Friday, 19 February 2010

Getting used to the Rohloff Speedhub

I'm getting used to the Rohloff Speedhub and I'm enjoying my first experience with hub gears!

Rohloff Speedhub - now used

Rohloff gear changing is usually easy and effortless. There's a delicate "click" from the hub gear box, transmitted through the cables to the shifter, on every shift action. You do need, though, a light touch with the shifter and a small synchronised lift of pedal pressure to operate the system effectively and this took me a bit of time to master. At first, I was too heavy-handed and kept shifting 2 gears at a time or 'blocking' gear changes by not lifting pedal pressure enough!

I still occasionally fluff the 'difficult' shift from 8th to 7th, by forgetting to back off. This triggers the hub's protection mechanism and puts it temporarily into the top gear (14th). Of course this usually happens on a hill and can lead to a moment of panic as you're simultaneously trying to lift the pedal pressure to change down and maintain forward momentum! A couple of other gear changes seem to get 'blocked' more than others (9th to 8th especially), if there is any amount of torque on the cranks when you twist the shifter.

I've picked up a couple of Rohloff gear changing techniques! If you change gear when the cranks are approaching vertical you hardly need to lift off pedal pressure because in that position there's very little torque going through the cranks. I've also noticed it's actually easier to change down from 8th directly into 6th! (I don't know if this is recommended though)? A friend of mine, also with a Rohloff geared bike, commented he often does this as well!

Unscrew the EX box (below the dropout) and the wheel is easily removed
You can also see the small torque plate that needs slotting in the dropout (below the QR lever)

Sometimes with hub gears, back wheel removal can be tricky. On the Nomad, the use of the Rohloff EX Box has made rear wheel removal no more difficult than my derailleur geared bikes. Put the Rohloff into 14th gear, release the V-Brake noodle, release the EX Box by undoing the knurled thumb screw and drop the wheel out. Easy. (This is also somewhat easier than Rohloff's alternative gear change mechanism the Internal Gear Mech. Here, two concertinaed gear cables have to be released using the special cable joiners. Some people have reported these are difficult to operate with cold and/or wet hands).

Although it's widely stated you can change gears with the Rohloff hub while stationary, you can only do so if there's no torque on the cranks! Once, I was slowly avoiding an obstacle on a trail and I was in a relatively high gear and also on a slight incline. As I navigated around the obstacle, I tried to select a lower gear but the shifter wouldn't rotate because I was having to press on the pedals to counteract the slope. I ground to a halt, desperately trying to change gear, but couldn't and just managed to release a foot from the pedal to avoid a prat-fall!

One slight bug-bear I have with the Rohloff hub is losing momentum both at the start of inclines and riding into headwind. The gaps between gears 9, 10, 11, 12 (my normal riding ratios on 40x16) are bigger than I'd like. I sometimes feel I'm grinding along in 11th, but after changing down, I'm spinning more than I want to in 10th and vice versa. The Rohloff gear ratios are all evenly spaced (13.6% difference) and although the spacing of the 1-7 climbing ratios feels OK, I'd prefer the spacing of the 8-14 ratios to be closer together. I often feel I'd like a gear 9½ or 10½. I'd consider sacrificing some of the 526% gear range for slightly closer normal riding ratios. It's a shame that aspect of the Rohloff isn't configurable...

40x16: 13.6% diff: 526% range1821232730343944505765738495
38x16: 11.6% diff: 410% range2123262932364044505562697786
Closer normal riding ratios, if the gear difference was reduced

I also find it mildly irritating having to move my hand from the handlebar grip (and shift my balance slightly) to operate the Rohloff shifter. It's only a few centimetres of movement, but I feel it spoils 'the flow' a little. (I've used Campag Ergo levers exclusively for many years and appreciate greatly this superb way of changing gears).

Not very far from grip to shifter, but too far not to have to shift your balance to operate

On the subject of noise, there is no real problem to report! Actually, 8-14 on my Rohloff bike is quieter than my (well maintained) Campagnolo geared road bikes! I only hear the tyres when rolling along in these gears. The freewheeling noise is also less, although Campag freewheels aren't that quiet. Of course, I wish the noise and whirring of the Rohloff reduction gears (1-7) wasn't present, but it's not really that intrusive. I do sometimes find myself holding onto 8th gear, when I should be in 7th, so the noise and whirring obviously has some impact on my psyche. It is only really 7th, though, that's any 'problem' and only for the first few seconds. After that I settle in and get on with the job of climbing the hill...

Overall, I'm very happy with my Rohloff setup. With it's idiosyncrasies duly noted, it is working perfectly and has been great for winter weather riding! The joy of using one on wet and muddy rides (that would be all of them so far then Shaun) and the subsequent easy chain cleaning and zero maintenance regime is a revelation! As long as I don't have any serious trouble with the hub, I will feel that I've made the right choice for my expedition touring bike's transmission.

Tuesday, 16 February 2010

East Anglian Air Ambulance

Today, I cycled to one of my current regular cafe stops - Rosie's in the little village of Southill, Bedfordshire (Map).

While chatting to the proprietor, as I usually do, she mentioned that her husband was involved in fund raising for the East Anglian Air Ambulance, which services the English counties of Bedfordshire, Cambridgeshire, Norfolk and Suffolk. She also kindly gave me a lapel badge. Thanks!

Bedfordshire Appeal Lapel Badge for the EAAA

Although I hope I never need to be a 'passenger' in an air ambulance, I'm perhaps grateful that a helicopter and medics are on stand-by to assist with any mess, if the unthinkable happens and maybe, just maybe, the extra rapid transit to hospital could make the difference...

Most, if not all, air ambulances in England and Wales are kept airborne entirely through fund raising efforts and charitable donations. I don't believe there is any government funding or assistance for this special emergency service. (The Scottish parliament does fund the Scottish Air Ambulance service directly, though).

Perhaps if you've got a charitably funded air ambulance covering YOUR area (list of UK air ambulances) and you haven't thought about this before (as I hadn't), you might consider making a donation or helping in fund raising in some way?

I should mention the Herts Air Ambulance and Thames Valley and Chiltern Air Ambulance, which also service areas where I regulary cycle.

Friday, 12 February 2010

Specialized Body Geometry Footbeds and Shims

I have long been a fan of adding orthotics to my cycling shoes.

Our legs are 'designed' for walking, not for cycling. The natural canting of the foot (present in most people) helps to make walking very efficient, but while pedaling a bike, it can make the knee move from side to side (or rotate). This is inefficient and can sometimes cause repetition type injuries to ankles, knees and hips. Orthotics specifically designed for cycling, generally footbeds and shims, can be added to shoes to correct this problem.

I firmly believe that having a biomechanically efficient alignment between my pedals and shoes and my feet, knees and hips, improves my cycling and reduces my cycling related injuries.

Specialized BG Tahoe MTB Shoes, Footbeds and Shims

I've used Cyclefit in London a couple of times in the past for their racing shoe fitting service to achieve this. (I've also had an excellent bike fitting done there too).

Their shoe fitting service is quite involved and includes tests both off and on the bike. You are interviewed first about your cycling habits and then some biomechanical data and body measurements are taken. Footbeds and shims (if necessary) are added to each racing shoe based on the measurements and a static bike is used to assess the result. A laser sight line is pointed at each leg in turn to check the foot / knee / hip alignment and that the knee makes no side to side motion while pedaling. This is a great service and highly recommended, but it is expensive!

Since getting the Nomad, I've been using a pair of my 'tuned' racing shoes and a set of my normal road pedals, so that I could get used to the new bike position without disrupting my pedalling action. I also wasn't sure at the time, what I wanted to do about moving to a touring shoe setup and whether that would mean changing my pedal system as well. I'm pretty settled riding the Nomad now, so I decided to take a look at my shoe and pedal options...

Some more pictures (for shoe fetishists only...)

Of course, I was keen to set up any touring shoe I bought 'properly'. Riding across Canada would probably expose any biomechanical pedaling inefficiencies pretty quickly, especially as I'm used to pedaling 'properly'!

After a useful bit of forum researching, the Specialized Body Geometry system of shoes and footbeds jumped out at me. I decide to purchase the BG Tahoe MTB Shoe, a cycle touring shoe with good walking potential and the matching footbed and shim system. (Note that the footbeds and shims could be added to any cycling shoe, you don't need Specialized branded shoes).

I visited a Specialized Concept Store in Ruislip, West London, to try on shoe sizes and sort out the footbeds and shims I required. I was asked to stand on the Specialized "Arch-O-Meter", a thermal pad that measured the profile of my feet arches. I already knew that I had 'flat feet' and the "Arch-O-Meter" showed that impressively! That information enabled me to choose the most appropriate footbed profile (red or blue for me) and a selection of shims. While I was in the shop, I also picked up a pair of Mr. Shimano's (2nd) finest SPD pedals, the PD-M770 XT.

Shimano XT (PD-M770) SPD Pedal

Once home, I had more shoe setup data to gather! I needed to measure whether my forefeet were varus or valgus (or neutral). I already had a good idea that my feet were varus (as are about 85% of the population) from my Cyclefit shoe fittings. My right foot is also slightly more varus than my left foot!

The Specialized test involved performing 1/3 leg squats in front of a low mirror to simulate a pedalling action. You drop a plumb-line from the mirror and also mark a dot on your knee-cap. Then you line up your second toe, the dot on your knee and your hip with the plumb-line, perform the leg squat and observe the movement of the knee. For most people, this will result in the knee moving towards the centreline of the body. This indicates a varus forefoot. You perform the test separately for each leg.

You then repeat the test with the cycling shoes on. This time you're aiming to keep the knee in line with the plumb-line (and thus in line with your foot and hip). You achieve this by adding an appropriate shim (orange = varus = +1.5º, yellow = valgus = -1.5º), if required, to the inside of the each shoe, underneath the footbed. Zero, one or two shims may be needed. I ended up with one orange shim in each shoe!

So I'm now set up and ready to swap over my pedals and shoes. This should be interesting...

Tuesday, 9 February 2010

Thorn's Eccentric Bottom Bracket

I've adjusted the Raven Nomad's Eccentric Bottom Bracket (EBB) once so far, to re-tension my slightly elongated chain. It was a painless affair and took 2 minutes. I will have to do this about once every 1000 - 1500 km to maintain reasonable chain tension.

Although the first adjustments of the chain tension will be easy to perform, I'm not convinced (at the moment) that they will always be so. This is because of Thorn's choice of using a Set Screw EBB.

Thorn's Set Screw EBB

To lock the EBB after adjustment, you screw in two large semi-pointed set screws (bolts) underneath the bottom bracket. Once tightened, the set screws make indentations directly into the EBB casing enabling the screws to grip the EBB and keep it firmly in place. Every time you adjust a virgin EBB, you get two new (permanent) indentations. Over time, these indentations build up. I can think of some possible niggles with this method of locking the EBB.

Firstly, you will only be able to adjust the chain tension in quite coarse steps. If you try to make a very small adjustment, the set screws will engage the edge of the existing indentations and 'deflect' the EBB back to the previous position. (This has been mentioned on the Thorn forums). Not a big issue, but some people like to have a 'perfect' chain tension all the time and this is not achievable with a Set Screw EBB of this type.

Closeup of set screws underneath the bottom bracket

Once you've gone through one chain, you'll have a nice set of indentations in the EBB. When you fit a new chain, you'll need to reset the EBB. This should be pretty easy to do, as a new chain is of a standard pitch, so by naturally tensioning the chain you should 'find' the first EBB indentations again. After that, though, could it become more hit and miss? Unless you re-tension the chain at roughly the same slackness as the first chain (easy to judge?), the EBB will accumulate further indentations. Eventually, you could unintentionally deflect into existing indentations and move the EBB from your intended position. This might niggle if the deflection over-tensions the chain slightly, perhaps?

This could also happen if you use different combinations of chainrings and sprockets, on the same EBB, to develop different gear ratios (E.g. 40x16 and 38x16). Each ratio will require a different EBB starting position and probably, separate adjustment indentations.

Perhaps it's worth marking the outward face of the EBB, every time you adjust the chain tension, so that later at least you know where the existing indentations are?

There are other designs for an EBB. One design uses a split bottom bracket shell with 'pinch bolts' that clamp the shell around the EBB, rather like a brazed-on seat collar clamping a seat pin. Another (patented) design is the Bushnell Eccentric. Instead of using two set screws to lock the EBB, it has an allen key fitting, on the outward face of the EBB, which drives internal cams apart that spread the EBB inside the bottom bracket shell. Another similar design is the Carver EBB. The Gary Fisher EBB operates in a related way and looks like an oversized 'quill' stem! (Note, the Bushnell is 53.8mm in diameter and won't fit the current 51.3mm Thorn BB. The other 3rd-party examples probably won't fit either as Thorn's EBB seems smaller than 'standard').

The alternative designs certainly appear to offer a finer granularity of EBB adjustment and solve the potential niggles I've discussed, but perhaps introduce different compromises and problems? (I've read of some creaking and slipping issues).

What do people think? It would be interesting to know the underlying reason(s) why Thorn choose the older style Set Screw EBB ahead of other potential designs...

Wednesday, 3 February 2010

Raven Nomad Rack Mounting Bosses

In the advertising literature for the Raven Nomad S&S that I downloaded, Thorn made several statements about their rack mounting bosses being 6mm, highlighting, to me anyway, a clear advantage over standard 5mm bosses commonly found on other bikes.

They also have 6mm stainless steel bosses for our own heat-treated Cro-Mo carriers... The frames have ... oversize (6mm thread) upper carrier bosses... The forks have ... oversize 6mm stainless steel fittings for lo-loader carriers...
Raven Nomad Brochure Issue 2 May 2009

Although the literature was accurate in this respect, I thought it slightly misleading after I received my bike. I had assumed all the rack mounting bosses would be 6mm when in fact, the rack mounting bosses on the Raven Nomad rear dropout are actually 2 x 5mm.

Two x M5 Bosses on Raven Nomad rear dropout

My Thorn Expedition rack was fitted to the rear dropout with one M5 bolt and four padding washers per side. I was surprised by this. It could be argued that, of all the rack mounting points, this point will be under the most stress when hauling heavy loads!

After speaking to SJS Cycles, I gathered this was a legacy issue concerning Thorn's Rohloff specific OEM rear dropouts. The same dropouts are used across Thorn's entire Rohloff range, apparently because they are very expensive to manufacture. The current dropouts have two 5mm bosses for rack and mudguard fitting per side. I suppose it must be considered too costly to produce a separate 6mm bossed version for the heavy duty Raven Nomad?

SJSC has some cast dropout adaptors that convert the twin 5mm bosses into a single 6mm rack mounting point, but I was told these were mainly used to move the rack outwards to prevent fouling on disc braked equipped bikes. They don't usually fit the adaptor to bikes without disc brakes because to paraphase the SJSC contact I spoke to: "it's debatable whether it makes the rack fixing any stronger, as the rack legs have to be 'sprung' outwards to fit the adaptor".

 Cast End 2 x M5 to 1 x M6 Stainless Dropout Adaptors
(with 5mm lathe reduction of face)

I could also tap out one 5mm boss to 6mm per side (if I felt brave enough) as the bosses appeared to have enough surplus metal.

I was finding this 5mm boss 'compromise' a touch frustrating. Either you needed 6mm mounting points for 'expedition' racks on an 'expedition' tourer (as Thorn's Raven Nomad literature suggested) or you didn't!

So the options were:
  • Continue with 1 x M5 bolt + padding washers per side;
  • Fit the cast dropout adaptors;
  • Tap out a pair of 5mm bosses to 6mm.

 Adaptor secured with two M5 cap-headed bolts

After some um-ing and ah-ing, I decided to fit the cast dropout adaptors. (I was sent them free of charge by SJSC). Crude reasoning suggested it would be better to spread the rack load, at the rear dropouts, over four x M5 bolts rather than two. I assumed the M5 bolt would continue to be the structural weak link under this setup. I didn't feel comfortable tapping out the boss threads on the bike's dropouts.

Rack secured to the adaptor with M6 bolt

In light of my conversation with SJSC over the adaptor's primary usage and the fact that I didn't run disc brakes, I asked my brother (who works in precision engineering) to lathe 5mm from the adaptor's face. This reduced the adaptor's width from 15mm to 10mm and meant that the rack legs needed to be sprung outwards by a smaller amount when fitted.

Rack now sits 10mm away from rear dropout

I don't believe I've compromised the adaptor (!) as it's still thicker than the bike's dropout bosses and I'm content with the final result. Time will tell...

(There was some discussion on this subject in this thread on the Thorn Forums during September 2009).