Time for some philosophy... concerning bike manufacturing.

MikeD · Sep 15, 2004

You can't compare MX and bicycles. The requirements are so much different, as are the economies of scale involved in production. Plus, there's simply more overall experience designing motorcycles than full-suspension bicycles. I'd wager that a lot *more* engineering goes into a well-designed DH bike than most MX bikes...reason MX bikes might seem to last better is 1) they're stronger, and can afford, relatively, extra weight in order to be stronger and 2) they are crashed less...there's more of a sense of consequence on a motorcycle, and when a crash is bad enough to screw up a frame, the rider's condition probably takes precedence over whining about the bike. Plus, MX riders don't expect a frame to be warrantied (much like your point), because they *crashed* it! Bicycle riders, though, can't afford the weight penalty for a frame strong enough for repeated big crashes, yet they perversely CAN often afford to ride outside their envelope and crash a lot more than an MX rider; a Dh bike crash seems relatively normal for many of us, and we walk away from most without any injury worth noting.

James | Go-Ride · Sep 15, 2004

Well in all fairness, MX bikes weigh 220 lbs+, for example ONE of the WP fork legs on Scott's EXC200 weighs 12 pounds. If we all rode 80 pounds DH bikes made of steel with 50 pound frames they probably wouldn't break.

This is a good example of why Honda is using DH to improve their MX stuff . . .

Damn True · Sep 15, 2004

You keep mentioning MX level design and engineering. MX bikes suspension is not all that sophisticated, and the frame designs are all borrowed from road racing.

Heck the Honda DH bike, for all it's hype is still a single pivot. Yippee, just like my old Santa Cruz Super-8.

Roasted · Sep 15, 2004

math2014 said:
Hi all,

I just wanted to share some thoughts and open some discussion. Before starting, i would like to say that i havent ridden that many modern bikes, i havent broken any (yet) but i have heard many cr@p stories here and on other forums. FR/DH frames seem to be considered dispensable, or at least this is how i understand it from what i read. At the same time, these frames are quite expensive. So whats the catch you might ask.

I think it has leveled out a bit. You don't hear of the catastrophic failures of a few years ago. As long as people stick with a bike built for your 'arena' I think things are signifigantly better than say 2 or 3 years ago...(a djer fork really can be used for djing now...for example)

What i would like? I would like either dispensible frames (that last 2-4yrs) on a small price. OR, MX level frames at high price, where people have really done their job designing , analysing and engineering the frame like on an MX bike. From what i heard from MX friends, MX bikes do break but at a much smaller ratio in comparison to DH/FR frames yet they endure severe impacts etc.

You can get mx level frames for extraordinary prices. You can also get disposable frames. There is just a bunch of boutique companies in the middle that people tend to love that barely offer either. Ironhorse is my next bike, either that or another bighit comp. Both VERY reasonable, good reputation and strong with acceptable warranties. Then you also have bmw and nicolai...boutique bikes but holy crap are they strong but at boutique prices. There are definately those options out there, you just have to avoid the hype of the industry. (aka the magazines)

So point 1. Better frames, that LAST, and they dont trouble people with the slightest notion of cracks or anything similar.

Again..it isn't THAT common, and really the mx riders I know have similar concerns and do similar checks to myself. If you are constantly worried about your frame breaking, I wouldn't suggest dh or fr as a primary sport.

Point 2. SMALL warranties, i would really like only 1 yr warranty which would cover ONLY manufacturing defects, against ANY use as long as it complies with the character of the bike. (XC bike XC use, DH bike...DH use even racing).

Who doesn't offer at least a year? (keep in mind I never look at boutique bikes as I would never buy them, being on a unique bike means absolutely nothing to me personally haha)

If you crash it? NO warranty. At the same time, a clearly stated crash replacement program like the one that Transition does. I will pay for my error, yet i want to know what i ll have to pay if something goes wrong.

Newer smaller companies trying to make a name for themselves seem to be doing just this. Some great options at cheap prices if something breaks.

Point 3. Where the hell is steel? Ok i understand that MX bikes got more bhp power hence weight is not that significant in comparison to a mountain bike, BUT, my recent research on road bikes, showed me that people there do Big research concerning steel usage, and they have reached allu in stiffness and weight (well almost), Colombus Ultrafoco, etc...

I wonder if someone could do the same and introduce good FR/DH steel tubing, other than traditional 4130. So far, BMW and Keewee are pristine examples of Steel bikes, yet they use simplified tubing.

Thing is that with steel usage, the frame will endure more dents rocks etc, crashes and various other habbits we tend to have while riding DH.

No idea. I don't know enough about manufacturing materials to make a justified answer...To guess...maybe steel has such little appeal these new production methods wouldn't justify the costs...maybe its weight...

dw · Sep 15, 2004

A lot of spot on and very good points by the responders. Its so good to see how this topic has evolved over the last few years. I remeber a page long bolwout in MTBR a few years ago where nobody could understand the economy of MX and bikes and how they differ.

First off, in MX, there is a weight limit. This is good, becuase if there wasn't, MX race bikes would all weigh 120 lbs and cost $40,000 each. When was the last time you saw a downhill fork with a CAST (not forged) set of triple clamps. I cant even think of on, but its commonplace in MX.

MX bikes have power to work with and a weight limit, they also have frame structures that have much higher area moments of inertia than bikes. Simply put, the tubes are farther apart. This lets designers build steel frames that can hold up, are reasonablky light and stiff enough to work. Most of these frames are built from 1020 and the like. Not a ton of 4130, and certainly not much in the way of air hardening alloys like found in bikes. No butted tubing, nothing. Why shoudl they? The cost would go way up, and the ride wouldnt change that much, as they have to make the weight limits anyways.

dw

James | Go-Ride · Sep 15, 2004

Clarification for those not in the know: DW is referring to the AMA's MINIMUM weight limit for moto bikes.

Remember the e-fuss regarding the 24 wheel ban a few years back from the UCI? Can you imagine the explosion if the UCI or NORBA had a minimum weight limit?

MikeD · Sep 15, 2004

Also, think of it this way: the MX bike that, say, Pastrana is riding costs a LOT more than your average CR250 or whatever. I've heard figures ranging from $30-100k, but it's a lot, many many times more than the cost of the stock Honda.

But, when you spend $5k on a new cutting-edge Foes or Intense M3 or Iron Horse or Specialized or whatever, you're riding nearly the EXACT SAME BIKE as the top pros...technology that's the offroad bicycle equivalent of formula 1 cars.

MD

binary visions · Sep 15, 2004

MikeD said:
But, when you spend $5k on a new cutting-edge Foes or Intense M3 or Iron Horse or Specialized or whatever, you're riding nearly the EXACT SAME BIKE as the top pros...technology that's the offroad bicycle equivalent of formula 1 cars.

This is a good point, and interesting in that there are not many non-pedestrian sports where the average Joe even has access to the equipment that the pros ride.

Most recently, though, there has been a slight shift in that truth. Honda in particular, but also B1 - and maybe Nicolai though I haven't see pictures of the pros riding g-boxx equipped bikes - have brought a new element into the sport. They are giving technology to the pros that is simply not available to the consumer, and is ludicrously expensive to boot (at the moment anyway).

Not just the gearbox, but the Showa custom tuned suspension on the Honda. Sure, pros often get gear that's not publicly available, but it's usually just a matter of waiting a year before that gear is ready for public release. I wonder if this is a sign of more of this to come - that is, proprietary technology given to the top pros that may never become available to the public (or, rather, not available in the same form it's raced in, and not in a reasonable amount of time). That's the way it is in most motor sports...

Kornphlake · Sep 15, 2004

simply put many companies are designing products rather than engineering products, the differance is that one looks burly and the other performs independant of it's appearance. I'd be suprised if even some of the steel bikes have actually been engineered rather they went through a process of build, test, redesign, build, test, redesign... Not that the throw something together and see if it works method is wrong, it just won't produce the level of quality that an academic engineering process will.

dw · Sep 15, 2004

Somehow I deleted a paragraph there so here is some more. MX bike frames are MIG welded, not TIG. cuts cost, preformance decrease minimal, especially for 1020.

For bicycles, your top level race bikes (the ones with the highest structural efficiencies that can still withstand a crash) are going to have carbon or aluminum front ends. Forget about ti and steel. Both have too high of a density and stiffness to allow thin enough sections to build front triangles that have the blend of stiffness, dent resistance, and strength (all at the same time) that aluminum and carbon offer. You can still build a great trail bike, and even a nice race bike, but if you are looking for the most out of your suspension, for a BICYCLE, aluminum and carbon are very tought to beat.

Now, to hop on a semi related tangent:

One of the most infuriating things to me about the bike industy is to read manufacturers over and over tell how steel and ti bikes have infinite fatigue lives. That is just an asinine comment that seems to be regurgitated all over the place.

Here is the truth:

Steel and ti as materials have fatigue LIMITS. This means that IF AND ONLY IF a designer uses enough of said material, then and ONLY THEN it can have an infinite fatigue life. Take for example an agressive use hardtail, say like the Evil Soverign, which is a steel frame design using custom triple butted Reynolds 853 and 725. A damn strong steel bike with a very high structural efficiency. This bike weighs in around 5.7 lbs. In order to have an infinite fatigue life, this bike (by my calculations) woul6 have to weigh in at LEAST 9 lbs. Thats with Reynolds tubing! With 4130, we're talking double digits easy. Who the hell would want a bike like that? I wouldn't. I'll take the 5 lb version that I know will ast me 5 years minimum and take everything I can dish out. By then I am going to want a new Sovereign anyways.

dw

buildyourown · Sep 15, 2004

I've long thought that steel is the ideal material for DH bikes. It's fatigue qualities make it ideal for abuse and it is repairable by many people. The main reason you don't see it used more is because of marketing, and the design challenges it presents. It is harder to design a FS steel bike than it is to build an aluminum one. There is a bigger penalty for excess material left behind.

Also, tube manufactures don't offer butted tube sets in sizes suiteable for DH bikes. Many designs with pivots in the center of tubes, would require custom butted tubes. This is very expensive. Hence why nearly all steel dh and freeride HTs are built with regular boring 4130. It's cheap and available in every size imaginable.

Just for reference, by switching from straight gauge 4130 to butted HT cro-mo, I saved a pound off the front triangle. Using stock tubes, it cost less than $100 in material.

Kornphlake · Sep 15, 2004

dw said:
Here is the truth:

Steel and ti as materials have fatigue LIMITS. This means that IF AND ONLY IF a designer uses enough of said material, then and ONLY THEN it can have an infinite fatigue life. Take for example an agressive use hardtail, say like the Evil Soverign, which is a steel frame design using custom triple butted Reynolds 853 and 725. A damn strong steel bike with a very high structural efficiency. This bike weighs in around 5.7 lbs. In order to have an infinite fatigue life, this bike (by my calculations) woul6 have to weigh in at LEAST 9 lbs. Thats with Reynolds tubing! With 4130, we're talking double digits easy. Who the hell would want a bike like that? I wouldn't. I'll take the 5 lb version that I know will ast me 5 years minimum and take everything I can dish out. By then I am going to want a new Sovereign anyways.

dw

Thanks for reinforcing my point, somebody who does a notebook full of calculations versus somebody who rides a proto and assumes it will last forever. I know who I'd rather give my money to.

dw · Sep 15, 2004

Kornphlake said:
simply put many companies are designing products rather than engineering products, the differance is that one looks burly and the other performs independant of it's appearance. I'd be suprised if even some of the steel bikes have actually been engineered rather they went through a process of build, test, redesign, build, test, redesign... Not that the throw something together and see if it works method is wrong, it just won't produce the level of quality that an academic engineering process will.

I truly believe what you say. The build test, rebuild repeat method is good and can build a really good bike. been proven many times.

I really feel though that the engineer, analyze, build, test, analyze, re-engineer, re-analyze, rebuild repeat method, although more time consuming and obviously requiring special skills and equipment is the way to go if you want to build a truly great bike (or widget). Not that its a guarantee to building something great. Thats been proven to be false plenty of times too, but I think it helps your chances.

I'd rather spend time working on engineering reasons why a product is superior versus working on thinking up marketing terms on why a product is superior. Those come later.

dw

oly · Sep 15, 2004

dw said:
Now, to hop on a semi related tangent:

One of the most infuriating things to me about the bike industy is to read manufacturers over and over tell how steel and ti bikes have infinite fatigue lives. That is just an asinine comment that seems to be regurgitated all over the place.

Here is the truth:

Steel and ti as materials have fatigue LIMITS. This means that IF AND ONLY IF a designer uses enough of said material, then and ONLY THEN it can have an infinite fatigue life. Take for example an agressive use hardtail, say like the Evil Soverign, which is a steel frame design using custom triple butted Reynolds 853 and 725. A damn strong steel bike with a very high structural efficiency. This bike weighs in around 5.7 lbs. In order to have an infinite fatigue life, this bike (by my calculations) woul6 have to weigh in at LEAST 9 lbs. Thats with Reynolds tubing! With 4130, we're talking double digits easy. Who the hell would want a bike like that? I wouldn't. I'll take the 5 lb version that I know will ast me 5 years minimum and take everything I can dish out. By then I am going to want a new Sovereign anyways.

dw

SPAM!!!! HAHA, J/K..... Of all the bike industry engineering insiders you seem to have a real educated background that can always provide great info, yet still say it in a way us community college folks can understand......

butocabra · Sep 15, 2004

UCI does have a minimum weight limit for road bikes (and I assume for mtn as well). I think cannondale had a road frame they had to strap weights to to make the minimum weight (somewhere around 15lbs, IIRC). the riders had jerseys saying something like "legalize my bike". Pretty funny stuff.

RhinofromWA · Sep 15, 2004

MikeD said:
Also, think of it this way: the MX bike that, say, Pastrana is riding costs a LOT more than your average CR250 or whatever. I've heard figures ranging from $30-100k, but it's a lot, many many times more than the cost of the stock Honda.

But, when you spend $5k on a new cutting-edge Foes or Intense M3 or Iron Horse or Specialized or whatever, you're riding nearly the EXACT SAME BIKE as the top pros...technology that's the offroad bicycle equivalent of formula 1 cars.

MD

Not really dissagreeing with anything in these posts with the acception of one slight modification.

Pro MX/Offroad bikes are not unlike what you buy off the showroom floor. It is the attention to detail and fine tuning that yeilds the most benefit. Many pros on teh national level are running "stockish" bikes with performance upgrades....they all get some sort of suspension tuning and engine work even if it is jsut an after market pipe. While I am sure Pastrana's MX bike is spendy the most expensive work is done taking the bike from 99% right to 100% right. There is much less unobtanium (word from the dirt bike mags for stuff John Doe can't get) out there now a days. That is what makes the works bikes sought after....the minute attention to detail. A privateer with a stock bike and some suspension work and aftermarket pipe silencer can win if they are up to it. The bike is not at that big of a disadvantage.

A pro DHr's bike is worth more than the sum of it's parts....it is the time spent to make it "right" that can be part of that cost.

MX bikes wear out in a season for top level racers...maybe less. A MX bike will last the weekend warrior a year or 3(or more) but their performance needs are less. I beat the piss out of my bikes growing up and they were worked after the 2-3 year mark.

Does it fail when it is worked over? Not really, it is just tired and not something a simple engine rebuild would cure. It is just worn out.

Would a minimum weight for DH racing be bad? Just raising the question. It helped some in MX and if you ask others it hurt it. Taking that "works" bike out of MX lost part of it's appeal, but made the playing field closer for everyone....in turn allowing stock bikes to grow and improve so everyone benefited and the performance of yesterdays works bike is delivered at the price of a todays stock bike. It evened the field....or brought the gap close.

TWISTED · Sep 15, 2004

Concerning steel and MX bikes, I would like to add the fact that Honda motocross bike frames have been aluminum since 1997 and the new Yamaha YZ motocrossers have aluminum frames this year.

The strongest attribute of the motocross dirt bikes is their refinement. Visibly there has been little change to them in the last 10 years. Todays MX bikes are nearly to the point where they are interchangeable brand to brand. By reviewing specifications of bikes of the same size but different brands, you will see the same dimentions, geometry, and configurations throughout. Refinement. They have figured out what works and have built upon that concept.

It is possible that in the future all downhill bikes will be the same after going through a similiar process as motocross bikes.

zedro · Sep 15, 2004

TWISTED said:
It is possible that in the future all downhill bikes will be the same after going through a similiar process as motocross bikes.

exept that alot of bike designers enjoy the 'artistic freedom' of designing them, where the lack of pure practicality and the designers allegiance to specific concepts and patents will probably keep the field pretty diverse.

But if there has been any convergence in design, it would be in the foward single pivot type designs IMO.

TWISTED · Sep 15, 2004

zedro said:
exept that alot of bike designers enjoy the 'artistic freedom' of designing them, where the lack of pure practicality and the designers allegiance to specific concepts and patents will probably keep the field pretty diverse.

But if there has been any convergence in design, it would be in the foward single pivot type designs IMO.

Agreed, but I would not be surprised If in ten or fifteen years from now all the competitive and popular downhill bikes share the same design format, (dw-link, of course! and Dave's a multimillionair

) just as dirt bikes in the late sixties evolved from the mixed bag of odd and interesting ideas.

I think there are many designs out now that work very well for certain specific applications but may be passed over in time due pressure to conform or maybe an "overall" performance advantage of a particuliar design.

zedro · Sep 15, 2004

TWISTED said:
Agreed, but I would not be surprised If in ten or fifteen years from now all the competitive and popular downhill bikes share the same design format, (dw-link, of course! and Dave's a multimillionair ) just as dirt bikes in the late sixties evolved from the mixed bag of odd and interesting ideas.

I think there are many designs out now that work very well for certain specific applications but may be passed over in time due pressure to conform or maybe an "overall" performance advantage of a particuliar design.

come to think about it, internally mounted frame transmissions could be the key to convergence, and i could imagine VP type 4 bars going on the way side, reserved for 'traditional' derailler bikes.

TWISTED · Sep 15, 2004

zedro said:
come to think about it, internally mounted frame transmissions could be the key to convergence, and i could imagine VP type 4 bars going on the way side, reserved for 'traditional' derailler bikes.

Ahhh, you got it. I agree (sorry Dave).

Brazil_boy · Sep 15, 2004

got milk?

dw · Sep 15, 2004

We will see, we will see...

There is a lot more knowledge and technology being shared today than ever before. Advances are being made everywhere, in motocross and in bicycles.

I'll also go out on a limb and predict that the forward single pivot for conventional derailleur bikes will be gone except for very low end consumer bikes in 10 years...

Dave

dw · Sep 15, 2004

(so what I am saying is that if/when I build a new gearbox DH bike, it sure as heck will use a dw-link suspension)

TWISTED · Sep 15, 2004

dw said:
We will see, we will see...

I predict that the forward single pivot for conventional derailleur bikes will be gone in 10 years...

Dave

What will they be selling at Wal Mart?
Oh yeah, in ten years those customers will all be tearing up the sidewalks on their ion powered scooters with patented dw-link suspension.

dw · Sep 15, 2004

haahhaah

you beat me before i edited

I bet walmart will have the forward single pivots, and also crap-tastic linkage bikes with poor toleranes.

RE the scooters:

if they do, you and I will sit on your yacht and we will drink martinis!

TWISTED · Sep 15, 2004

dw said:
(so what I am saying is that if/when I build a new gearbox DH bike, it sure as heck will use a dw-link suspension)

Would the dw-link be necessary?
I thought that if you used a high pivot and isolated the drive forces from the suspension, a design such as yours' wouldn't be needed.

TWISTED · Sep 15, 2004

Dave, we've got a real neat black bike frame sitting on a table at work. ? PM me

dw · Sep 15, 2004

TWISTED said:
Would the dw-link be necessary?

Heck yeah, it would definitley have all of the same performance advantages as on a derailleur bike.

I thought that if you used a high pivot and isolated the drive forces from the suspension, a design such as yours' wouldn't be needed.

Problem with that is that you can't "isolate the drive forces from the suspension" with a high single pivot like on a Motocross bike. Its just that a motocross bike doesnt complain about pedal feedback and the like.

shock · Sep 15, 2004

just thought I'd throw my two cents in...

Nobody mentioned that an mx bike has a huge structural advantadge in that the engine is a stressed member of the frame. Big lump of metal helping to hold things together.

Also, I disagree that DH bikes are crashed more than mx bikes, at least from my own personal battered body's experience, I have crashed far more, and at much higher speeds, and sustained far more damage to bike and body on an mx and/or desert bike than on a dh bike, although I was faster then.......

Think of the force of a 200+ pound mx bike cartwheeling through the desert at 60 mph!!!

Also NOTHING NOTHING NOTHING has an "infinite fatigue life, not even an anvil....It might be "calculated" to have one, but those calculations are always subject to the assumtions necessarry to make the calculation in the first place i.e. force inputs, structural assumptions and number of cycles in "infinity".

If something is designed close enough to its limits of stress in use, IT WILL FAIL, sooner than later. IF it is designed with a HUGE factor of safety, it will fail later if it's used long enough. More than likely it will be replaced with something new before that happens. But it still has a very finite fatigue life.

zedro · Sep 15, 2004

dw said:
(so what I am saying is that if/when I build a new gearbox DH bike, it sure as heck will use a dw-link suspension)

but will your second or third one will? just think back a few years and then a few more at how ones design philosophies change over time, exchanging one benefit for another. Right now we're in the Renaissance period, we'll have to see when things get a little more hum-drum...

geez, i think me and Twisted's views are gradually morphing together as this thread moves along...

shock · Sep 15, 2004

Problem with that is that you can't "isolate the drive forces from the suspension" with a high single pivot like on a Motocross bike. Its just that a motocross bike doesnt complain about pedal feedback and the like.[/QUOTE]

Are you sure about that????????? Never say never.......

TWISTED · Sep 15, 2004

Wouldn't having the rear suspension pivot around the drive cog in a high pivot location, such as on the jack shafted Brooklyn race-link isolate the two forces?

zedro · Sep 15, 2004

also, theres a point where we are just splitting performance-hairs, where some 'impressive' engineering numbers between systems dont necessarily translate into a noticible or justifiable performance difference, where a more simplified and practical design that also lowers cost and maintenance concerns is deemed more disirable.

TWISTED · Sep 15, 2004

TWISTED said:
I think there are many designs out now that work very well for certain specific applications but may be passed over in time due pressure to conform or maybe an "overall" performance advantage of a particuliar design.

Agreed?
Damn Zedro, you sound smart.

TWISTED · Sep 15, 2004

Now I need to get off this forum so I can try to design a MC San Andreas tricycle for Interbike. :thumb:

Time for some philosophy... concerning bike manufacturing.

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