Author Topic: Happy coincidence (Sherpa Mk2, Nomad Mk2 650B-capable)  (Read 7228 times)

Danneaux

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Happy coincidence (Sherpa Mk2, Nomad Mk2 650B-capable)
« on: January 11, 2012, 10:34:37 PM »
Hi All,

My Sherpa is currently running 26x2.0 Schwalbe Duremes (47mm actual cross-section at middling pressures).  I did some measurements today and by happy chance, it appears the bike could take 650B rims with tires about 12.5mm narrower/lower in profile and still have the same clearances and nearly identical diameter.  Even the fenders would still fit without adjustment. BB clearance and overall handling should be unaffected to any significant degree.  650B rims are 584mm in diameter, while 26" rims are 559mm.  Divide the difference by two to get the radius, and the brakes only have to go upward 12.5mm.  The way my bosses are fitted, the brake pads are mounted very near the bottom of my Deore v-brakes, and there is a bit more than 12.5mm clearance to move them upward to reach a taller rim.  Since most tires vary in cross section/profile at a nearly 1:1 ratio, if one is running nominal 26x2.0 (~50mm) tires, then a 650B tire about 12.5mm narrower/lower in profile should fit identically.  That would allow use of many of the Grand Bois tires (a 650B x 38mm Grand Bois Lierre would be about spot-on for a direct replacement).  It is possible a 42mm Hetre might fit, but I'd want to try it first.  Lots of the narrower/lower profile 650Bs would fit, but the change in pneumatic trail due to the lower profile would alter handling to a degree.

For those wishing for a change, the 650B conversion might do the trick.

I love the near-universal availability of 26" tires and rims, and I am very happy with my 2.0 Duremes; I flew along at 20mph/32kph on them yesterday and marveled at how quick they were for a fat tire.  In contrast, after being the French Touring Standard back in the day, 650B nearly died out completely for many years, and are only now becoming available in the US, Europe and Japan in what can only be seen as limited quantities compared to 700C and 26" offerings.  Still, for many 650B is the Golden Mean between the two more common sizes, and the converted muse rapturously on their fine-riding qualities.

This is all conjecture based on calculation and measurement by me, but it is encouraging to think we might have yet another option for rolling stock on these versatile bikes.  It might also hold true for the Ravens and other Thorns -- measure your brake reach to see!

[1 September 2012 EDIT: Not only was my 2011 560S Mk 2 Sherpa 650B-capable, but so is my 2012 590M Nomad Mk2, thanks to even greater frame crown/bridge clearance and identical adjustment range in brake-pad reach. This opens up some real possibilities in terms of future wheel/tire choice, as this size is poised to explode on the market once again as a rough-service/MTB tire and extend its reach as a randonneur tire in 2012/2013. Every major manufacturer is introducing models using this wheel size at the time of this writing, and the Grand Bois 38mm Lierre randonneur tire would be the same overall diameter (within 1mm) as a 26 x 2.0 Schwalbe Dureme, giving identical geometry when used in place of a 26x2.0 tire on the Nomad. The Nomad Mk2 has generous tire clearances, and I believe it could easily accommodate larger 42mm Hetres, but at a slight change in geometry resulting in a bit more trail. See: http://www.thorncycles.co.uk/forums/index.php?topic=4245.msg19567#msg19567 Be sure to check the brake reach on your own frames to confirm the pads will reach upward another 12.5mm from their present setting, and check tire radii to make sure there is crown/bridge clearance with and without fenders to know for sure if this switch would work for you.]

Best,

Dan.
« Last Edit: September 01, 2012, 08:58:38 PM by Danneaux »

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #1 on: January 18, 2012, 09:23:38 AM »
Interesting observation Dan, however since the availability of 650B tyres in the UK is as rare as hen's teeth I don't think I would explore this option.  OK you can get them online, albeit with very limited choice; but if you had a significant tyre failure out on the road it is extremely unlikely you could pick up a replacement tyre from any LBS if you were away from home - you would need to carry a spare tyre at all times.

As far as I can tell from some bike blogs I have looked at the 650B is increasing in popularity with randonneurs in the USA, but I am a big fan of 700c which I find much faster than 26" and would not see much point in splitting the difference.  I also find it curious that most examples of this size I have seen seems to coincide with the deployment of HUGE bar bags and no saddle bags - this makes me think these bicycle owners have a very different outlook to me (each to their own I guess).

It seems to me that tyre options for road going bicycles seems to be increasingly polarising to 700c.  Virtually all of the current models of 'hybrids' from the major mass producers (on sale in the UK) seem to have migrated from 26" to 700c.  The alleged demise of the RST and the release of the new 700c Mercury could indicate a similar shift by Thorn?

Given the increasing availability of cross type bikes with 700c tyres and disc brakes enabling excellent braking with drop bars and fatter tyres, I think that is the direction I would take if I were contemplating a new bike at the moment.  Mercury fits the bill here as well.

P.S.  One could also speculate that the increasing popularity of 29er (i.e. 700c) tyres and 29er MTBs could also affect the availability of 26" wheels.
« Last Edit: January 18, 2012, 10:47:29 AM by Relayer »

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #2 on: January 18, 2012, 09:02:53 PM »
Hi Relayer,

I'm so glad someone jumped on this topic, and I can cut to the chase and say I agree with everything you have said and stated so well.  What follows is the longer version...

I don't buy new bikes often, but when I do, it seems I always come in at the tail end of things simply by waiting so long.  Bicycling has always been viewed a little differently on this side of the pond than it has in the UK or Europe.  I think the bicycle has not been as widely accepted as a societally-integrated form of transport here, in the modern era, because of a) the typically vast distances in the US and lack of village-model community development, b) urban sprawl, and c) because a) and b) contributed to the widespread use of the automobile and an infrastructure that supports it, rather than cycling.  We also lack inter-urban mass transit.  The buses or subways may run in the cities and towns, but they typically don't connect towns.  The national rail system is largely in ruins, which is a shame; rail cannot be matched for per-wheel efficiency in the ground transport of goods.

In my view, the vast majority of people here in my lifetime (I'm 51) have tended to view bicycles as either toys, sports/fitness equipment, or expensive toys as sports/fitness equipment, in much the same way skiing or tennis went from human-centered pursuits to equipment-driven, with costs to match.  We seem to be headed more and more in that direction.  There's the Wal-Mart Specials for <USD$200-$300 and then there's a gap till the LBS bikes at around $800-$4,000, followed by a much larger gap that is filled by the truly high-end full-on customs by independent one-man builders where the frames seem to start at about $1,800 and go quickly skyward from there.  There's a few exceptions -- I did see a Giant TCR Advanced SL 0 advertised north of USD$10,000 at a LBS up the Valley from me.

When I started cycling "with intent" (sounds less pretentious than "cycling seriously") in 1977 as physiotherapy for car-accident injuries, it was almost impossible to buy a fully-equipped touring bicycle from any dealer in the country.  Despite Bikecentennial being in full swing (an effort to make transcontinental touring possible by linking rural roads...part of the nation's bicentennial celebration of independence), there weren't bikes ready-made for the purpose. People riding through Eugene had a terrible time with broken spokes and if you saw a cyclist by the roadside, you'd also see the tell-tale sag of a derailed chain.  Racing bikes had become the model to emulate, and manufacturers produced "10-speeds" by the bucketful, simultaneously creating and satisfying demand.  Despite most having the equivalent of gas-pipe frames, nearly every one was a stripped-down edition -- no fenders, no racks, steel corrugated-sidewall rims with Maes-bend drop handlebars and those horrid "safety levers" to keep us allegedly "safe".  At the time, tubular sew-ups were racing gear, and those used 700C rims.  Clinchers evolved here as alternatives for training and offered the convenience of quicker and easier flat repair without the worry of sewing and gluing.  Except for some truly horrendous lumps of massive, dead, quick-rot rubber labeled "balloon tires", every other tire for the mass-market came in 27".  Through 1984, my really nice Japanese touring bikes were built for and came with those 27-inchers, the Touring Standard.

The only bicycle I can remember from that era that came equipped with a steel-rod rear rack and alu fenders was one model Peugeot. It even came with Soubitez sidewall generator lighting. And, of course, it looked like a tank compared to the lithe, racing-oriented "10-speeds" sitting next to it in the floor displays. I remember one at a LBS that languished on the showroom floor for more than five years. A lot of dreck was rushed to the market to meet consumer demand. It wasn't until decent-quality bikes of the same basic design (Fuji, American Eagle, Nishiki, Maruishi, Miyata, Centurion) arrived from Japan that ridable stuff became widely available here on the West Coast. Better quality-control on the Asian bikes was reflected not only in better frame materials and assembly; the suppliers and sub-contractors stepped up the game as well. Firms like Inoye Rubber Company (IRC) equipped the bikes with decent tires. Nylon skinwalls replaced what looked like burlap dipped in some sort of golden confection only loosely resembling "gum rubber" that immediately developed gaping cracks before the bikes left the showroom floor. Japanese production and imports really made a positive, quality difference in the midst of the so-called Bike Boom.  The Japanese manufacturers also had the production capacity and a favorable yen-dollar ratio to make their bikes appealing.

Custom-builder Bruce Gordon was the first domestic builder I knew personally to equip touring bikes with 700C tires, and he seemed like a nutter at the time, when 27" was the touring norm.  We spoke at length about it at his home-shop past the airport on Clear Lake Road and when he spoke to my touring classes at the university. As it happened, he was prescient beyond what anyone could see, and soon the selection of quality 27" tires was so poor, I had to switch to 700C myself (not an easy task, thanks to brake reach and such) just to get something that would hang together.  Unfortunately, we weren't quite there yet for touring, so those high-quality tires were all narrow, and suffered from label inflation.  Most of my touring through the '80s and well into the '90s was on tires labeled 700x28C, but were in fact only 24-25mm in cross-section. Marketing was still race-driven and truly wider tires suffered in the weight comparison when everyone sought ever lighter equipment. Gram-weenies ruled the day and the drillium craze came and went, only to be replaced by the Next Big Thing -- aero.  Cheat Gravity gave way to Cheat The Wind.  To protect the rims under touring loads and on rough roads, I hammered 125psi into my 1-inch skinwalls and they handled like rubber-coated rims, with no suspension or compliance. I found the only way to manage in gravel was to hover above the saddle and go like stink on a hot summer day -- fast as fast could be so I had some floatation on the loose stuff.  A bit like cyclo-cross, gravel-dirt-off-road touring involved a lot of dismounts and lifting.  Axles suffered, but Phil Wood saved the day with his oversized design and sealed cartridge bearings. Yay, Phil!

Then, when everyone was tired of being beaten to a pulp on bikes that were almost never really raced, the Mountain Bike Craze hit, parallel to the rise in SUV popularity. These bikes sat people upright so their hands and necks didn't hurt, and the wide tires meant they could be ridden into, over, and off curbs with nary a care.  The early mountain bikes were akin to the balloon-tires bikes of the '50s and '60s, but lighter, more rugged, and geared for easier pedaling.  Of course, they got better and lighter and faster with time, and finally eclipsed the sale of virtually every other sort of bicycle here in the States before exploiting every possible sub-category including downhill, cross-country, and whatever.  A horse for every course, even if there wasn't one -- just go out and hammer in the mud and dirt or ride to the local college/uni campus. They saturated the market as thoroughly as the 10-speeds of the bike-boom era.  When little kids drew pictures of bikes here in 'Merka, they drew Mountain Bikes, "the regular kind", not drop-bar road bikes and certainly not fully-equipped, pannier-laden world tourers and trekkers.

The US mass-market seems bifurcated between racing-oriented road bikes at one extreme and some flavor of mountain-bike at the other, and guess which one has taken on the role of all-'rounder?

Currently, there are a few dedicated, road-oriented 700C touring bikes in the US, but it seems to be more of a niche as far as the mass-market is concerned. Surly's Long Haul Trucker leads the pack by a wide margin and now comes in a variety of flavors including a 26-incher, trailed by the Trek 520 and more distantly by offerings from REI (Novara), Jamis and Fuji. Few-to-none of these bikes are pre-equipped with bottles, fenders, lighting, or tubular-steel racks; at most, they might include an aluminum rear rack and a bottle cage.  There really is nothing like the Sherpa; the 26" Surly is as close as we get, with a few exceptions.  To get a "complete solution" tourer means stepping up to a true custom, or equipping it yourself.  Lots of people own bicycles, but in terms of the larger population, very few actually ride regularly or commute. Despite some really wet weather, Portland and Eugene see comparatively large numbers, but compared to car drivers, it remains miniscule.  A recent PBS program on the topic referred to a figure no higher than 5% for bike-commuting nationwide. The overall average is far below that.

Oregon has become a hotbed of custom builders, and that extends up through Washington and down through California and across the nation.  Led by the custom-builders, 650B is seeing a resurgence, along with low-trail frame designs oriented around the huge handlebar bags you mentioned, Relayer.  I thought 650B tires had truly died out, never to be seen again, and now there is this resurgence among custom-built bikes here in the States.  Rivendell has embraced the size, and so have a number of others. The trouble is just as you've said, Relayer -- the infrastructure, supply chain, and availability just isn't there.  It is virtually impossible to stop at some rural US shop and get an in-stock 650B replacement.  It wasn't till this year I saw a 700C replacement tire (by the Slime tube-sealant company!) available at Wal-Mart, widely regarded as the nation's largest discount retailer.  Till now, it has always been low-quality 27" or 26", with the latter being dominant and only available in a knobby, lugged tread.

650Bs do split the difference between 27"/700C and 26" in size, and I can see they might ride well, perhaps even be the Golden Mean their proponents claim. Unfortunately, as someone who has seen fads come and go and some really nice bikes (including older European-built 650Bs individually imported to the States by individuals back in the late-'60s-'70s) obsoleted by the lack/unavailability of good tires, it seems a bit like the Next Big Thing all over again, a way to differentiate product in a market where profit margins are notoriously low.  

I think 650B is a movement and tire size that at present favors custom-builders, who can create frames with the proper clearances and with geometry optimized for the tires.  There is also an element of nostalgia driving the process, and some of the results are exquisite, as if Rene' Herse or Alex Singer had come to life and produced frames anew.  Boulder's come to mind, among others.  I have one that resembles these, a 1980 Centurion ProTour I promptly turned into a 700C, Japanese-component-equipped version of a 1948 Herse Le Campeur (pic).  Still have it, but it isn't suited for expedition touring.  Tubing and geometry are all wrong, and the platform I started with is so stiff and upright, it beats the snot out of me on rough roads.  I get off the bike feeling as if I'd been dragged behind a truck, achey and not at peace.  No, looking the part is not enough, and these 650B builders are at least turning out Complete Solutions, thanks largely to the tire size and resultant geometry needed to accommodate them.  They are tapping into a market; in this case, randonneuring.  The trouble is, it is a niche market for builders and buyers at present, a "high-E" market, to borrow a term from Grant Petersen -- a market that requires a lot of Education and Explanation to make appealing, one whose benefits aren't immediately clear and one of degree rather than magnitude.  Apart from this niche cognoscenti, the larger public has no idea what a 650B is or why it might be better, though the InterWeb is helping.  As for "better", the margins are pretty slim and open to wide interpretation and discussion.  Such things are troll-bait and I have no desire to ignite a flame-war.  This little essay is just a putting of thoughts to paper and I type really, really fast, as some of you have suspected.

I mentioned nostalgia as part of this.  I think the 650B movement we're seeing here in the US is in part a reaction to the shortcomings in current market offerings, coupled with a recognition that a lot of the European custom touring-bike makers in the pre-/post-WWII era had some genuinely innovative solutions that also genuinely worked...and then were abandoned as the market changed.  There is a desire to recapture that time when complete, purpose-built machines were more readily available and worked far better than the stuff that (never fully) replaced them, and never existed here.  There is a valid point in there.  There's also marketing reality and the fickleness of a market-driven buying public who is motivated more by a desire for New and a perception that New Is Better Because It Is New.  When one thinks about it, that's why 650B fell from favor the first time.  It was replaced by other sizes.  Now, what's old is new again, at least from my perspective.

The trouble is, for use away from a mail-order resupply of tires and tubes, how are the rider/owners going to manage?  It's hard enough to get 650B tires here without taking some extra steps and going either mail-order or having a sympathetically-aligned LBS.  How would one manage past our borders?  Take some with you, I guess, as most global tourists (and I) do.  The thing is, 650B tires have not yet hit a point of critical mass in the mass-market, at least not here.  Less so elsewhere, I would imagine.  When I was at uni, a friend from Japan had to wait months for a replacement 650B tire for his custom-built Toei.  It was a special-order French Wolber, and took forever to reach the shop in 1982.  It's a bit better now thanks to QBP (Quality Bicycle Products) and  the 'Net, but a lot of shops still don't stock them.  Only one of our (newer) local shops here in Eugene regularly carries Schwalbes, and they rarely have 26" Duremes in my size.  Good luck finding a 650b Grand Bois, Pari-Moto, or Hetre at Wal-Mart or in-stock at a small town's corner shop.  As part of a well-engineered bicycle, I think 650B can also work well.  It just isn't widely available and is still a long way from being a standard. Both those qualities make it impractical at present for world tourists and (it seems) for those away from a US or Japanese supply chain (despite the French-sounding names, the major 650B tires available here are made in Japan).  There's easier, existing alternatives in 700C and 26"; mostly the latter for tourists.  So far, 650B doesn't feel enough different from either of those to have really caught on.  Andre Jute, our esteemed fellow forum member, has made a cogent argument on his website/blog showing how "29er" tires are the worst of all worlds, subverting the best qualities of 700C and true balloon tires to embody the worst of each.

When I selected the Sherpa, I hoped I was coming down on the right side of changing and evolving standards.  I wanted a bike "future-proof" for the next 20 years, knowing from the outset how impossible that is.  My 9-speed Deore drivetrain was replaced on the market by Shimano's 10-speed version while the bike was still on-order (9-sp still appears more practical and long-lived for my use, but I was perfectly happy with my 7-speed half-step on the '89 Miyata 1000LT, so there ya go).  The threadless steerer/headset has been a joy in allowing me to decorate it as I wished with a whole slew of accessories impossible otherwise, and it allows service with just a 5mm allen instead of one or two huge spanners.  The Hollowtech II external-bearing BB is appealing now the earlier problems with bearing life and sealing have been largely addressed (and Phil Wood has replacements available) and is backwards-compatible with square-taper and old cranks in a pinch.  I made sure my 9-speed bar-ends had a friction option, and so did Thorn when equipping it.  I'm late to the 26" party, but they are still the best bet for worldwide availability.  

But will it all last?  Likely not.  I hear increasing rumblings regarding a variety of new BB shell diameters, all larger than what I'm running now.  Will those frames be backward-compatible?  If not and the market goes that way, will we ever be able to get square-taper, Octalink (it's already going-to-gone in some flavors), and Hollowtech II (what happened to Hollowtech I?...oh, that's right...there were fretting issues with counter-loading of pedals till Shimano corrected their design for people who lead when coasting with the off-foot).

I started a Muppets Thread topic on this last Fall, asking for prognostications for the future of cycling ( http://www.thorncycles.co.uk/forums/index.php?topic=3786.0 ) and I guess this is part of that for me.  Yes, Relayer, the market is changing and we'll see more as time goes by.  Already, the horizontal diamond frame has given way to sloping top tubes, and composites and hydroforming will change them further.  I agree we'll see market ever more polarized at the extremes, and we're seeing it even now in the RST-->Mercury shift.

Hopefully, 26" will remain the most popularly and widely-available touring/trekking tire for awhile and I (and others like me) will be fine.  Just the same, it's nice to think my happy little Sherpa might have another option "just in case".  I'll take every advantage I can to keep my bikes on the road, especially one as nice and beloved as my new Sherpa.

All the best,

Dan.
« Last Edit: January 22, 2012, 09:55:46 AM by Danneaux »

Relayer

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #3 on: January 19, 2012, 11:33:19 AM »
Dan

What a wonderful piece, your knowledge and insight into bicycles past, present, and even future is immense!

Like you I am fairly new to the 26" party, but unlike you I think I jumped in on a more trial and error basis as opposed to your meticulous planning methodology.  I have learned a lot since I got my RST and am now much more settled with this bike, the memories of my beloved Dawes Galaxy [gone to a new owner] still lurks in the background, but perhaps not so prominently as before.  However, the happy chance that you discovered the 650B compatibility gives a nice reassurance that we can all learn through an element of trial and error and even happy coincidences which we can share here... yes this is a truly great forum.

Now, must try to find Andre's piece on 29er tyres, to learn what new follies the fashionistas are leading us towards ...

triaesthete

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #4 on: January 19, 2012, 01:34:04 PM »
Hi Dan
that was a very interesting piece. I like the E market idea. It would seem to encapsulate most of the concept and activity of Thorn and Rohloff as well.
Thanks
Ian

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #5 on: January 19, 2012, 06:32:47 PM »
Here ya go...

Andre's take on 29ers:
http://coolmainpress.com/ajwriting/archives/1715

Yes!  This is a great forum, and I surely value the members.  I read posts here as a guest for some time before I formally joined or purchased, and the user experiences and loyalty helped tip the scales.  Imagine...buy a bike, get a community -- marvelous!   :D

All the best,

Dan.

JimK

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #6 on: January 19, 2012, 08:44:34 PM »
But will it all last?  
I find these issues totally fascinating. I worked a couple decades in the semiconductor industry, working with circuit design data. There is a giant heap of software involved in designing chip circuitry. The design data gets recorded in all different sorts of formats, with delightfully subtle interpretation issues everywhere. Ha! Just programming. Look at a crazy programming language like C++! Which exact version of the compiler and linker is required to get this program to work?

A few years ago we bought some real junk bicycles through Craig's List. The tires were rotten so I went to replace them. Wow! That was eye opening! One bike needed 590 diameter tires... the other needed 597 diameter tires. BikeTiresDirect is a good place to shop if you ever find yourself in such a situation. The LBS around here told me that these are basically disposable bikes, where there is no expectation that anyone will ever replace a tire.

My 1996 Trek 520 has a 7 sprocket cluster... not easy finding replacement parts for that, either!

I get a bit into the world of fountain pens, too. Many fountain pens take ink in cartridges, and the cartridges come in a variety of standard dimensions that have to fit the pen. There are some strange defunct sizes out there & it really doesn't pay to buy a pen that requires one of those, unless you just want to admire it rather than write with it!

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #7 on: February 08, 2012, 04:01:20 AM »
It looks like 650B may be poised for a comeback as the Next Big Thing...all over again.  See: http://www.bicycleretailer.com/news/newsDetail/6462.html

A lot of big names are on-board producing rims, forks and even complete bicycles for the 650B market-- SRAM, White Brothers, X-Fusion, and Fox sus-forks, DT Swiss, Velocity, and Sun-Ringle rims, Jamis, KHS.

Best,

Dan.
« Last Edit: February 08, 2012, 09:55:20 PM by Danneaux »

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #8 on: June 07, 2012, 09:50:48 PM »
A return of the 650B tire/wheel size is coming ever closer (toldya!  ;) ). For a really nice summary of the players and issues involved, as well as a full explanation of what this will mean for our bicycles and any we may choose in future, as well as parts/tire availability, See:
http://www.bikerumor.com/2012/06/06/whats-driving-the-650b-explosion-interviews-tech-breakdown-more/

Additional related Schwalbe news here:
http://www.bikerumor.com/2012/06/06/2013-schwalbe-tires-full-29er-650b-mtb-enduro-offerings-new-ultremo-road-tubeless-more/

Best,

Dan.

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #9 on: June 08, 2012, 04:44:03 AM »
Hi All,

For those interested in the hows and whys of a tire size we'll soon be hearing much more about (again), a nice timeline for the reintroduction of 650B wheels/tires appears here:
http://reviews.mtbr.com/650b-bike

Best,

Dan.

jags

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #10 on: June 08, 2012, 12:35:50 PM »
Dan will these new wheels fit my sherpa will the brakes work in line with the rim and at the end of the day are they going to be a whole lot better than what i'm riding at the moment.

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #11 on: June 08, 2012, 04:04:05 PM »
Hi jags! You asked some good questions, starting with...
Quote
Dan will these new wheels fit my sherpa
Maybe, if the clearances are right and the brake pads have enough upward clearance to reach.
Quote
...will the brakes work in line with the rim...
The brakes only have to go upward 12.5mm.  The way my bosses are fitted, the brake pads are mounted very near the bottom of my Deore v-brakes, and there is a bit more than 12.5mm clearance to move them upward to reach a taller rim. Mine will reach, but I'm running v-brakes and have a 560S frame. You have a different-size frame (perhaps the brake posts are in a different place) and are running cantilevers, so you'd have to take some measurements.

To see if your Sherpa would be able to take 650B wheels, check to see if there is 12.5mm of upward pad movement available at your brakes. Canti pad-adjustment slots tend to be a bit shorter than v-brakes slots, so this may be iffy. If you don't have enough room to move the pads that high, some other brands of cantis have more room (unless you go with a pull adapter, v-brakes aren't compatible with your STi brifters). The Tektro CR-720 cantilevers have a lot of vertical adjustment and use vi-brake pads with spherical adjusting washers to easily set toe-in. I don't have a pair at-hand to measure, but they might work if your present set is short.
Quote
...and at the end of the day are they going to be a whole lot better than what i'm riding at the moment.
Well...no! They won't be much if any different, most likely. I realize you're running narrower-width 26" tires than I am, but as an example, to equal the outside diameter of my 26x2.0 tires (Schwalbe Duremes), I would need to run 650x38B tires (within 1mm of the same outside diameter). The tire of choice to do that at present would be the 650B x 38mm Grand Bois Lierre.

I still truly believe (at present, anyway) the 26" wheel/tire is superior for touring because of greater availability of replacement tires, especially in remote areas. The replacement might not be ideal, but it would surely keep you rolling. The (reintroduced and about to become more widespread) 650B is at present very rare in local bike shops just about everywhere. Even if that changed, it's not going to make a big difference to your ride if the outside diameter is the same (and likely weight; the 650B x 38mm tire isn't a lot lighter than some 26 x 2.0 examples, and the 650 rim is larger and the spokes longer. Weight might well be a wash). For your needs (and your stated desire for lighter wheels), I think you'd be better off or about the same going for a set of narrow, lighter 26" road slicks on light 26" wheels than to spend all the money for a 650B setup.

650B is a nice wheel size, coming as it does midway between 26" and 700C, and I'm not disparaging it in any way; it did used to be the touring standard on French bikes for very good reason. However, if you already have a nice set of trekking/touring wheels in 26", I see no need to deliberately switch. If your bike is made with clearances that allow the use of either, then you're all set "just in case" things go overwhelmingly that way (and I've seen it happen in the States when 700C supplanted 27" on road-touring bikes).

I am just hoping to keep Sherpa running in the years to come, and have lived through previous fads that rendered my previous favorite tires unavailable (there used to be a huge choice in 27" touring tires...even nice road slicks in that diameter [Avocet]). This is a way to sell more bikes, it is a size that will come, and likely go (again) with time. However, we'll soon see it bandied about widely in the bicycle press and on the showroom floors, and I can see a possibility road/touring oriented 26" tires could become hard to find at some point (the knobby MTB tires will likely live on for a long time).

It's just nice to think that if needed, it might be possible to carry on and keep a (by then) old frame going and on the road. All that's really needed is brakes that will allow the pads to move 12.5mm upward in their adjustment slots. And new spokes, rims, tires, and tubes, of course. <-- That'll make sellers and manufacturers very happy, indeed. It's the Next Big Thing, all over again. These cycles tend to wax and wane and this one is on the rise.

Best,

Dan.

jags

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #12 on: June 08, 2012, 05:43:39 PM »
no adjustment on my canti brakes (PAUL)  ah i'll stick with what i have  but myself some of those bios slicks in 26 that will do for me.
thanks Dan your a mind of information  ;)
btw it's my birthday today  ;D ;D

Danneaux

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #13 on: June 08, 2012, 05:45:49 PM »
Quote
...it's my birthday today
Well! Happy Birthday, jags, and very best wishes. This is the start of your own personal New Year! May it be filled with joy, happiness, and the satisfaction of a life well-lived. All blessings upon you!

All the best,

Dan.
« Last Edit: June 08, 2012, 05:47:49 PM by Danneaux »

jags

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Re: Happy coincidence (Sherpa 650B-capable?)
« Reply #14 on: June 16, 2012, 05:57:37 PM »
thanks dan only just seen this  ;D
very best of luck on your epic upcoming tour.
and also well done  Thorn on promoting DAN  to moderator.