Installing a Rohloff in the Milan GT

I’ve like the Rohloff internally geared hub (IGH) for many years. I have one installed on my tandem recumbent bike, and also have a Rohloff in the WAW velomobile.

Many velomobiles have a rear wheel that is supported and attached on one side of the wheel (the right side); they use a customized axle, but this design doesn’t allow installing a Rohloff. The Rohloff needs to be supported on both sides. The WAW has aluminum machined drop outs that attach to the rear of the shell; here is a link to my installation of the Rohloff in the WAW.

https://flic.kr/s/aHskyzUezb

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Machined drop-outs on the WAW; torque arm fixing bolt can be seen at the top of the left drop-out.

My Milan GT came to me set up with a 10 speed derailleur on the rear (and 2 chain-rings on the front, 34 tooth and 60 tooth). It has a metal U-shaped bracket at the rear wheel, that serves as chainstay and as the attachment point for the rear shock absorbers. Unfortunately, the chainstay didn’t have a torque arm fixing point. Here is a view of the chainstay; this is looking rearward on the right side, derailleur at the back end of the chainstay.

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The chainstay; looking rear-ward on the right side. The gray foam support for the seat is held in place with velcro.

So I put the Milan upside down in a cloth sling that my wife made for me; suspending the velomobile from the ceiling makes working on the velomobile much easier on my back. Removing the chainstay wasn’t too difficult; I removed the rear wheel, unbolted the shocks, and the forward section of the chainstay is mounted to the body using some polyurethane bushings, so un-bolted those. I had to remove some of the bolts for the idler wheel as well.

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Much easier on my back to work on things this way. I use the rolling seat for comfort
Upside down velomobile, and chainstay removed.

The torque arm fixing point (or whatever it’s officially called….) is needed to keep the hub internals from rotating, otherwise the hub won’t work! Once I had the chainstay removed, I determined where I wanted the torque arm fixing point to be. The torque arm on the Rohloff can be set at various positions around the hub (pointing to 9 o’clock, or 3 o’clock, etc…) . Since there is so little space to get my hands up into the rear wheel opening I felt that it made the most sense to have the fixing point to be directly above the left side drop-out.

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The torque arm fixing point will be right above the left side skewer lever. Not a lot of room for my hands here!

I welded a piece of flat stock onto the chainstay, cleaned it up and painted it (found some matching spray paint in the shop), and installed it back into the velomobile.

Flat metal stock, cut and ready to be welded onto the chainstay for torque arm fixing point.

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Here’s the Rohloff wheel set into the chainstay; the black U shaped piece above the drop-out is the torque arm
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Torque arm fixing point welded and painted, ready to re-install in the Milan.

While the paint was drying I installed a new Rohloff shifter and new cables with housings. The Rohloff shifting mechanism leads to the left side of the wheel, derailleur cables lead to the right side. I set up the shifter box and installed the cables after reviewing YouTube videos; it’s not difficult but does need to be installed correctly.

Before putting the chainstay back into the velomobile I set the hub in the chainstay, and checked the alignment of the drive cog of the Rohloff with the chain tensioner. Bummer….. it doesn’t line up! The chain tensioner comes with various thickness spacing washers that are used to line things up properly, but due to the narrow width of the drop-outs, I needed a special longer mounting bolt.

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Can’t get the tensioner and the cog lined up, needs a longer mounting bolt

Found out that my supplier for Rohloff components http://peterwhitecycles.com would order the longer bolt, but it would be at least 3 weeks before it would arrive (took about 8 weeks total)… and since the installation of the shifter cables for the Rohloff deforms the end of the cables, it is very hard to remove and then re-install those cables. And a velomobile requires longer than typical cables, so rather than removing and throwing away brand new cables I moved the Rohloff shifter in towards the center of my tiller as far as it would go, and re-installed the shifter for rear derailleur, and of course I had to install new cables and housing since I had cut off the older ones (lesson learned!) I’ve been riding with 3 shifters on the tiller since then:

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Riding with 3 shifters until I can complete the Rohloff conversion.

The longer mounting bolt arrived yesterday, and since it’s going to be a rainy weekend in my area it’s a great time to finish the conversion. The longer mounting bolt isn’t that much longer, about 5mm longer than the standard bolt.

The longer mounting bolt on the left is only about 5mm longer than standard bolt.

And I ordered a new tensioner. I purchased this Rohloff wheel and hub from a friend who put quite a few miles in with the wheel, and the tensioner cogs are pretty tired. The new tensioner showed up missing the tensioner spring? I’ll take the spring off the older tensioner for now. (I have since found out that it was an oversight at Peter White cycles; someone broke a spring, and this was the tensioner that donated a spring to that poor rider!)

New one on the left, missing it’s spring. Really need that to function properly πŸ˜‰

The tensioner is needed to (obviously) maintain tension on the chain, and it also takes up chain slack when switching between chain rings on the front. On the WAW I have 34-42-52 tooth on the front, hopefully the tensioner can take up all the chain slack between 34 and 60 tooth on the Milan.

I used an online calculator to determine, for curiosity sake: if I were to leave the 10 speed 11-36 cassette on the rear, what chain rings would I have to install on the Milan to get the same range as the Rohloff gives me? How about a 26 tooth switching to a 74 tooth? That’s a LOT of chain to adjust for….. As a metric I used an online calculator to indicate the speed attained while pedaling 90 RPM. The Rohloff affords a very wide range of gearing, very helpful when riding a velomobile in hilly country. On a typical ride I can see 4.3 mph up steep hills, and 54 mph or more downhill! The downhills are far more fun, FYI πŸ˜‰

On my current 34-60 tooth /11-36 cassette, pedaling 90 RPM gives me 6.6 mph to 38 mph. I can’t put any more power to the pedals above 42 mph.

With the Rohloff using the same 34-60 tooth chain rings in the front, 90 RPM will give me 5.1 mph to 47.1 mph. (This assumes that I can run such a wide size difference in the chain rings). It may sound ridiculous to want to pedal at 47 mph or more, but increasing the speed you are traveling when you’re heading to an uphill roller will give you more kinetic energy, and allow for better climbing or rolling up and over that hill. And naturally being able to climb steep hills will be much easier with the Rohloff installed (I regularly have to climb 13-14% grades).

UPDATE: July 2, 2019

I finally got the tensioner in and I believe the proper amount of spacers to line up the cog and tensioner. Took quite a few tries: install the tensioner, tighten the bolt using hex wrench, with limited turning ability because the wrench is hitting the body of the velomobile, or the chainstay, or the shock absorber. Put the wheel back in and check it. Not quite right…. Take it back out, change out the spacers, try again…. not quite right….

On the left side of the rear wheel there is an area cut out so that you can reach your hands in to open or close the quick release for the rear wheel. Barely large enough for my large size hands to get in there; but it also leaves a rather large gap in the floor of the velomobile, and I could easily envision something like keys rattling around and eventually falling out through that gap, through the rear wheel cover and onto the road.

And I had to use a cut-off wheel to cut back a bit more of the carbon fiber on the right side of the wheel housing; the Rohloff hub is wider than the wheel it’s replacing, and the spokes were rubbing. Once I had that all done and the spokes had solid clearance all around, I realized how much of that rear wheel is exposed to the interior of the velomobile, and luggage or things stored in the rear of the velomobile could cause a bit of trouble.

You can see it’s a large opening; have to cover this over with some pieces!
This is the left side; the upper flatter section is the floor of the velomobile

So, time to make some CF pieces to fix these! I used the mold from another project to make up the smaller piece for the left side, and taped 2 pieces of coroplast together into a simple L mold to make the larger piece for the right side. To give good clearance for the wider hub, I put a dumbbell onto the piece when it was being vacuum bagged, so it would cure with a bit of a curve.

Vacuum bagging 2 pieces at same time. Dumbbell is to give a bit of a curve, to match curve of the wheel.

I let these 2 pieces cure overnight, and the next day I removed them, and cut to fit. Not the prettiest things or beautiful cuts, but they work for what I wanted, and it was a quick job! Some days that’s important, particularly on pieces that serve a needed function, but looks aren’t as considered.

Once everything is ready, this is the rear wheel fairing that gets screwed down, holds the new pieces in place.

For the left side piece, I cut it to form tabs that slip in behind the walls of the wheel well; this holds my piece from flapping out toward the wheel. I put some small velcro tabs on the underside of the part, to hold it in place until I screw the wheel fairing back on. I also lined up the part so that one of the wheel fairing screws will go through the new piece, helping to keep it secure.

On the right side, it’s notched at the rear to sort of lock onto the edge of the cut out area. I made tabs on the parts that pass left and right of the hub; used some strong velcro to attach to the wheel well on the inside of the velomobile.

Part of this was also done since I have time on my hands, waiting for new chainrings for the front. As I feared, the 34-60 tooth combination up front means too much chain for the tensioner to handle. I know, others have used different makes of tensioners, or used derailleurs as tensioners, but I guess I’m just keeping it all Rohloff….

Since I have a Rohloff in the WAW with a 34-42-52 on the front, I took the tail cone off the WAW, to see how far the tensioner moves between 34 tooth and the 52 tooth, and to see if a larger chainring was possible. I ordered a 34 and a 35 tooth for inner chainring, and a 52, 53, and 54 tooth to try for the outer chainring. While I was on the phone with Peter White Cycles I also ordered 3 lengths of chain, the chain on the Milan looks good but if I’m replacing chainrings, I should replace the chain. (The 13 tooth cog on the Rohloff is nearly new, and they are steel and reversible, so that will stay).

And as I was finishing up with the installation of these 2 pieces, I realized the 24 hour CF piece that I made to protect luggage from the chainstay movement meant I was also giving up much-needed luggage space, and also potentially losing air flow through the velo. So I’ve added another project idea to my list! That idea will have to wait for another post, but I have this sneaking suspicion it will be sooner than it should be πŸ˜‰ Sometimes these projects just grab my brain and won’t let go…. I’m driving on an errand, and my mind is going through how to make the mold, what material to use, try this gelcoat instead of that, etc. etc…

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