arrangement worked well for me, and have continued it with my new (spring 2022) Mercury Mk 3.