Second in a series on bottom brackets. Numero uno is here.
The newest (2012) Long Haul Trucker complete bikes come with the Shimano UN55 square taper bottom bracket which is an improvement over the UN-P.O.S. used in earlier years, but when asked what I might upgrade on a stock Long Haul Trucker I am likely to recommend a new bottom bracket. Don’t get me wrong, the bottom bracket that comes standard on the stock LHT is perfectly adequate. But there are bottom brackets that will last longer.
With bottom brackets, one gets what one pays for. In this case more money buys better bearing seals, higher quality bearings made to stricter tolerances, and better materials throughout.
Phil Wood Company designs, manufactures and assembles precision bike parts in San Jose, CA. USA. Their bottom bracket uses two adjustable cups to hold the bearings and spindle in place which makes it possible to achieve the perfect chain line, since the bottom bracket can be positioned within a 5 mm band of “normal” centered position. The cartridge bearings are plainly visible when the unit is installed, which might make one wonder about the durability when used in extreme conditions, but Phil Wood Co. uses “seals which are as good or better than those found in the highest quality submersible motor and pump bearings”. I have only seen one Phil Wood bottom bracket that needed servicing though, and even that was straightforward….the unit can be sent back to the company for new bearings at a reasonable cost.
Phil Wood cartridge bottom bracketThe left and right cups use an interference fit with the bottom bracket and require the use of the Phil Wood bottom bracket tool
SKF is a German company (Correction: Thomas K. correctly points out that SKF headquarters are in Gothenburg, Sweden) which has been a leader in bearing technology since 1907 and today is the largest bearing company in the world. Their approach to bottom bracket design strives to incorporate the best of old and modern technology. Rather than using cartridge bearings pressed onto the spindle and into the bottom bracket cartridge they use bearings which are received by races which are part of the spindle and the shell. Custom seals are used to keep contaminants away from the assembly. This way they can use roller bearings on the drive side and over-sized bearings on the non-drive side increasing durability and strength. This design has some appeal to the retro-grouchy Bike Hermit, and SKF is proud of it too….they offer a 10 year or 65,000 mile warranty (just be sure to keep track of your miles) 😉
SKF bottom bracket. The little bit of bling afforded by the red cup is not undesirable.
The mechanical seal designed to keep the bearings cozy and happy in the most inclement weather
At the risk of talking down to some readers and over the head of others I feel the need to explain the term “bottom bracket”. According to Sheldon Brown’s Bicycle Glossary a bottom bracket is: The part of the frame around which the pedal cranks revolve, also the bearings and axle assembly that runs through the bottom bracket shell of the frame. This is an SKF brand bottom bracket. The red cup slips off to allow the unit to be threaded into the bottom bracket shell.
Looking at the late Mr. Brown’s page I realized I am opening a bona fide can of worms. There are several bottom bracket “standards”, and bottom bracket/crankset interfaces. We won’t even get into “outboard bearing” and “BB30” and other new standards which are mostly calculated to keep the buying public buying, while claiming to add some performance advantage…not performance related to the durability or function of the piece… but of the rider/bike.
“Square taper” bottom brackets are made to work with “square taper” cranksets and cranksets with suitable chain ring sizes for touring generally are of the square taper variety. Clink this link for a discussion of gears and gearing. So this series of pieces will be about square taper bottom brackets.There are still compatibility issues to think about though. The taper on Italian (Campagnolo) cranks and bottom brackets are different from the taper on cranks and bottom brackets made anyplace else in the known Universe, which actually is typical of Campy parts. And bottom brackets come with different spindle lengths. The correct spindle length for a given bicycle will be a function of the width of the bottom bracket shell, the shape of the chain stays and of the shape of the crank. For example: with a Sugino XD500 (XD2) triple crank set on a Surly Long Haul Trucker, a 107mm to 110mm spindle length works well.
Before the widespread use of cartridge bearings, bottom brackets were designed with loose balls or caged balls running on races inside the cups and races shaped into the spindle. Mechanical seals or o-rings were used to keep out water and dirt. Nowadays the spindle is held inside a case by means of sealed cartridge bearings pressed onto the spindle. The only seals being those on the bearings themselves. A less than ideal state of affairs for the part of the bicycle in a location that will be sprayed from time to time with a slurry of water, grease, oil, de-icer, sand and grit.
So, what’s the dyed-in-the-wool bike tourist to do? In the following posts we will explore some of the available options for touring bike bottom brackets. If the idea of reading about that titillates you, you should think about getting a life.
We travel, in a week, to the high desert south of Boise for a three day ride on mostly unpaved roads. For the rough, loose surfaces we have outfitted our bikes with wider tires. More air volume at lower pressures is going to make for a smoother ride and a wide footprint will float over the loose sections.
On the Long Haul Trucker I am running the Schwalbe Big Apple 29 x 2 tires. I have always been impressed with the way the Big Apple tires transform the ride on any bike and I’m looking forward to this test of their toughness.
Sky King will be riding the Grand Bois Hetre tires from Compass Bicycles. So far she is liking the way the Hetres perform on her 650b Rivendell Bleriot.
Julie opted for the Schwalbe Marathon Mondial in 26 x 2. The beefiest tire of the three the Mondial also has a more aggressive tread pattern. Left to right: Schwalbe Big Apple, Grand Bois Hetre, Schwalbe Marathon Mondial\ Tableau of Thickset Treads Sky King and Sky putting the Grand Bois Hetres through the paces. A rare Bike Hermit sighting
Notice that none of the bikes have fenders. We removed them because, even on the Surlys where “fatties fit fine” there was no room for fenders with the new big tires. And anyway, after my experience with tumbleweeds on my recent two day trip down to Swan Falls, I might infer fenders to be dispensable and even unsuitable for off road touring. Stay tuned for updates… same bat time, same bat station.
I recently changed handlebars on my A. Homer Hilsen. Going from the 48cm Dirt Drop bars to the same model in the 52cm width will hopefully provide a more natural position for my arms and give better stability for the loaded bike. The clamp bolt on one of the brake levers was somehow stripped or cross-threaded and seized in the clamp, necessitating the use of the handy Dremel tool to cut off the clamp. Busted The old, broken lever is on the left. In the foreground is the clamp which slips over the handlebar and is held in place with the bolt through the lever shown on the right
I decided to replace both brake levers with Tektro’s new TRP levers. Aesthetically, these might not be everybody’s cup of tea, especially this drilled out version. The levers themselves have a somewhat tortured looking shape and the hoods have the almost obscene protrusion of STI style brake hoods. But using these levers, it quickly becomes clear that this is a case of form following function. The long, flat hoods provide a comfortable platform for the hands and the shape of the levers fits the fingers naturally. Somehow the design even manages to provide more mechanical advantage – my side-pull brakes seem smoother, more responsive and more powerful. The flared out lower part of the levers are easy to grab either from the hoods or the drops. The silver button is a cable quick release. This optional plastic shim rotates the top of the lever for a flatter hood position. (I used it)
While I was at it, I decided to try to clean up the Brooks leather bar tape which had turned almost black from accrued hours of contact with my grubby mitts. I filled the sink with warm water and a little bit of dish detergent and lightly scrubbed the tape with a dish washing brush, rinsed it off and immediately installed it. Wrapping the bars with wet Brooks tape does a couple of things: it lets the tape stretch so that it wraps smoothly and when it dries out it conforms like a skin to the handlebars. A light coating of Brooks Proofide after the tape has dried completely adds back moisture and effulgence. This is the second or third time I have removed and re-applied this wrap, wetting it each time first, so, even though the Brooks leather tape is more expensive than other materials it is extremely durable. This tape started life as "honey" colored. This is after washing the tape and re-applying it. Washed and treated - Lustrous!
The Bike Hermit has a pair of MKS Unique pedals purchased in 1972 for the then princely sum of $25.00. The Mikashima Industrial Company, LTD in Japan has been making pedals since 1946 and is obviously doing something right. What follows is an overview of two of the dozens of pedal models the company offers today, the Sylvan Touring and the RMX Sneaker pedals. MKS Unique The MKS Sylvan Touring pedal is on the left, the MKS RMX Sneaker pedal is on the right The MKS Sylvan Touring pedal in front of the MKS RMX Sneaker pedal.
The RMX pedals weigh just under 400 grams for the pair. Same as the Sylvan Touring pedals. Both pedal models use a cone and loose ball bearing system so they are user serviceable. The Touring model has a larger diameter axle and larger ball bearings which may make it more durable than the RMX pedal. Removing the dust caps reveals the larger axle and bearings of the Touring model on the top.
Aside from the apparent difference in size and shape, there are some functional aspects to consider as well. The RMX Sneaker pedal, because of the way the cages are made, will not accept any sort of toe clips or straps, but the Sylvan Touring model will. Either traditional toeclips with straps or the Power Grip system will work. The Power Grip strap kit comes with all the pieces needed to bolt them onto a set of pedals. Pedals with flat sides to the cage and two bolt holes will accept the angled adapter plate which comes with the Power Grip Strap kit.
Some people prefer to not be attached to the pedal in any way, and they are entitled to their wrong headed opinions. (just kidding) For those people either the RMX or the Touring pedals will work. For those who want a little bit of added security and who, like the Bike Hermit, are not coordinated enough to keep their feet on the pedals in all conditions, the Sylvan Touring model with toeclips or Power grip straps would be a good choice. Based on past experience, either set of pedals should give years of dependable performance.
What makes a good wheelset for loaded bicycle touring? Durability will probably rate high in any list of desirable attributes. So, what makes a bicycle wheel durable? Rims:
An extruded aluminum double wall rim with a box section for strength. Drilled for 32 or 36 spokes with eyelets in the spoke holes. Eyelets can help distribute stresses and prevent galling of the metal where the spoke nipples rest. My personal favorite rims are Mavic CXP33 because they have a socket attached to the eyelet which distributes load to both walls of the rim. Another consideration when choosing a rim should be the width of the tire to be used. Schwalbe, the tire manufacturer addresses that on their website.
A double wall, box section rim. Photo from Wikipedia
Spokes:
Spokes are normally made of stainless steel and are of uniform thickness the entire length (straight gauge) or are swaged to be skinnier in the middle (double or triple butted). Counterintuitively, double butted spokes are a better choice for durable wheels for a number of reasons. The skinny part is made skinny by drawing that section of the spoke through a reducing die which increases it’s strength by work hardening. The swaged spoke is more elastic and absorbs the stresses in the mid section rather than concentrating it in the elbows and threads. The third advantage requires a discussion of lacing patterns.
A “3-cross” lacing pattern means that any one spoke will cross over three other spokes on it’s way from the rim to the hub. Actually it will cross over two and under one. Without going into a lot of detail (mostly because I would probably get it wrong) the stresses induced in a spoke when the wheel goes around under the rider and load are in that way shared by more spokes. Swaged or double butted spokes do a better job of sharing this stress than straight gauge spokes by their virtue of being more resilient – they flex more.
A 3-cross spoke pattern. Photo from Wikipedia
Hubs:
Hubs must carry the individual spokes and be strong enough for the combined force of all the spokes in a finished wheel, a force that can equal a half ton in a 36 spoke wheel. Hubs can use loose bearings or cartridge bearings with benefits and drawbacks to both. An oversize and/or steel axle can be stronger for load carrying than a smaller alloy axle. As a generalization, most manufacturers will turn to aluminum or other exotic materials in their quest for lightweight in the upper end range, so it might be better for the touring cyclist to actually buy the less expensive models if they use more robust and durable materials.
Wheels can fail from sudden loads, such as in a crash, or running into an immovable object, or from fatigue. Rims can be abraded by sand and road grit imbedded in the brake pads, and can eventually fail when the force of the inflated tire breaks the wall of the rim. Rear wheels carry more weight and receive more stress because of the rigidity of the rear triangle.
Most spokes will fail at the elbow where they enter the hub due to fatigue. A properly built and tensioned wheel laced in a three cross pattern can reduce the risk of fatigue failure.
Many new bikes come with original equipment wheels that look light and fast because they only have a few spokes and aerodynamic rims. However, semi-aerodynamic and aerodynamic wheelsets tend to be heavier than more traditional spoked wheelsets due to the extra shapings of the rims and spokes. More important, the rims must be heavier when there are fewer spokes, as the unsupported span between spokes is greater.
I borrowed heavily for this post from the book The Bicycle Wheel by Jobst Brandt. If you want more about the theory behind the spoked bicycle wheel and want to have a go at building your own wheels, this book is a must.
The late, great Sheldon Brown’s site is an encyclopedia of all thing bikey, and this page tells how to lace a wheel.
“Saving Your Butt, One ride at a Time” What a great tag line!
The saddle has a layer laminated to the underside for more support.
Customer feedback and diligent perusal of various on-line forums (somebody’s got to do it, the internet’s not going to read itself!) encouraged us to stock the Selle Anatomica saddles in the store. The saddles have a long cutout intended not only to relieve pressure but to allow the two sides of the saddle to move independently.
We have not had the chance to test these saddles but Selle An-Atomica claims there is no break in period. Here we compare and contrast the Selle An-Atomica Titanico and the Brooks B-17 Imperial:
The Brooks B-17 Imperial on the left, Selle An-Atomica Titanico on the right
The Selle An-Atomica on the left, Brooks B-17 on the right.
The Brooks B17 on the left, Selle An-Atomica on the right
The Selle An-Atomica nose bolt can be used to adjust the tension of the saddle and takes a 5 mm hex wrench. The bolt on the Brooks requires a special wrench, which is provided with the purchase of a saddle.
(Update 2/20/2012 – The Bike Touring News store now has the Schwalbe Marathon Mondial tires in stock in 700 x 35c and 700 x 40c sizes in the folding version. The 26 x 2″ folding tire is due to hit North America in March,2012.)
The new (2012) Schwalbe Marathon Mondial touring tire
The Schwalbe Marathon XR is frequently hailed as the best expedition/long lasting touring tire out there. The ‘XR’ was synonymous with ‘Schwalbe’, in fact, along with the regular Marathon, some think the XR helped build Schwalbe a good name and customer base. Unfortunately, in 2009 Schwalbe decided to discontinue the model. Other tires stepped in to fill the void, namely the Dureme and Extreme and the Plus Tour, but none of those had all the features that made the XR so popular.
Recently I read about a new tire- the Marathon Mondial. According to Sean at Schwalbe North America:
“……the Mondial is not a direct replacement to the Marathon XR, more of the next step in the evolution of the tire. Compared to the XR the Mondial will have the SnakeSkin sidewall which is an additional rubber coated aramid layer which helping to prevent sidewall cuts and abrasions. The Mondial also gets a modified triple rubber compound which we call TravelStar, the compound will increase road performance while also increasing the durability.” For more information I went to the global Schwalbe website and found this about the TravelStar compound: The Marathon Mondial has “State of the Art” TravelStar Triple Compound. Under the tread centre lies an elastic mixture for easy rolling, while there is a grippy rubber compound, for cornering traction on the tyre´s shoulder. In the middle of the tread an abrasion-resistant, harder compound offers low rolling resistance for thousands of miles.
Unpredictable gravel roads and potholes, acacia thorns: these are the treacherous tyre killers. Protection may come down to the smallest of margins such as the durability of the rubber mixture. The lightweight extremely densely woven High Density puncture protection belt reliably protects against punctures and ruptures. The light but sturdy “Snakeskin” protection provides maximum reinforcement against sharp objects that would otherwise cut the sidewall.
According to the catalog cuts I have seen, the folding version of this tire will have the TravelStar compound and the Snakeskin casing while the wire bead versions will have Schwalbe’s “Endurance” compound and their RaceGuard casing which is a double layer of nylon fabric.
Look for the folding tire in sizes 26×2, 26×2.15, 700×35 and 700×40. The wire bead tires will come in 26×2, 700×35 and 700×40 sizes. Availability in the US will be October 2011 for limited sizes and 2012 for the complete lineup. Prices will range from $48.00 to $90.00 depending on size and version.
This thread at crazyguyonabike gets a little out of hand, but in a good, funny way.
Just what is the best saddle for touring??? Drum Roll, please. The best saddle for touring is the saddle that fits your behind and allows you to ride in comfort!!
Chief out touring
Okay maybe that wasn’t the answer you were looking for, but it is the best we have to offer. No two people are shaped the same therefore no one saddle is going to be the end all saddle for every person.
The Bike Hermit used to tour on a Brooks B17, as to be expected, over time the saddle relaxed and had a bit of “splay” He punched holes in the sides (like the Brooks Imperial) and threaded the saddle with leather (from the Tandy leather store) and that solved the problem. About two years ago he switched to a Gilles Berthoud Aspin. This saddle was stiffer in the beginning and now has molded to his shape just perfectly. He easily has 3,000 miles on that saddle with no issues. Aha, you say, I will go research and purchase a Gilles Berthoud. Well, Sky King did her best to love the Gilles Berthoud Aspin spending hours adjusting height, position, angle etc but was never comfortable. Finally she measured her sit bones and realized between the shape and width of the Gilles Berthoud Aspin, it was never going to work for her. She went back to her older Fizik’s vitesse tri and problem solved. She is back to all day, day after day saddle comfort. She does plan to try the Brooks B17 Narrow as she misses not being able to carry her Zimbale 7 liter saddlebag but for now the Fizik’s Vitesse Tri is just fine.
Here are some very important things to consider when selecting a Saddle.
The Flyer does not narrow as quickly as the Zimbale
The width of the saddle across the widest area and how quickly it widens from the nose to the back will affect saddle comfort. Add to that the saddle position or the saddle tilt (nose down, nose up, nose level). Of course don’t forget to factor in the entire bike fit (see earlier posts)
Too Much Pear-Shape for your shape typically causes chafing in the inner neighborhood of the lower fold of the buttock, top-of-the-leg, panty line, hamstring attachment (however you want to describe it) because the saddle is too pear-shaped for the motion of your hip joints. If these are issues you have with your saddle, perhaps a T-Shaped style would work better. If you feel like you are sitting on a narrow, painful 2 X 4 a pear shaped saddle could be what you need.
Let’s get back to saddle width and length. The size of your hips or the size of your behind has very little to do with the size of your saddle, wide hips do not mean you need a wider saddle. The width between your “Ischial Tuberosities” ie) sit bones is what matters. Where those sit bones connect with your saddle makes the biggest impact in saddle comfort. Too wide or too narrow for your sit bones and the end result is pain and chafing. Sky King has a wider hip measurement than the Bike Hermit but he has a wider sit bone measurement.
Each saddle has “cheeks” on the wide back part. Sometimes the cheeks are even domed up a bit. Your sit bones are meant to land in the high part of that dome to take advantage of the padding and the overall architecture of the saddle. Saddle without domes still have a cheek area, the widest part of the saddle is where your sit bones should be resting. Measure the saddle from center of cheek to center of cheek. The saddle’s center-to-center should match the center to center measurement of your sit bones.
Next measure the saddle’s overall width. Generally the saddle’s overall width should be, at minimum, the same as the outside measurement of your sit bones OR slightly wider but NO more than 2 centimeters wider than the outside sit bone measurement. You want to be able to shift around to power up hills or use body-english around corners or just to give your butt a break, and STILL have the bones land on the saddle.
In the case of a many leather saddles your saddle must be about 2 cm wider than your outside sit bone measurement so you do not have bones contacting the metal cantle* plate.
(*rough description – the horseshoe shaped metal plate under the back of the saddle that holds the rails in place)
Measure your sit bones:
We could get all fancy and purchase memory foam or drop some dollars on a fancy gel seat specifically designed to measure sit bones and assist in determining the proper saddle width but we hate to spend money when things at hand will work just as well.
Three inexpensive options for measuring Sit Bones:
The Flour method
Take a gallon size zip lock bag, fill with enough flour for about a two inch flour cushion when the bag is lying on a flat surface. Place this bag on a hard flat surface – table or chair (we use a piano bench) Sit on the bag (preferably bare skin), mimic your bike position. Now stand up without disturbing the bag. Those two dimples/impressions in the flour are from your sit bones.
The Play Dough method
To make your dough:
One part salt, two parts flour, mix with water until it’s right for modeling.
Roll about an inch thick, cover with aluminum foil to keep it from being sticky, place dough w/ foil on a low bench, once again sit on dough (bare skin is best) and lean forward to approximate riding position since the sitbones become more narrow as you lean forward. Remove foil and allow to dry a little. The bones impression will become white first.
The Measurement
Take a millimeter tape measure and measure the impressions, recording your findings.
1. The inside edge to inside edge
2. Center of depression to center of depression, if easier, place a marble in each depression and measure the marbles.
3. Outside edge to outside edge
Center-to-center measurement correlates with the spot on a saddle that bears the weight of the sit bones. The saddle “cheeks”.
Outside to outside measurement is a consideration for some types of saddles, such as the Brooks that have metal rails, you do not want to have your sit bones resting on the metal rails. General rule of thumb – your saddle width should be about 2 centimeters wider than outside sit bone measurement. Again, you want your sit bones resting on the “checks” of the saddle and you want some wiggle room for movement as you are touring.
Inside to inside may be necessary if you plan to use a saddle with a cut out, to ensure the sit bones clear any large center cutout in the saddle. The inside bones falling into the ‘moat’ so to speak, causes a lot of pain in the bones surrounding the “soft tissue” area. To clear the cutout, you need about 20 mm extra space in between the inside distance of the sit bones. So, if the cutout is 60 mm, your inside distance is 80, then you have just enough clearance.
The Hand Method(s) of measuring
Sit on your hands, and feel for the two bones of your butt. They feel like elbows poking down into your hands.
Put the tip of your index fingers right under the part of the bones that is pushing hardest into the chair. (squish the very tip of your fingers between the chair and your sit bones)
Lift your butt from the chair leaving your hands on the chair, and have your assistant measure the distance between your fingertips. This is pretty much your center-to-center.
Then put your fingertips against the outsides of the bones. Push them right into the bones so they are on the outside of the bones. Lift your butt from the chair and have an assistant measure the distance between your fingertips. This is pretty much your outside.
Some people have sit bones that angle a lot from front to back. The “sits” are heavy thickened portions of the rami area of the pelvis and can have unique personalities of their own. You can measure again on the forward part of the heavy “elbow” bit if you can feel that yours have a definite angle. The forward portion of the heavy thick part of the bone is what your weight rests on more when you are in a more aero position. DON’T measure the thin blade like portion that is in your crotch, that is the rami and you do not want a saddle there. Measure from your backside.
Repeat your measurements a few times, average them out if you want.
You can also get these measurements by lying on your back with your knees to your chest holding a measuring tape and poking around for landmarks.
The Cutout
Cut Out on a Brooks B17 Imperial
Purchasing a saddle with a cut out can be beneficial if you have soft tissue pressure. An easy way to help determine if you might be a good candidate is to sit (commando or in thin underwear)on a very hard surface, feet flat on the floor, pedaling distance apart. Lean forward from the hips, keeping your back straight and place your elbows on your knees. If you soft tissue is feeling overly squished you may want to try a saddle with a cut out. Do some forum research, some people love them, other’s find the edges of the cut out equally irritating. Assuming you have a good bike fit and proper saddle height, consider adjusting the angle of your current saddle as well to see if that relieves soft tissue pressure.
Length
Years ago some saddle manufacturers started adding a short version to their line. Historically the short version came about for women riding in skirts and dresses, the longer nose would catch on the dress, making mounting and dismounting more challenging. Now a short version is more about personal comfort. Reading Forums and blog post about saddle fit there are numerous opinions about both. Sky King’s Fizik Vitesse Tri is a “woman’s” saddle but it isn’t any shorter in the nose than a Brooks Swallow.
Conclusion
We agree that finding the right saddle can be tough. Sometimes despite the best research, trial and error ends up being the answer. Taking your measurements and understanding your riding style are the beginning of your quest.
For more great info on choosing a Saddle read other blogs and forums. Sky King took the measuring suggestions from posts on the Team Estrogen Forum. Great resources can be found on sheldonbrown.com, team estrogen forums, bike forums (touring). Most of all don’t be afraid to ask questions. We both ride day in day out without saddle pain on two entirely different saddles.
The Bike Touring News store stocks two different versions of the Nitto Dirt Drop handlebar. The main difference between the two, or so I thought, is the diameter of the bar at the stem clamp sleeve. The RM-013 is 26.0mm and the RM-014 is 31.8 mm. I recently did a side by side comparison and was surprised to see just how different these bars are, not only in the clamp diameter but in the overall shape.
Nitto Rm-013 Dirt Drop bar (top) and the Nitto RM-014 Dirt Drop
The bars in the above photo are both 52’s. That means it is 52 cm from the center of the end of the tube on one side to the center of the end of the tube on the opposite side. Even though both bars are the same width at their widest, or the bottom of the flair, the top, flat part of the RM-014 begins curving to the drop much closer to the center of the handlebar, resulting in a narrower top section and a wider flare.
The Nitto RM-014 on the left, the RM-013 on the right
From the side the differences are not as pronounced. The bottom flared portion of the RM-014 on the left may be a slight bit longer and the bend a little bit sharper.
For a bike that will be ridden mainly off-road, the Rm-014 might be a good choice with the ramps at a little more of an angle (like in the last photo) and the brake levers mounted a little lower to make riding in the drops more comfortable.
But this picture I find to be the most interesting:
The 52 cm RM-013 is very similar to the 48 cm Nitto Noodle bar, it just flares out a little more and doesn’t have the slight return bend on the tops. A Google search revealed why. Grant Petersen from Rivendell designed both bars. The Dirt Drop was original equipment on the 1987 Bridgestone MB-1 and the Noodle was a replacement, with a few tweaks, for the Dirt Drop when Nitto stopped making them due to lack of a market. Now they are making the Dirt Drop again, in two versions. I personally like the extra flare on the RM-013 and I use them on my touring bike.
Either bar will accept bar end shifters and road style brake levers. The RM-014 is a few grams heavier in any given size and it comes in 50 amd 52 cm widths. The RM-013 comes in 46, 48 and 52 cm widths.
