Who’s made the best road suspension fork to date and what made it good/better?

[Tobias]

Following the economy and politics lately has me a little down, so I thought turning my attention towards something more enjoyable was advisable. My first thought was to ask about the kind of bikes third-world cyclist ride, but I’d like to keep it a bit more optimistic. The thread on the Roubaix fork got me searching for data on the different types tried over the years – obviously none totally successful for different reasons – which made me wonder how they differ and what advantages some have over others.

I’ve basically found three types – don’t know what they are called by category so I’ll describe their general characteristics in lay terms.

The first type used a long time ago appears to be fabricated with many external linkages. A spring or springs somehow control movement between the parts as to suspend the front wheel. I’ve seen variations of this on older motorcycles and scooters as well.

The second type is like the MTB fork. Rock Shox made a few road units about a decade ago but discontinued them. Now there appears to be some models which are similar but much heavier-duty looking for 700C wheels. They seem to be marketed towards “metro”, “hybrid”, or even “cross” use and have a lot more travel than the original road designs. The originals had about 15 MM and new ones about 30 MM of travel.

The third general type seems to be the Cannondale head shock type. Appearance wise they look most like a standard bike and I’d guess they are relatively light since the fork itself can be carbon. I’ve seen pictures of older Moultons that had similar design and date back to the 60s, so it appears that placing travel in the head tube is not all that new after all.

There may be other types I’m missing entirely, but the major question here is what advantages and disadvantages do these have relative to the others. Appearance, weight, simplicity, durability, ride, handling, etc… If you can think of it (regarding road suspension forks), I’d like to hear it. And if you know of other types of forks, please let me know so I can look into them.

I know we’ve had a lot of specific fork threads, but I’m more interested in the history and progression. Where have we been, where are we going, and how close are we?

[alancw3]

the first one you mention. had one on an old schwinn. can't say that it functioned all that great though over nonsuspension fork. i think pee wee herman liked it!

[Blue Jays]

I suppose it would be an OK idea if it could be made sleek and somewhat lightweight.

[rockdude]

Check out Black Sheeps Faith Fork...

http://www.blacksheepbikes.com/

[palincss]

I don't think there's much contest here.

[Birddog]

Not a fork, but I remember these. Not too sure how well they worked.
http://www.bikepro.com/products/stems/stems_jpg/a2a_softride_ahead.jpg

Birddog

[Tobias]

I suppose it would be an OK idea if it could be made sleek and somewhat lightweight.That’s probably one of the most important questions of all – how much weight would it add and would it be accepted.

Although a road bike is not the same as a motorcycle, if forks can be made to work well on them at a price, then on a bike it should come down to weight more than poor performance. A high price could keep some out of the market, but if suspension forks actually worked well without adding too much weight I’d expect many would pay the price.

Don’t know how much these things add in weight. In the case of MTB type I’d expect it’s about 2 pounds – which is a lot on a road bike. That much would not be acceptable.

[Tobias]

I don't think there's much contest here.That's a cool design. Looks simple and relatively light. It's also very different than the other Moulton I saw a picture of. Depending on date it's an indication of progress, or design evolution. There has to be a reason he changed the fork design.

[Tobias]

Not a fork, but I remember these. Not too sure how well they worked.Thanks. The Softride is simple but only addresses the bars, not the bike. Same as the beam only addresses the saddle.

[RPS]

The Wikipedia page below covers many types of motorcycle forks used over the years and states:
“The main advantage of the telescopic fork is that it is relatively simple in design and therefore relatively easy and inexpensive to manufacture and assemble. It is also relatively light compared to older designs based on external components and linkage systems.”
http://en.wikipedia.org/wiki/Motorcycle_fork

To me incorporating telescoping suspension in the head tube seems very similar to a standard motorcycle or MTB fork but must provide a way to transmit steering input (i.e. – steering torque). On a standard telescopic fork, torque is transmitted by the two fork tubes being some distance apart.

If weight penaly is in the 1-1/2 to 2 pound range I'd expect many would skip it no matter how nice it rides. Only those touring or riding very rough roads may be interested.

I mentioned some time back that there was a Bianchi bike ridden in RAAM with an SUS21 fork. Those were made with very little travel and relied on short pivoting swing arms located down by the dropouts. I expect they work(ed) very similar to suspension front hubs; which are another type of suspension without involving the fork itself. I recently found that they were made or marketed by AeroSwing and most of the WEB pages were probably in Japanese – or other language I can’t read. Below are a couple of pictures. From the pictures I can’t tell how much movement they can actually get from the fork; and more importantly if there is a significant amount, how they control wheel roll movement.

Lastly, the picture in Wikipedia of the older Moulton bike shows telescope-type suspension in the head tube. I’d guess the newer design posted above by palincss is more costly but works better due to reduced friction.

[palincss]

That's a cool design. Looks simple and relatively light. It's also very different than the other Moulton I saw a picture of. Depending on date it's an indication of progress, or design evolution. There has to be a reason he changed the fork design.

The New Series was a redesign of the spaceframe Moulton. The new fork doesn't dive under braking, and is better damped as well. I said there wasn't much of a contest because the NS is undoubtedly the most sophisticated suspended road bike out there. I posted a pic of the 531 model - perhaps the stainless Pylon model would have been even more impressive.

[Elefantino]

It depends largely on what you're going to be using the fork for.

If you regularly ride rough, flat roads, then I don't see that there's been anything in the way of advancement since the Rock Shox Ruby.

http://www.chainreactioncycles.com/Images/Models/Full/4177.jpg

They can still be had, albeit used.

I wonder what a Ruby fork and a DKS suspension would ride like!

[Tobias]

I posted a pic of the 531 model - perhaps the stainless Pylon model would have been even more impressive.The Moulton site suggests they still make both styles of fork suspension. Is the company still in business?

[Tobias]

If you regularly ride rough, flat roads, then I don't see that there's been anything in the way of advancement since the Rock Shox Ruby.Is your comment about flat roads based on the added weight of the fork, or performance issues (other than weight)?

BTW, do you know what a Ruby weighed? I can't find data on them but would guess close to 3 pounds. Does that sound about right?

[RPS]

The new fork doesn't dive under braking, and is better damped as well.Anti-dive suspension geometry can serve as a reminder that good engineering often involves a lot of compromise since improving one area often adversely affects others.

Anti-dive suspensions built into the geometry (unlike a few active automotive types which are a totally different animal) can reduce or eliminate dive under braking, but it creates other disadvantages which may be more important to the rider. Based on fundamentals I expect the Moulton reduces dive but doesn’t eliminate it. I say this only because unlike a car, a bicycle has a very high center of gravity relative to the wheelbase length, and if total anti-dive was built into the suspension’s geometry, it would compromise the front suspension’s ability to deal with larger objects; particularly in light of the Moulton’s small wheels.

On the other hand, telescopic suspension like MTB and the Ruby road version promotes dive. That is, the braking force applied to the front wheel tries to compress the fork (albeit a small amount), which makes it dive down even more than the weight transfer would do on its own by working against the springs. But that “dive” disadvantage also makes it easier for the front wheel to get over larger objects – which in the case of an MTB may be a desirable trait.

Please understand I’m not criticizing the Moulton design in any way. I’m just noting that nothing is perfect for every occasion, and it’s highly unlikely that “marketing” types will say “our innovative suspension has anti-dive built-in………and by the way, because of that it doesn’t do XYZ very well”. ;)

[palincss]

The Moulton site suggests they still make both styles of fork suspension. Is the company still in business?

Absolutely the company's still in business. The Alex Moulton company merged operations with the part of Pashley that made the Pashley Moulton and the TSR, forming The Moulton Bicycle Company. Dr Moulton is President of the new company and Shaun Moulton is the General Manager with responsibility for worldwide sales and marketing.

There are several current production ranges, each with several models: the New Series; the AM, the original space-frame model that came on the market in the early 80s, with 17" wheels; the TSR, which is the latest generation of a less expensive version of the space-frame Moulton with 20" wheels; and the Bridgestone Moulton. This last is very interesting: the Japanese are big fans of the original F-frame Moulton, and a few years ago they commissioned Alex Moulton to design an updated version of the F-frame for Japanese production by Bridgestone. Originally available only in Japan, the BSM range is now also available in the UK, with some part of the assembly being done by Moulton in the UK.

So to bring this back to the original thread, that's three different fork designs and I'm not sure exactly how many different rear suspension designs. At one time the Pashley Moulton had the original AM rear suspension, while the AM's got a modified rear suspension based on the New Series design.

For those unfamiliar with Moulton bicycles, Alex Moulton designed the suspension for the original Mini. He got interested in bicycles during the 1956 Suez Crisis and, being an engineer, set about to try to improve the design of the bicycle to overcome what he saw as several shortcomings of traditional diamond frame design.

[Tobias]

So to bring this back to the original thread, that's three different fork designs and I'm not sure exactly how many different rear suspension designs.I’m not sure I’m following the third type of fork you mention unless it’s the one shown in the TSR WEB page. There were the two pictured in posts prior to this (one telescope in head tube and other with the exterior linkages) but I don’t see a third type in the Moulton page. Can you post a picture of which one you mean? BTW, do you currently ride a Moulton? If so, which model?

[Tobias]

For those unfamiliar with Moulton bicycles, Alex Moulton designed the suspension for the original Mini.Micro cars and other small vehicles of the time used small wheels (10-inch size wheels were not uncommon) to improve space utilization and reduce weight, knowing that it degraded ride quality. For that reason the suspension of the Mini needed to be better than most since they were less forgiving. That’s not to say that small wheels make sense in general for most applications. If we look at most modern cars (even the very small ones) they have much larger wheels and tires because they have inherent ride advantages.

It’s interesting that Moulton uses smaller wheels because they have less rotating mass, less unsprung mass, and less aerodynamic drag. However, some of those advantages are offset by having to add weight and complexity in the form of suspension. Not having ridden one, I don’t know if the suspension merely takes them to the level of a standard-size-wheel bike or if it surpasses it. If the latter, it would be interesting to see what they could do with a 700C bike.

[palincss]

I’m not sure I’m following the third type of fork you mention unless it’s the one shown in the TSR WEB page. There were the two pictured in posts prior to this (one telescope in head tube and other with the exterior linkages) but I don’t see a third type in the Moulton page. Can you post a picture of which one you mean? BTW, do you currently ride a Moulton? If so, which model?

The TSR is a variant on the original AM spaceframe design, and uses the same basic suspension design as the AM. The spring is in the head tube, and damping is via friction on the leading links.

I have an old AM.

[RPS]

It depends largely on what you're going to be using the fork for.

If you regularly ride rough, flat roads, then I don't see that there's been anything in the way of advancement since the Rock Shox Ruby.

http://www.chainreactioncycles.com/Images/Models/Full/4177.jpg

They can still be had, albeit used.

I wonder what a Ruby fork and a DKS suspension would ride like!Great suggestion Elefantino; and thanks for the reminder that there are still cool things out there others don’t want or need. I found and bought one – just got it yesterday and it seems in great shape. And the steerer is even the right length.

I normally don’t buy used bike parts, but after looking for a modern suspension fork to complement the rear and not finding one I like, I thought I’d give the Ruby a try. It’s not even close to what I’m looking for either but should be interesting and fun to play with anyway. I would have preferred to try it on my ti bike but being a 1” steerer I’ll install it on my steel Schneider instead.

I just wish I didn’t have so many preconceptions about what to expect which will undoubtedly bias my experiences and observations. Regardless I’m looking forward to riding it as soon as I get a new threadless headset.

[RPS]

BTW, do you know what a Ruby weighed? I can't find data on them but would guess close to 3 pounds. Does that sound about right?Approximate weight is just north of 2-1/2 pounds, so it will add about 1 pound over my Schneider’s stainless fork and stem adapter, and 2 pounds over my Calfee’s SL.

It is easy to see that compared to lightweight carbon forks the market for these Rubys would be next to zero. A two pound penalty in road cycling seems insurmountable. I don’t know what weight penalty a significant number of riders would accept for a suspension fork so as to create a sizeable market (i.e. -- to support mass production), but 2 pounds is excessive IMHO.

[93legendti]

To quote my daughter: "check this out!"

http://www.pantourhub.com/products.html

[RPS]

I first saw them a while back on the TitanFlex web page; and found them interesting.

A weight penalty for the front hub in the range of about 100 grams could make it more viable to more riders than full suspension forks, which seem to add considerable weight. Typical weight penalties for many fork types I’ve found were in the 500 to 900 gram range. Being able to use these front hubs with standard forks and frames should also make it more appealing and therefore viable to more riders.

I’ve been meaning to try one for a while but thought they would have limited acceptance for high performance bikes. One concern I had was that as the front wheel moves up and down the caliper brake pads may no longer line up with the rim’s braking surface. Also worth testing is its ability to control front wheel motion in the “roll” and “yaw” directions (i.e. – is it stiff enough in these directions while allowing vertical movement?).

[93legendti]

I first saw them a while back on the TitanFlex web page; and found them interesting.

A weight penalty for the front hub in the range of about 100 grams could make it more viable to more riders than full suspension forks, which seem to add considerable weight. Typical weight penalties for many fork types I’ve found were in the 500 to 900 gram range. Being able to use these front hubs with standard forks and frames should also make it more appealing and therefore viable to more riders.

I’ve been meaning to try one for a while but thought they would have limited acceptance for high performance bikes. One concern I had was that as the front wheel moves up and down the caliper brake pads may no longer line up with the rim’s braking surface. Also worth testing is its ability to control front wheel motion in the “roll” and “yaw” directions (i.e. – is it stiff enough in these directions while allowing vertical movement?).
Good questions. You'd think the manufacturer would have addressed the brake pad issue, but who nows?

[RPS]

Good questions. You'd think the manufacturer would have addressed the brake pad issue, but who nows?Somewhere in the literature I read a few years ago I ran into that issue. As I vaguely recall they recommended using rims with wider-than-normal braking surface and suggested adjustment of the pads carefully.

Obviously one way to get around that is to use a disc brake with the wheel predominantly moving perpendicular to the mounting location of the caliper. With the typical mounting somewhat behind and above the front axle the edge of the disc would still move towards the caliper some, so I’m not sure how much clearance they need or how they get it. One down side I see to combining disc brakes and suspension in the hub is that the “reaction” forces from the disc/caliper will affect the load on the hub's suspension asymmetrically.

[Tobias]

Thanks all for the great information.

Cost on a high-end bike is probably secondary, so I’m starting to think that finding a happy medium between weight versus fork travel, complexity, and performance involves tough compromises.

As a strong believer in the 80-20 rule I’d expect initial fork travel does the most good, and that adding more probably has diminishing returns. Assuming all approaches worked equally well (although they rarely do) a hub with a weight penalty of 100 grams and 12 MM of travel would work better for me than a front fork that added 900 grams to provide an MTB-like 75 MM. Unfortunately the simpler designs that appear to weigh less probably don’t perform to the same level.

[RPS]

If anyone is thinking about installing a Ruby – even on a temporary basis – to experience what it’s like to have a suspension fork on a road bike, you may want to consider the following before deciding.

The fork length/height is considerably greater than I expected. My bike went from a level top tube to a slight sloper; and in the process changed the HTA and STA considerably. BBKT height is higher also. For a test or to play with on a temporary basis it’s OK, but to do it right it needs a dedicated frame geometry. And since the Ruby has been out of production for years, that doesn’t make much sense to me.

Considering it’s built much like an MTB fork, fatter-tire clearance is relatively limited. I guess ten years ago the idea of putting fat tires on a road bike wasn’t popular; and since a 23MM clears with ease maybe a 25 or 28 would also work well (as long as you don’t break a spoke during a ride). Besides, the fork suspension should eliminate much of the need for a fatter tire in the first place.

The mounting bolt on a standard front caliper was too long; so I used a rear DuraAce caliper as an easy fix.

I don’t know how long I’ll leave it installed or how well it will hold up over time, but after the initial 100 miles during the last two days I’m sold that a Ruby does some things very well.

[palincss]

Thanks all for the great information.

Cost on a high-end bike is probably secondary, so I’m starting to think that finding a happy medium between weight versus fork travel, complexity, and performance involves tough compromises.

As a strong believer in the 80-20 rule I’d expect initial fork travel does the most good, and that adding more probably has diminishing returns. Assuming all approaches worked equally well (although they rarely do) a hub with a weight penalty of 100 grams and 12 MM of travel would work better for me than a front fork that added 900 grams to provide an MTB-like 75 MM. Unfortunately the simpler designs that appear to weigh less probably don’t perform to the same level.

Here's something to consider: pneumatic tires were originally adopted in order to provide suspension. Unless you've experienced a wide low pressure road tire, you may be very surprised at how effective one can be as suspension. If you're looking for high simplicity, low cost and amazing cost effectiveness, it's a great place to start.

[Tobias]

Here's something to consider: pneumatic tires were originally adopted in order to provide suspension. Unless you've experienced a wide low pressure road tire, you may be very surprised at how effective one can be as suspension. If you're looking for high simplicity, low cost and amazing cost effectiveness, it's a great place to start.What do you have in mind for comparison? Size, pressure, total weight, etc.?

Also, how do you rate/compare the advantage/disadvantage in ride and performance versus a suspension fork -- beyond simplicity and cost you mentioned?

[alancw3]

road suspension fork??? isn't that an oxymoron?

[Tobias]

The fork length/height is considerably greater than I expected.
...snipped....
I don’t know how long I’ll leave it installed or how well it will hold up over time, but after the initial 100 miles during the last two days I’m sold that a Ruby does some things very well.When looking on E-Bay, I found rebuild kits that included springs in different stiffness. Noticing your picture above shows the fork more extended than the picture posted by Elefantino, I'm wondering if there were different length springs; or stiffer springs that don't compress as much. :confused:

How much longer is it? Any comparison versus tire pressure? What's to like, or not?

[Tobias]

road suspension fork??? isn't that an oxymoron?Is it any more than fat low-pressure tires? Going back many decades tires were bigger and lower pressure, but then suspension was around 100 years ago.

I think it comes to down to weight and simplicity. No one wants a heavy bike for the sake of weight, or a bike that requires more maintenance.

[RPS]

When looking on E-Bay, I found rebuild kits that included springs in different stiffness. Noticing your picture above shows the fork more extended than the picture posted by Elefantino, I'm wondering if there were different length springs; or stiffer springs that don't compress as much. :confused:

How much longer is it? Any comparison versus tire pressure? What's to like, or not?Since I bought it used on E-Bay I don’t know what spring rate it has. For that matter, I don’t know if it was modified with something custom – although I doubt it has.

I just found instruction on the WEB to take it apart for maintenance and service so I’ll eventually try to figure out exactly what’s in it. For now I’m content to ride it without more preconceptions.

It’s about 3 CM longer before I get on the bike. I figure that when loaded it changed the angles by about +/- 1.5 degrees. No doubt that’s significant but I can deal with it as a test. The longer rake helps keep trail closer to original. I don’t know yet why the fork is that long because when fully compressed the tire doesn’t come close to bottoming out.

I can’t judge performance based on such limited riding, but can share first impressions. When standing I can feel a little bounce at higher cadence (by my standard which isn’t extremely fast), and I’d compare it to the bounce I get on my trainer when the 23 MM front tire gets down to between 20 to 30 PSI (more or less – rough estimate). In the sitting position -- or while standing at lower climbing cadence -- I haven’t noticed any movement due to pedaling.

It handles bumps incredibly well. The bigger the bump the bigger the difference -- like over rough tracks. Not to like: Complexity, MTBish looks, added weight.

I’ll know more in a couple of weeks when I go to the Hill Country and ride it on rougher roads and have a chance to climb and descend steep grades.

[Gothard]

About that Ruby: I have 2 on the shelf (for sale cheap, btw) and 3 Roubaix. The Rubys have much more offset than the Roubaix originally on the bike (around which teh frame was in fact built). What offset does yours have? more or less than the std fork?

[palincss]

What do you have in mind for comparison? Size, pressure, total weight, etc.?

Also, how do you rate/compare the advantage/disadvantage in ride and performance versus a suspension fork -- beyond simplicity and cost you mentioned?

One comparison point I have right in my basement is a rigid bike with 38x650B tires at 50psi compared with an AM-series Moulton with full suspension.

The 650B bikes don't boing at all. Climbing out of the saddle feels like a regular bike. Climbing out of the saddle with the full suspension Moulton causes the bike to bounce up and down; the trick is to get in sync with the bounce, otherwise you flop all over the place - kind of a velo version of V Fib.

The ride with low pressure 650Bs on coarse surfaces like chip seal is plush, more so than the Moulton, I think.

The Moulton fork wins on manhole covers (but watch out for the smack in the butt from the rear suspension).

On really big hits, the Moulton fork bottoms out (at least, for me, with the spring I have) so they both it hard, but there's not much give from those 17x1 1/4 tires run up at customary pressures compared to the 50psi 650Bs, so I'd say 650B wins.


Plush fat low pressure tires generally don't feel fast, although they can be - in fact, the best of them have rolling resistance comparable to 23mm racing tires, and on some surfaces they're faster than narrow high pressure tires. They will weigh more than narrow tires, of course, but the good ones don't weigh as much as you'd think, and not nearly as much as a suspension fork.

So overall, there's not much of a performance penalty for wider and lower pressure, and with some tires, there's no penalty at all.

[RPS]

About that Ruby: I have 2 on the shelf (for sale cheap, btw) and 3 Roubaix. The Rubys have much more offset than the Roubaix originally on the bike (around which teh frame was in fact built). What offset does yours have? more or less than the std fork?It looks like about 45 MM to me, but it's hard to measure accurately. That makes it slightly more rake than the fork it replaced.

Gothard, do you know how many different spring stiffnesses were offered for the Ruby? Or how much preload is recommended? BTW, how much offset do the Roubaix have; and were they and the Ruby offered with different offset/rake?

[Gothard]

No idea about different stiffness in the Ruby. Only got the forks used.
I did not measure preciely the offsets, only to confirm that the Ruby has more than the Roubaix, which is the original fork to my bike.

[christian]

Not that I think stiction is a major issue on bicycle forks, but for a non-racing application, I think a leading link front suspension would be vastly simpler than a telescopic fork, especially for low-travel applications (which is everything on a road bike). Have a look at sidecar-specific motorcycle tugs or old Honda Cubs and scale it down and you'll get a pretty good idea... The Moulton AM design looks a bit wacky but is a pretty standard leading link.

[RPS]

Not that I think stiction is a major issue on bicycle forks, but for a non-racing application, I think a leading link front suspension would be vastly simpler than a telescopic fork, especially for low-travel applications (which is everything on a road bike). Have a look at sidecar-specific motorcycle tugs or old Honda Cubs and scale it down and you'll get a pretty good idea... The Moulton AM design looks a bit wacky but is a pretty standard leading link.Christian, I think not only simpler but maybe lighter as well.

Regarding the possible adverse affect of stiction I like to distinguish between road and mountain bikes. It isn’t a major problem on a mountain bike because the primary reason for the fork is to absorb large bumps, so a little static friction fighting initial suspension movement isn’t much of a problem.

On a road bike one could argue whether reducing road buzz is not as important – or more so – as minimizing the effect of an occasional impact. As with a mountain bike, a road fork’s ability to handle large bumps won’t be affected much by stiction. However, any significant friction will transmit too much of the low-amplitude high-frequency vibration riders experience on rough pavement (which could be experienced for hours at a time).

For that reason I think eliminating stiction is far more beneficial on a road suspension than on MTB. And for that a leading link fork may do a good job.