Comparing Kona Sutra and the Surly LHT

[tpejoe]

I am considering buying a  Kona Sutra or a Surly Long Haul Trucker. I just saw a fruitful discussion comparing two other bikes.

Does anyone have anything to say on these two bikes?

Thank you,  Joe Earley

[waynemyer]

I had a 2008 Sutra.  The 2010 might have remedied some of the shortcomings, but I have not had opportunity to ride one yet.

But here are my takes on the Sutra:
http://waynemyer.com/2009/10/would-i-do-it-again.html
http://waynemyer.com/2009/10/whats-wrong-and-whats-right-with-kona.html
http://waynemyer.com/2009/10/more-sutra.html

I will add that while many poo-poo disc brakes, I really think they may be talking about something other than Avid BB7 or never ride in foul weather.  If you don't ride in foul weather, you probably don't need disc brakes.  Or, if you're going to be out for 10,000 miles without opportunity to buy new brake pads, then discs might be the right choice.

Also, the wheelbase on the Sutra is short.  If you have clodhoppers, like me, you may get heel strike.

[paddleboy17]

When I built up my Waterford, I had a choice between disk and cantilever brakes.  I saw this as a hard choice to make.  With disk brakes, I worried about shearing spokes under load with a fast stop.  With cantilevers brakes, I worried about glazing pads and overheating rims (and losing the tire) under load with a long slow stop.  Since Waterford will do whatever you want, I went with cantilever brakes all around, and a disk drag brake in the back.  It is a sweet, but expensive setup.

Anyone have a better feel on the actual physics of disk brakes?

I just saw with the superior stopping power of disk brakes, an opportunity to shear spokes.   All the stopping action is close to the center of the wheel, and all the load action (aka moment of inertia) is out at the rim.

[waynemyer]

I have never broken a spoke with disc brakes, including hauling trailers with loads up to 200# (I weigh 190#) on stock wheels.  I think we would be seeing a lot more catastrophic failures spoke loads were much higher than normal.  Under rim braking, there is still a moment being applied to the spokes via the hub due to the inertia of the bicycle.  I have yet to see an explicit finite element analysis of the various forces in rim braking vs. disc braking, so this is my best guess based on my engineering experience.  But if spoke failure was a real issue, either it has already been engineered out or there would be more buzz regarding the matter. 

I also think that disc-specific wheels are currently overbuilt, in anticipation of the forces applied through the hub.  I have yet to see a disc wheel built with butted spokes (including my current custom set), yet if the moment arm of the hub was actually at risk of deforming the spokes, a butted spoke would be much better than straight gauge (ref: Art of the Wheel).

Properly configured, most bicycle braking systems have approximately equal braking power.  It is a matter of matching the mechanical advantage of the lever to the brake caliper (ref: Bicycle Science, and Sheldon Brown).  Discs have the advantage of all-weather capability and superlative modulation. 

Aside from one's specific braking requirements, I feel that choice of braking system is a religious argument.  Many peoples' minds are made up and they refuse to be confused by the facts.

[Tourista829]

Although, it is not considered anymore, I have an Arai drum brake on my tandem, that I use as a drag brake, in conjunction with my cantilever brakes. The cantilevers are easier to maintain and give good stopping power under a full load. The drum brake is relatively inexpensive, easy to maintain, and although heavier than a disc brake setup, is also great for long controlled descents. The old setup was to have both cantilevers on one brake and the drum on the other. I put the cantilever brakes, back to a conventional setup and took an old thumb shifter and connected it to the drum brake. I simply dial in the amount of resistance and it holds it though out the descent and forget about it. Like Paddleboy17, I see merit in a dual braking system and not having to worry about rims heating up, blowouts, sheered spokes, and glazed brake pads. The physics would be interesting between disc and cantilever brakes. I will consult someone on it.

As to the two bikes, I see a lot more Surly LHT's on the road than the Kona Sutra. However, the Sutra appears to have disc brakes, fenders and front/rear racks standard. The front crank is a little to high a gearing for me and if you are getting a frame 54c or smaller look out for toe overlap on a bike with 700c tire.  

[denver_whitest185]

there is a significant reduction in shearing forces when using rim brakes instead of disk brakes. that's why Buell (RIP) created rim mount brakes for their motorcycles, enabling them to cut a significant amount of weight off their wheels.

However, that is for a significantly heavier motorcycle that has to deal with MUCH higher speeds. i really doubt you'll see any yielding of quality spokes from the shearing effect due to having disk brakes instead of rim brakes.

I think for the money, you get a more complete package with the kona.

[whittierider]

Or, if you're going to be out for 10,000 miles without opportunity to buy new brake pads, then discs might be the right choice.

Shouldn't that say, "then discs might not be the right choice"?  My reading on disc brakes suggests the pads don't last anywhere near as long as rim-brake pads.  Many on the tandem forum said their disc-brake pads only lasted a thousand miles.  Even on our tandem with a gross weight of 350 pounds, the mini-V rim brakes are able to lock up even the front tire, wet or dry, with a single finger on the lever, and the pads look like they will last 20,000 miles.

I just saw with the superior stopping power of disk brakes, an opportunity to shear spokes.   All the stopping action is close to the center of the wheel, and all the load action (aka moment of inertia) is out at the rim

and they stress the frame and fork differently too (closer to the dropouts), requiring a beefier, heavier bike.  The disc brakes themselves are heavier too.  But again, as to stopping power, see my note about our tandem's rim brakes above.

Under rim braking, there is still a moment being applied to the spokes via the hub due to the inertia of the bicycle.

It's very minimal by comparison though, and there's no torque at the hub itself.

It is a matter of matching the mechanical advantage of the lever to the brake caliper

+1, and having the right compound.  Consider it standard practice to use Kool Stop pads to replace whatever pads the brakes come with.  You'll get better braking and longer rim life.

+1 on the drum brake for descents on the tandem, but it's overkill for most single bikes.  Deep-V aluminum black-anodized rims will get rid of the braking heat the best, and the deep V makes for a very strong wheel.  The deep V makes for more surface area to get rid of the heat, the aluminum conducts heat three times as well as steel, and the black anodizing increases the emissivity, making it able to radiate more heat without exceeding a given temperature.

The main benefit I see to disc brakes is if you ride in rain a lot, since sand, stuck to the rims by the wetness, is like sandpaper if you have rim brakes, grinding down the rims and shortening their life.  It's not a problem though for riders who only occasionally ride in the wet.

[paddleboy17]

Hey Tourista829, thanks for your kind words on dual brakes. 

I don't use the drag brake very often, but I am grateful that I have it.  I would like to have had it when I rode Cape Breton Island, and I was grateful to have it descending from the GAP into Meyerdale, PA.  My touring partner on the GAP had marginal rear rim, and split his rim due to the clamping forces that he subjected the rim to while descending into Meyerdale.

[Tourista829]

Paddleboy17, you are welcome. I have a physics professor checking on the physics of the two braking systems. Although we have a road/touring Santana Tandem which weighs in at 35 lbs, with two of us on it and full gear, it builds up speed quickly on descents. (there was a day when 50+mph descent were fun, but...) If I want 20% drag or 40% drag I just set it, forget it, and if I need some additional braking use the cantilever brakes. When I was looking to purchase the Comotion, the Americano had the option to put a drag brake on it because of the spacing on the tandem rear end. Although heavy, I may look into putting an Arai drum brake on it. I will write you on your email and catch up. Bob

[velo]

As for pad life on discs I just swapped out at front pads on my Sutra after 4500 miles of touring a loaded commuting. This is far more life then I get out of rim brake pads. As for shearing spokes with discs I've never seen this in a few years of working in shops and lots of years fixing bikes. I've heard of hub shells that sheered when they were first making discs, but that hasn't been an issue in a long time. My general feeling on discs are positive, but you do have to know how to set them up and maintain them.

As for the Sutra specifically, I have one of the older ones with sliding drop outs that I picked up NOS last year. It is a great bike, it is a tank, but it is a great bike. The handling is stable and neutral, it handles well under load. I road with front and rear bags and a little weight on the front end made the feeling very stable if a little slow. 

My build is a 3 x 9 shimano mix with XTR/XT/Ultegra/Tiagra/Dura Ace and other parts. The wheels are XT hubs with Mavic disc specific rims. In front I'm running a Schmidt SON 28 paired with an Edelux. For brakes I have Avid BB7 Road mechanic discs.

I haven't ridden a LHT for any real length of time, but friends who have it like it. Both are good bikes and real stout. The LHT comes with 26in wheels in smaller sizes so you might consider that. If you can I'd try ridding both and see which bike you like better. Nothing like riding them to have a better idea of which one is for you.

[waynemyer]

Shouldn't that say, "then discs might not be the right choice"?  My reading on disc brakes suggests the pads don't last anywhere near as long as rim-brake pads.  Many on the tandem forum said their disc-brake pads only lasted a thousand miles.  Even on our tandem with a gross weight of 350 pounds, the mini-V rim brakes are able to lock up even the front tire, wet or dry, with a single finger on the lever, and the pads look like they will last 20,000 miles.

You and I have explicitly already had this discussion.  Pad selection is a close second in importance to matching the mechanical advantage of the lever to the caliper system.  On a tandem, I would be surprised to see 500 miles on a set of organic disc pads.  I was getting less than 1000 in foul weather.  Sintered metallic or ceramic, on the other hand, I finally replaced a set of disc pads simply because pads were on sale.  I have now lost track of the mileage, but it was well over 15,000 miles.

The basic truth here is: every braking system has its advantages and disadvantages. Most systems, in my experience, are roughly equal. The individual needs of the rider should determine the choice of system.