Fork ReRake

[David Riggs]

Alex Wetmore of Bicycle Quarterly showed how to rerake a fork on his blog, which is now suspended for some time. He seems to have just bent them and then rode them. Looking for advice on rerake as local bike shops in Seattle are not too interested without loads of hemming and hawing, a lecture at worst. Anyone done this?

[CMR]

I would ask a frame builder around you their thoughts, It varies by individual fork and how much change. Frame builder > shop mechanic for sure though!

[desmond...@gmail.com]

Cost a shop charges to do that vs new made one??

Sent from my iPhone

On Aug 31, 2016, at 13:40, David Riggs <ether...@gmail.com> wrote:

Alex Wetmore of Bicycle Quarterly showed how to rerake a fork on his blog, which is now suspended for some time. He seems to have just bent them and then rode them. Looking for advice on rerake as local bike shops in Seattle are not too interested without loads of hemming and hawing, a lecture at worst. Anyone done this?

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.
To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

[William Lindsay]

If I were in the Seattle Area and I wanted to pay somebody to re-rake my fork, I would curse to the winds that Elliot Bay Bicycles is closed.  Davidson used to share the space and I saw their fork rake jig with my beady little eyes in the back of the shop.  Can you reach out to Davidson and see if they take on work of that kind?  E-mail Jan to recommend local framebuilders who take on repair jobs.  

Re-raking a fork is extremely easy provided you have the tooling to do it.  A typical bike shop does not have that tooling.  When Shop X is not set up to provide a particular service, the correct message to the customer is "Sorry, we cannot perform that service for you".  It's lame when they cover that up with "You shouldn't want to have that job done".  

Doing the job is easy but building the tooling is the hard part.  Building the tooling for a completed fork is harder than building the tooling to consistently bend blades one-at-a-time.  If you have zero money and tons of time and tons of tools, then making your own tooling could be an entertaining way to spend your free time.  If you have some money and less time, it's way more efficient to find somebody with the tooling and pay them to do the job for you.  I'd bet a dollar that you won't find a bike shop with a fork raking jig, but most any framebuilder who makes forks will.  Find a framebuilder who likes doing repair work.  If it were me, here in the East Bay, I would go to Ed Litton.  

Bill Lindsay

El Cerrito, CA

[Alex Wetmore]

All of the content from my blog is still there at http://alexwetmore.org/.  It is a static copy, so search doesn't work, but you can do a site specific search in Bing or Google to find what you'd like.  I'm guessing that "site:alexwetmore.org fork re-raking" would find what you want.

I didn't just bend and ride them, the forks were always aligned afterwords.  When I wrote the blog entry (probably 9 or 10 years ago) I was doing it with a VAR fork alignment tool (Park and Stein also made them).  For the last 7 or 8 years I've had a fork and frame alignment table at my disposal and have always done it using that.  

Re-raking requires tools that few bike shops will have at their disposal.  If you are re-raking by extending the bend in the fork blade (as opposed to bending the entire fork blade from the crown) you need access to fork bending mandrels in a variety of radii to match what was already there.  The shops that do have these tools would probably rather build you a new fork, which is ultimately usually the safer and better option.

alex

---

From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of David Riggs <ether...@gmail.com>
Sent: Wednesday, August 31, 2016 1:40:53 PM
To: 650b
Subject: [650B] Fork ReRake

 

Alex Wetmore of Bicycle Quarterly showed how to rerake a fork on his blog, which is now suspended for some time. He seems to have just bent them and then rode them. Looking for advice on rerake as local bike shops in Seattle are not too interested without loads of hemming and hawing, a lecture at worst. Anyone done this?

--

[Mark Bulgier]

David Riggs wrote:

> Looking for advice on rerake as local bike shops in Seattle are not too interested [snip]

Have you tried Davidson, in Fremont?  They are experts at raking and have done plenty of re-raking.  I know because I used to work there.  I don't know how they feel about working on other people forks these days (might be too busy or have other concerns), but you should ask.

I assume you want to add rake?  That requires a form to bend them over.  If you want to decrease the rake, a big rubber mallet will suffice.  And no, I'm not kidding, I have done it plenty and it works perfectly.  Requires some degree of skill and experience though, so I'm not sure if that's something your average home handyman should try for himself.

If you are of much more than average degree of "handy with tools" then you might consider building your own raking bender.  There is a set of instructions here: http://www.instructables.com/id/Easy-Fork-Blade-Benders/
The resulting bender is much like the one Alistair Spence made for himself some years ago: https://flic.kr/s/aHsjnqErZQ

Or for the "git 'er done" or less-patient types, consider something like this: 

In general re-raking can be done without totally ruining the paint, but I have seen exceptions where the paint flaked off.  Same with chrome -- risky because if the chrome cracks and/or flakes off, it's expensive to fix.  Some slight damage to paint or chrome is almost inevitable.

Mark Bulgier
Seattle

[desmond...@gmail.com]

Well I've recommended " Davidson shop to many of these guys, they built my first one in 1991- an many since. Alway meet with assault of to much money they don't understand what I'm doing.. Good to hear from one of the best builders around . Cheers Allan  

Sent from my iPhone

--

[nm matt]

i reraked a mid '80's trek fork with a pretty crude shop made jig. an alignment touch up post bend and it was good to go. you shohld also consider where you are adding rake, as this will your affect axle to crown distance, and by extension seat tube angle. if you have your saddle slammed back on its rails, a rerake may necessitate a seatpost with more setback. good luck! have you contacted cyclefab? they are in seattle i believe.
best, matt b

[Mark Guglielmana]

Alex's blog is a gold mine of information. It was one of my inspirations to make my own jig, which I named the Babe Ruth of fork rerakers:

On Wednesday, August 31, 2016 at 2:11:54 PM UTC-7, David Riggs wrote:

[Ken Freeman]

I've talked to a lot of builders and shops about re-raking forks, and I even had rake removed from a Trek fork, by a "famous maker."  When I wanted to go low trail, I was met by a few objections:

You'll change the ride hight in the front, might lose tire clearance.

The steel will be weakened by the bending (cold-setting, you know).  The blades were cold-set at least once when the fork was made, and may have been cold-set again if they needed additional alignment.  To re-rake the fork by an excellent pro with correct tooling, may be one more cold-set, or it may be several if the person over-bends it.  Think of breaking a paper clip by bending it sharply back an forth.  

The builder and the shop are worried in part about damaging the customer's goods in a way that would detract from safety, and most likely additionally becoming legally liable for damages in case of a dangerous failure.  If I was a shop, I wouldn't do it.  

--

You received this message because you are subscribed to the Google Groups "650b" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 650b+unsubscribe@googlegroups.com.

To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

--

Ken Freeman
Ann Arbor, MI USA

[Mark Guglielmana]

Ask enough people, you'll get a lot of opinions either way. In this case, we're discussing something that few framebulders ever do - rerake. So let's discuss this. I apologize in advance for the length of this post, I hadn't the time to make it shorter. 

Any frame builder that makes a steel fork with offset (rake), bends it on a mandrel. This is almost always done prior to brazing/welding up the fork. It is done as a cold set. I can imagine this is why some are hesitant to rerake, since you're doing it with the fork "all assembled". In reality, however, a proper mandrel, or form, holds the fork above the dropout, and applies forces on neither the crown nor the dropout. It doesn't take a mechanical engineer (which I happen to be) to understand that the highest stresses on the fork while riding are at the dropout and the fork crown (and the steerer, but it's not involved in reraking unless you're doing it wrong). Reraking on a proper jig applies force to neither

The paper clip analogy isn't quite correct if you're reraking a fork properly. Imagine a fork being made, from scratch, starting with a straight fork blade (as they all do). Say your goal is to rake to 65mm (typical low trail target for 73 degree head tube angle). Typically I see vintage bikes with rakes of 45-55mm prior to reraking. So you start with a fork blade with zero rake, and it bends along the curve on the mandrel to 45, past that to 55, and you stop at 65. Whether you've raked the fork today to 45mm, then tomorrow, next week, next year, or a few decades later you continue to 65, you've cold set the steel to the same parameter. If you've ever raked or reraked a fork, you'll know that you're starting the bend nearer the dropout end, and as you create more rake, the bend continues up the fork blade-you're not bending the fork more where it's already bent, you're mostly bending a section that was previously straight. The curved mandrel supports the "already bent" portion, and forces are applied progressively up the fork blade. In essence, you're limiting the amount of bend per length with the mandrel. 

To address the "fork will be weaker" claim, there is no one pararmeter that you can claim for steel, or any metal for that matter, that tells you everything you need to know about the material. To keep it simple, however, here are some things to consider. Study a stress-strain diagram, and you'll realize that cold setting increases the yield strength locally (where the fork bends) - one "work hardens" a part, not "work softens". But what you're also doing is using up some of the toughness of the material - looking at the stress-strain diagram again, you're moving to the right of the plastic deformation part of the curve and towards the failure point - you're using up some of the "life" of the material, like a cat using up one it's "9 lives" as a simple analogy. Note that the stress-strain diagram is valid only for a very localized area of the fork - it says nothing about the entire fork as a structure. Going back to the previous paragraph, if you're using a proper mandrel, you're not rebending any material, you're bending an area that was once straight. If one were using a very tight radius mandrel to rerake a fork that had a more gradual bend, this isn't quite true. But there are plenty of vintage Rene Herse/Alex Singer/et al bikes with tight bend "french" forks that are still on the road, and I'll go back to my previous statement - it doesn't matter when the fork was raked. 

As far as dropping the front end and losing tire clearance, these are technically correct statements. Dropping the front end in and of itself is insignificant - only a few mm typically. Dropping the front end does change the head tube angle, which is significant if you're reraking for low trail. Go to a trail calculator online and you'll find that they don't account for this (and they can't), and you can find yourself going for a particular trail number and "over-raking" - and that's not the intention of the calculator. Tom Matchak wrote an excellent article on this. I measure the head tube angle before and after reraking to make sure I'm hitting my target trail. I have enough data points on my fork reraker that I have a model for how much the head tube angle changes for every mm of additional rake. Every mandrel shape will have it's own model to determine the head tube angle change. Before I had this model I started off by using the "method of halves", adding only half the amount of rake that the calculator said for the starting head tube angle, putting the fork back in the frame and wheels and remeasuring the head tube angle, using this head tube angle to recalculate the rake, iteratively approaching the target trail that way. So, yes, you don't want to rerake by bending back and forth, so if you're interested in having this done, have someone with experience do it. 

The front end does drop, which affects the head tube angle. I suppose an extremely sensitive Merckxian rider would notice a change in riding position, but wouldn't it be a simple matter of raising the stem a few mm to account for this? 

When deciding on reraking, I take into account the tire the bike will be using, whether it will be using fenders or not, fender clearance, etc. Since the trend is to put 650b tires on vintage bikes that were designed for 27"/700c, the smaller diameter tire typically gives plenty of clearance. The clearance loss, BTW, is typically a few mm. If the fork doesn't have room to account for this, pass. 

The number of shops that are equipped to do this work is extremely small. The amount of tools vs the amount of business wouldn't pay for it. Most that would do the work have a resident framebuilder. Like most anything, if you don't know what you're doing/don't have the proper tools, don't try this at home. It took me months of studying the subject, experience riding a bike that had been reraked by some guy in Connecticut (who shows up on this forum now and then), and watching others do it (shout out to Star at Norther Cycles) before I made my own jig and tried it on my own bikes. You also need dropout alignment tools (more common), and a method to determine dropout center (less common). 

Not doing it because of FUD is one thing. I hope this doesn't stop someone from understanding what's involved, and if lower trail is desired on a frame you currently own, finding someone competent to do the work and making a rational decision to rerake, or not. 

On Saturday, September 3, 2016 at 6:28:26 AM UTC-7, Ken Freeman wrote:

I've talked to a lot of builders and shops about re-raking forks, and I even had rake removed from a Trek fork, by a "famous maker."  When I wanted to go low trail, I was met by a few objections:

You'll change the ride hight in the front, might lose tire clearance.

The steel will be weakened by the bending (cold-setting, you know).  The blades were cold-set at least once when the fork was made, and may have been cold-set again if they needed additional alignment.  To re-rake the fork by an excellent pro with correct tooling, may be one more cold-set, or it may be several if the person over-bends it.  Think of breaking a paper clip by bending it sharply back an forth.  

The builder and the shop are worried in part about damaging the customer's goods in a way that would detract from safety, and most likely additionally becoming legally liable for damages in case of a dangerous failure.  If I was a shop, I wouldn't do it.  

On Thu, Sep 1, 2016 at 9:27 PM, Mark Guglielmana <mark.gug...@gmail.com> wrote:

Alex's blog is a gold mine of information. It was one of my inspirations to make my own jig, which I named the Babe Ruth of fork rerakers:

On Wednesday, August 31, 2016 at 2:11:54 PM UTC-7, David Riggs wrote:

Alex Wetmore of Bicycle Quarterly showed how to rerake a fork on his blog, which is now suspended for some time. He seems to have just bent them and then rode them. Looking for advice on rerake as local bike shops in Seattle are not too interested without loads of hemming and hawing, a lecture at worst. Anyone done this?

--
You received this message because you are subscribed to the Google Groups "650b" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

[desmond...@gmail.com]

Mark you bring up some great points, But can I get it Blue?

Sent from my iPhone

[Mark Guglielmana]

With a french rake, non, but bleu can be done.

;-)

[Eric Keller]

Mark,
Are you offering your services for re-raking?

I've always figured it was probably safe to do, but I still wouldn't
do it. Too many complications and there are a lot of crummy forks out
there, why assume the liability?
Eric Keller
Boalsburg Pennsylvania

[Alistair Spence]

It's been a while (maybe 9 or 10 years?) since I re-raked a fork. I did maybe eight or so re-rake jobs, for myself, and for friends, before I decided that it was ultimately better to build a new fork. I remember adding rake to a fork for Mark Vandekamp, for a story he was writing for (Vintage) Bicycle Quarterly. Iirc it was a unicrown fork for his Dave Levy built Ti Cycles frame. I worked, I got the required increase in rake but the pressure required to eke out the final few mm's was quite large (due to the large radius mandrel) and I was concerned at how much pressure the bending roller was putting on the back side of the fork blade.

What I found to be quite important was the shape of the mandrel being used for the re-raking job, compared to the shape of the mandrel that was used to originally rake the blades. Often, the radius/geometry of the original mandrel is not known, but by looking at the shape of the blade can give some good clues.

Also, I found that certain radius mandrels are somewhat limited in terms of how much rake they can ultimately add. The 10" radius Hammill Eng. mandrel from Nova that everyone used for years is good for typical higher trail (lower rake) bends, but I found it less than ideal for the tight/low lower trail (ie. high rake) bends that seem to give the best "tip action" (ie. attenuating the smaller bump forces typically encountered during normal road riding). I found that what was needed for that was a mandrel that had a radius more in the 5" - 6" range.

Taking a fork with a traditional 45mm - 50mm rake that has the long gradual curve that goes (typically) half way up the fork blade (presumably raked on a larger radiused mandrel), and then using a mandrel of smaller radius to add rake and get a more "French" look to the curve ends up looking a little off to my eye but it's not just the aesthetics that are troubling. The point at which the bend transitions from one radius to another could possibly cause a stress riser.

Putting a second bend over the top of a first one isn't necessarily a deal breaker in my mind, but if you think about what's going on at a molecular level in the metal it does give pause. Deforming metal plastically involves sliding the layers of atoms within the metal lattice over adjacent layers. As you do this, the discontinuities that exist within the metal start to build up at boundary layers. This is basically what increases the yield strength and reduces the toughness. When you get a large enough accumulation of discontinuities in one spot, you get crack nucleation and ultimately failure. 

It's one thing to rake a fork on the same mandrel and get a smooth controlled bend. Re-raking, and potentially subjecting the blade to being re-shaped on a different radius mandrel is, I think, a little risky, and a touch crude.

Yes, it can work and yes, I've done it, but knowing what I know now I wouldn't do it again. The possibility of liability issues that might arise in the future is too risky in my view.

In the end, it's up to the individuals involved, especially the person riding the fork in question.

Alistair Spence,

Seattle, WA.

To unsubscribe from this group and stop receiving emails from it, send an email to 650b+unsubscribe@googlegroups.com.

To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

--

Alistair Spence,

Seattle, WA.

[William Lindsay]

Regarding "the liability issue". Can anyone share any anecdote of a rider who had a re-raked fork fail? More to the point, can anyone share an anecdote of somebody being sued after reraking someone else's fork? I've never heard of either case. I imagine it may have happened and would be curious to hear the tale.

Bill Lindsay
In very litigious
El Cerrito ca

[Alistair Spence]

From the few data points that I have personally, I can say no. No failures as a result of re-raking. None that have been reported back to me anyway.

One bad experience I had was re-raking the chromed fork of a friend. In hindsight the curve of the mandrel was not a good match for the curve of the already raked blade. First bad thing that happened was that the plating on the back side of the curved part of the blade cracked and split open leaving a good three inches or of exposed metal. 

I continued on (with the owners permission), trying to add more rake, but only succeeded in kinking the blade quite badly, trashing the fork.

No idea if the fact that the fork was chromed had anything to do with this. I suppose it could have. Improper plating can result in hydrogen embrittlement (if the hydrogen generated by the plating/electrolysis process isn't baked out of the metal before it has the chance to become absorbed into the crystalline lattice of the metal) but I don't know if that was a contributing factor here.

Anyway, back to the issue at hand. I feel that re-raking, if done at all, is a "framebuilding" operation and should be done by a framebuilder who carries the necessary liability insurance. Last time I checked the entry level cost of that was around $2000 per year.

Alistair.

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+unsubscribe@googlegroups.com.
To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

[Nick Favicchio]

I've had a fork reraked and I've tried very hard to kill that fork and myself with the bike and fork and I've failed. At both. The fork in question is made out of prolly hi-ten? Dunno. Was raked too much then un(de?)raked by a local weirdo. Who later built me a dope frame and fork.

Do it. Listen to Mark Guglielmana. People with silly sounding (looking?) Italian names know what's up.

Loosing axle to crown distance is real tho. Reraking is also a good option when looking to match fender lines front and rear on older bikes with LOADS of fork crown clearance but less at the brake and chain stay bridges in the rear.

Also does something to handing. Something about "trail" was it? Yea.

Nick "Not Biased" Favicchio

[Mark Guglielmana]

Damn, Nick, you mean all I had to do was be born with a funny Italian name, eh, Favicchio? 

--
You received this message because you are subscribed to a topic in the Google Groups "650b" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/650b/UVPj3XXHhnU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to 650b+unsubscribe@googlegroups.com.

To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

--

Mark Guglielmana

[Nick Favicchio]

All in the name. All those years of engineering knowledge and experience are just icing. You had it all along.

[satanas]

The first decent frame I had was of 531, with fork blades of similar shape to the Toei ones. It started out with ~40mm rake but I eventually re-raked it to about 55mm. After that the fork flexed a lot more down near the dropouts, not just over bumps but also when standing, which I found a bit disturbing. In the end the rake was reduced a bit and all was well for quite a few years afterwards, ie no failures or problems of any kind.

So, IMHO, if one isn't worried about being sued - in the above case it was mt frameset and I did the bending - then I see no need to be too paranoid, provided one proceeds with care. Note that I was working in a bike factory at the time and had access to framebuilders' input and tools.

Later,
Stephen

[Darrell Goodwin]

I re-raked a couple of forks on the cheap by building my own jig using an axle mount (like you might bolt to a truck bed) and some plywood guides cut to the desired radius, factoring in springback.  I mounted the jig in a bench vise, and used a donor fork as a first test. I was pleased enough with the results to re-rake a decent quality fork with good results.  Just be sure you anticipate the reduction in axle-to-crown length after it's re-raked!

[Fausto Copious]

I happened upon this group thinking I was in the Classic Rendezvous group.   But the subject interests me so I joined.   I am Bob Freeman, Bill Davidson's partner for 31 years at Elliott Bay.   He didn't just share space, he was co-owner of the shop.   Yeah, the closing wasn't really our idea either, though I did intend to retire in about a year anyway at age 66.   Seattle just made it impossible for us to continue, with their mission to build build build, and no plan to do anything about traffic or parking.   People just wouldn't brave the trip any more, and we couldn't exist on walk-in inner tube sales.   Heck, I hated going in myself.   Now I go in to Seattle maybe once or twice a month, and try to combine visits to Bill, the powder coaters, chrome platers, and other places where I can only get work done there.   Otherwise, I stay away.

While I don't have any of our frame shop stuff at home, I do have a couple of crude fork tools.   One to re-rake a fork and one to align it.   Takes me a bit longer with these than with the ones from the shop, but I can do it.   Last night I straightened out a badly bent Jack Taylor fork.  It had been front-ended and bent back at the crown, and was also off to one side.   Came out very nice.    I also re-raked the fork that came on my Bernard Carre.   It had a head angle of 70.5, and rake of about 38 mm, producing 80 mm of trail.  I figured it needed to be about 55 mm of rake to make a nice normal trail (for a road bike) of 58 mm, so I bent the blades myself using a single blade bender that an old friend and former amateur frame builder gave me.  I recognized that by doing so it would also shorten the fork, and put a slope in the top tube, but I was willing to put up with that for a better ride.  It also steepens the head angle, which also goes in the right direction for less trail.   I couldn't take my hands off the bars before, and now it rides very nicely no hands or otherwise.  You don't really notice the top tube slope unless it is against the horizontal siding of my house.    Take a look.

By the way, I took the Carre fork to Bill, and he just said, nah, ride it the way they made it.   He's not much interested in doing any repairs these days.  

I also changed the rake of one blade on my Pat Hanlon as the wheel did not sit centered, and probably never had, but I should warn you, when you do this to a fork with chrome, you will likely crack the chrome, and I did.

Some pics of three of our 650B bikes, for your enjoyment

 https://www.flickr.com/photos/8379107@N03/albums/72157662078495374

https://www.flickr.com/photos/8379107@N03/albums/72157667836061511

https://www.flickr.com/photos/8379107@N03/albums/72157649833683259

I had my first 650B bike in 1981 by the way, a converted Rudge Whitworth.  It was my around town bike at the shop, and I still have it.   I also had this Jack Taylor made in 1983

https://www.flickr.com/photos/8379107@N03/sets/72157622569187171/  Those are the first lowrider racks Jack ever made.  

regards

Bob Freeman
North Bend WA

[Alistair Spence]

Hey Bob,

great to see you here, welcome. I hope you stick around and take the time to share more of your cycling knowledge when you have the time.

Cheers!

Alistair Spence,

Seattle, WA.

--

You received this message because you are subscribed to the Google Groups "650b" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 650b+unsubscribe@googlegroups.com.

To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

--

Alistair Spence,

Seattle, WA.

[Mark Guglielmana]

On Sunday, September 4, 2016 at 3:43:52 PM UTC-7, satanas wrote:

The first decent frame I had was of 531, with fork blades of similar shape to the Toei ones. It started out with ~40mm rake but I eventually re-raked it to about 55mm. After that the fork flexed a lot more down near the dropouts, not just over bumps but also when standing, which I found a bit disturbing. ...

That's what I would call a feature, and I'm not being sarcastic. Straight forks lack much of the ability to act as a shock absorer, the more rake, the more flexible, the more the front wheel follows the terrain rather than bump up and down.  

[Mark Guglielmana]

Hi Bob! Good to see you here. You warned me about riding with Matt P., it's true, he eats rocks and craps sand. He came down to do a forestry road ride from Forest Grove to Tillamook several weeks ago with some fellow Portlandiers, he was nice enough to wait at the top of the long climbs for us. I was riding 54mm tires, he was on 35's, so I was able to keep up with him on the downhills. One of these days I've gotta make it up to North Bend for a ride with you guys.

[Eric Keller]

On Mon, Sep 19, 2016 at 7:39 PM, Mark Guglielmana
<mark.gug...@gmail.com> wrote:
> Straight forks lack much of the ability to act as a shock absorer, the more
> rake, the more flexible, the more the front wheel follows the terrain rather
> than bump up and down.

Using the same level of rigor as the above statement, I think the
difference is about 10 percent. All things being equal. Of course,
with raked blades you can get more rake and more compliance if you
like.
Eric Keller
Boalsburg, Pennsylvania.

[Mark Guglielmana]

Jan discussed this in the latest issues of BQ, no need to repeat here.