Wednesday, September 8, 2010

Tubing and Wheel Size


One of the goals of the rSogn (reissued Sogn) is to reduce frameset weight. The rSogn would be available in three sizes: Small, Medium, and Large. These sizes would feature heat-treated Taiwanese tubing.

For the Small, the top and down tubes would be 7/4/7. The Medium would feature the same top tube, with a 8/5/8 down tube. Both the top and down tubes would be 8/5/8 for the Large. 

All top and down tubes would be 28.6 and 31.8 in diameter, respectively. Other parts of the frame and fork would be specified accordingly, with the stated goal of making the frame and fork as light as possible for a $600 frameset. 

Wheel Size

As we all can imagine, this topic could potentially determine the entire design direction of the rSogn. The requests for reissue received so far have been pretty much even between 650b and 700c.

As far as design and application are concerned, 650b is the ultimate wheel size. At the same time, 700c is readily available when it comes to small-block cyclocross tires, for example. Personally, I enjoy the benefits of the 650b size; however, I am still patiently awaiting a small-block 38c in this size.

To this end, I am fine with either 650b or 700c for the rSogn, and leave this up for discussion. 

Do share your thoughts and comments on these topics. 



Cody Larson said...

I vote 700c

Alex Wetmore said...

I would suggest using non-heat treated and smaller diameter 9/6/9 tubing instead. The ride quality and weight are nearly indistinguishable from the 7/4/7 that you've proposed, and the thicker tubing would be more robust when used offroad (not to mention less expensive). You could scale up to 10/7/10 on the larger sizes.

I built a frame very similar to the Sogn ( and uses 9/6/9 with a 28.6mm downtube and 25.4mm top tube for those reasons.

I do like that you are varying the tube weights by frame size.

I'd vote for copying the same tire clearance that the original Sogn had. Clearance for 650Bx60mm and 700Cx45mm is a very good combination that works for almost everybody.

I agree that a cyclocross-like 650B tire is missing. However the Quasi-Moto is a great tire, and is a good match for the original-Sogn.

This weekend I'll be riding ~100 miles on dirt roads on a friend's dSogn, and look forward to the experiences.

Phil said...

You mention three sizes (S,M & L), can you tell us what these relate to in CM? That would drive my wheelsize voting. I think I can trust much smarter people than myself to make calls on the tube sizing.

Anonymous said...

I'm with Alex on the tubing selection. I think it might give a more classic ride feel. Also very much 650 B. There are so many bikes in 26" and 700c for the small block. Build it and small block will come...

Would love canti braze ons positioned for 650B.


Jim G said...

+1 for everything that Alex wrote. Add both disk-brake mounts AND cantilever brake studs (with removable studs) positioned for 650B wheels. If folks want to run 700C wheels AND V-brakes, they can do what Gino did and use the Paul Components Moto-BMX brake to switch between 700C or 650B:

If you make this frame for 700C wheels, there will be too much overlap between it and the Drakkar, ATMO. I'd rather see an XO-1 style 26" frame before another 700C model.

Anonymous said...

Oops, forgot brake stuff is for a different day. Sorry.


Rob in Seattle said...

One of the things that drew me to the Sogn (after they were all gone!) was the flexibility of running different wheelsets. I'd vote for retaining that flexibility. It'd be great for me to be able to swap wheels between a Sogn and my 650B Saluki or my RB-T, in a pinch.

franklyn said...

I think the market space for this type of bike with 700c wheel is already well-covered by Salsa (Vaya, Fargo, and Casserole), Soma (Saga), Surly (Cross Check, Karate Monkey), Black Mountain, and even your drakkar. Ability to use 650bx55mm makes the Sogn unique (I realized I am one of very few people who only own 650b bikes; i have 3, including a M/L Sogn)

I wouldn't mind the Sogn keeping the versatility to use another size--700c in this case. Perhaps two sets of (screw-on) canti-post braze-ons (with only one set of posts); cantipost for 650b and disc mount.

I recently saw some adaptors that allow offsetting (either up or down) of screw-on cantiposts. I am not sure how well they work. If they work well, couldn't Rawland includes a set of those adaptors in the new Sogn shipment. One can then use 650b wheels (without adaptors), 700c (offsetting higher) and 26" (offsetting lower.

Jim G said...

Franklyn is talking about the Sinz Brake Post Extensions:

I think Tektro or Dimension offers a similar product, also.

Great idea!!!

Guitar Ted said...

Well, I'm going to weigh in with a bit different take......

Making a frame "versatile" is equal to making a frame "not excellent at any one thing" to my mind. I would say that the new Sogn should be either a strictly 700c bike, OR strictly a 650B bike. Making the bike work for both wheel sizes compromises weight, (for brakes- another discussion), geometry, and really, for sales in the end.

I would suggest that the new Sogn be something that isn't really available: A true wide tire road geometry bike. In this case, I agree with Sean that the lightest tubing possible be used. This shouldn't be confused with a mountain bike. Heavier, more robust tubing isn't what a bike like I am suggesting needs.

I'll save my brake thoughts for later, but to my mind, the vast quantities of 700c tire sizes available trumps 650B today. (Likely for the near future as well), so I would suggest a 700c tire size for this bike.

Sean mentions tires width, so I will also weigh in on that. I am only looking for clearance for up to a 42mm tire, 38mm with fenders for this bicycle.

Anonymous said...

I tend to agree with choose one or the other--how many times do you actually reverse your reversible vest? And if you designed the BB for 650B, you'd have to run skinny 700s anyway to keep the geometries close.

I think 650B is a better diameter for larger volume road tires, and there is a decent selection available. How many "wide" road tires do we really need? It's not like we need a selection of two dozen tread patterns. Really, it's a couple different widths and weights, maybe one or two treads for moderate trail conditions, at several price points. Already available in 650B.

700c, there are lots of bikes available. I run 37 Paselas on an old Nishiki. My hybrid Trek 730 takes 700c x 42. Newer frames include Crosscheck, Double Cross, etc. I know with 29er's you guys look for large volume low pressure as the holy grail, but again, for road, does 38 vs 42 in a 700c really make or break the experience? It would be nice to have a performance-oriented 650B option at under $700.


rperks said...

I think that the intent of the bike needs to be defined first. The original sogn was a very versitile bike that was built up many ways. As GT has said above the versitility can also be a hindrance. narrowing the focus can develop the product. If the bike is pushed into a 7oox42 max bike without 650b option sis it a sogn still? Is the Sogn a mountain/trail bike? or is it going to be a "road" bike this time around.

Without some design perameters you just end up with a possible hodgepodge and it may or may not be all that is hoped.

alex said...

I'd like a 650b production all rounder frame, I don't think there's any on the market anymore. There's a better selection of wide, high performance road tires in 650b compared to 700c. I really liked the looks of the Sogn when it came out, the same frame with lighter tubing would be fantastic.


Scott Gamble said...

I'm also interested in a wide-tire road geometry bike. A long-distance gravel grinder expedition bike. A 650b bike but with clearance for up to 700 x2.1's. I know, it's a weird strange desire.

I'm new to 650bs and like them a lot - but am concerned about the availability of these tires in areas that are NOT America. It's a personal concern I'll admit (I'm moving to Asia around New Years) but it's one that weighs in for me.

Most fatty wheeled compatible 700c bikes I'm familiar with (ahem CrossCheck and Long Haul Truckers) only provide clearance up to 1.9 in.

Other thoughts: Studded tires.

Nokian makes 700 x40 studded and 700 x2.1's. They have yet to make a decent studded 650b tire. The 650b A10 I'm told is a decent commuter tire for randoneuring bikes, but this isn't exactly a classic randoneuring bike.

Personally I run 2.1 Vulpines 11 months out of the year and love the poopin poop out of em; and I have a set of the 2.1 Nokian Extreme 294's for winter/ice riding too. If there was a way to reuse my existing 700c 29er wheels, boy that'd be pretty nice. I can't imagine I'm alone in feeling this way. There is a thin spot in the market between big wheeled cross bikes and small wheeled 29er bikes, and they hover in the 1.8in to 2.2in tire range it seems.

I don't know what sort of 650b gemoetry sacrifices would have to happen to provide this kind of compatibility, but with clearance for 700x 2.1's you'd provide the means for this bike to shoulder some of the more versatile smaller diameter 29er wheels out there which for some of us fit their own sweet spot.

I'm with Alex on the frame tubing.


orc said...

A 650 x {wide}b frame would be the best of both worlds; with a suitably adjustable brake, I could fit 700x{narrow}c wheels under the thing for summertime riding, then swap to 650x{wide}b wheels for mud, pebble, and/or snow.

Alex Wetmore said...

"I would suggest that the new Sogn be something that isn't really available: A true wide tire road geometry bike. In this case, I agree with Sean that the lightest tubing possible be used."

Sean and I aren't disagreeing in the tubing weight, I'm just offering a less expensive and more robust way of getting there.

A 7/4/7 28.6mm top tube has the same stiffness and roughly the same weight as a 9/6/9 25.4mm top tube. It is more fragile when dented (which makes it less suitable for using on rough roads in my mind). It needs to be heat treated, so it costs more. The same is true for downtubes.

9/6/9 28.6mm downtubes and 25.4mm top tubes give you Columbus SL or Reynolds 531 level tubing. It is not the oversized dead tubing of a Surly Pacer or Cross-Check.

I can fully understand Sean/Rawlands wanting to use 7/4/7 oversized tubing, just to make the bike more marketable.

I think of the Sogn as a rough stuff bike, good for road riding, dirt road riding, and light singletrack use.

Jim G said...

GT, can you pin down what you mean by "road geometry"?

If you're talking 700C wheels + 73/73 angles with good tire clearances, take a look at the Handsome Cycles Devil frameset. Rivendell, Salsa, and others offer similar products.

I'd really like to see Rawland offer a 650B frame again. I'm not sure what happened to cause the original Sogn to dwindle.

Stew said...

700c All the way.

C said...

+1 for both 650b and thicker/smaller diameter tubing.

Cody Larson said...

As for the thicker/ smaller diameter tubing: If this is to be a light weight, "performance" bicycle, a larger diameter of tubing would contribute to a stiffer frame at the BB and HT.

Pax said...

The heavier tubing used for the first go-round was the deal-breaker for me -it sounded way too similar to my oversized dead-riding rigid MTBs of yore.

So I'm happy to hear a lighter tube set is your first priority. As I'm no expert, I'll simply vote for "light as you can while keeping the price down".

I'd also like to vote for a 'versatile' 650b/700c wheel size please (aka: keep the current geometry). For my disparate riding (60% year-round commuter, 25% road, 10% single-track. 5% dirt-tourer) even an all-rounder is going to need different wheels (an implicit vote for 'rdSogn').

Final thought is that G. Ted's opine that "a point in every direction is the same as no point at all" (paraphrased) highlights the inherent dichotomy in the all-rounder concept: my toolbox is full with single purpose tools, but I bring a single multi-tool on the road. Each has their role. In this case, specialize in generality.


Guitar Ted said...

@Jim G: My point as to geometry maybe should wait until we get to that discussion, but briefly.... I see a lot of "cross geometry" 700c bikes. Bikes that handle the type of tires and terrain I want to ride, but don't have "all day comfort", and some of that is due to the cross specific nature of the design. I'll chime in more specifically later...

@Pax: Specialize in generality? Sorry, I ain't buying in if this is where Rawland ends up. I have a very specific idea for what I would like to see, and versatility in the way some of the posters here are defining it isn't it.

I would suggest that there are plenty of those products already out there, and what I have in mind, no one is really doing yet. Not as far as I can tell. Oh, and a 29"er isn't what I have in mind at all, for those of you who know about me.

Doug said...

I see 700C as much more practical and versatile given the rim and tire choices available today. Versatile bikes with lots of clearance, NOT suspension- based designed.. are not that numerous.
Good luck and God speed!

Anonymous said...

will the L be as large as the original large? anyway, if so, I owned one of the original larges and the main thing that struck me was the chainstays seemed too long for the front-center of the bike. that, and the oversize tubing... so, I think 650b is fine, and I doubt I could improve on prior tubing comments.

(and when you ask for color comments, I will vote for the original red).


James Black said...

I think Alex has it right here. I imagine this bike as having the potential to be a lightweight TIG-welded 650b frameset that can fit both knobby offroad tires and Hetres with fenders, and throw in a handsome fork with a nice bend and a lot of offset, and it will be just right.

James Black

Stuart said...

Day late on this... I would be most interested in the rSogn if Alex's tubing recommendations were followed and if it's 650b (or at least 650b-optimized, meaning canti posts in position for 650b wheels).

I think the "switching to 700c tires in the summer" (not to pick on that commenter) is a red herring. You don't lose anything by using 38mm 650b tires in the summer. There are several nice, fat, fast, smooth 650b tires that fit the bill. They will NOT slow you down.

Availability of 650b rims and tires won't be a problem in the future (talking USA here), unless availability of everything becomes a problem.

Anonymous said...

650B and keep the generous tire clearances of the original Sogn.
Flexiest tubing you can find!


Rob in Seattle said...

@Guitar Ted -I take your point about the challenge of designing for two different wheel sizes. I'd choose 650B then, with clearances similar to the original Sogn. I'd love to be able to run Pari-Motos with fenders and Quasi-Motos without.

jimmythefly said...

I like the tire clearances of the original Sogn. I don't have a dog in the canti post fight, because I use discs and 700c wheels on mine.

superfreak said...

please no 650b. seriously, as soon as someone comes out with a plush 559 fat tire, 650b will immediately be obsolete. think about that for a moment and you'll agree. 584 is only 4% greater in diameter than 559. 650b offers nothing new except hype.
thx superfreak

rmb said...


giant hogweed said...

I would vote for a lightweight version of the original 650b sogn

Michael_S said...

since this is Sept 9th I 'll include brakes in my input. I'm squarely in the 650B camp and standard road bike tubing ( see Alex's note). And my preference would be for brazed on canti studs, there enough good brakes out on the market now to meet anyone's needs. And I really like the dedicated size approach, ditto on the Pari/moto with fenders/Quasi moto w/o clearances. Mike

Protorio said...

Late, but... 650B/58mm, with the option of running 700c cross/monstercross tires. Just like the original Sogn. I have canti posts and rung the Paul Motolite BMX brakes - just about perfect.

Those huge 650B tires are a blast, and you can run the fast 650B event tires too.

Keep it the same. There is nothing else like it.