Re-raking an existing fork

[Ty Smith]

I've got an idea to improve my existing bike before taking the plunge for a custom bike and I wanted to get the group's advice.

I have a Salsa Casseroll. Basically an "off-the-rack" Rando bike that I got a year and a half ago when I was first dipping into randonneuring. In the next year, I think I want to go 650B, either a Pelican or Boulder. Still trying decide that, and am open to other options, but those are my main contenders.

In any case, toe-overlap is driving me crazy on this bike. Evidently it is normal for a 700C bike, but I hate it! My cargo bike, with 26" wheels and my folding bike with 16" wheels, don't have it at all.  The main area I have problems with this is in doing a track stand at lights. I'm just in the habit of doing it with my cargo and commuter, so it is off-putting, to say the least, when I try it on my Salsa and hit my toes.

So I thought that I would get the existing Salsa Casseroll fork re-raked. This would accomplish three things. 1. Get ride of the toe-overlap, or at least reduce it. 2. Give the bike a more  low-trail feel, which would be better with the handlebar bag. 3. Make me happier until I can get a 650b bike.

So is this feasible? If so, anyone in the Bay Area that could do it? Recommendations either way?

Thanks in advance!

Ty

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http://thecrazyrandonneur.wordpress.com/

[Metin Uz]

Ty,

I would discourage you from re-raking the original fork in order to reduce toe overlap. As little as 5mm change in fork rake will affect the handling, and you may need quite a bit more to eliminate the overlap, especially if you are using fenders. The head tube angle on your bike is surely not designed for a highly raked fork.

I have two suggestions that could help. First, you could learn to deal with it. I have significant overlap on my fixed gear with fenders. I have learned to synchronize my tight low-speed turns so I straighten out as my outside foot gets to the front. Another solution is to clip out and put your toe over the pedal spindle. You only need to do this on one side (outside pedal).

With good track stand technique, you should not need to sway your front wheel to both sides. Most people like to have their dominant foot front on a track stand, and the curve of the road determines whether you point left or right. As long as you point in the same direction as your forward foot, you will not have a problem with toe overlap. So, practice using the "un-natural" foot forward when you track stand on your other bikes.

You could also do a 650B conversion on your Salsa. It may or may not be practical with bottom bracket height, etc. Also this may not help if you use wide tires and fenders, as you will be back to square one.

--Metin

[Ty Smith]

Hey Everyone!

Got a couple good reccomendations and have already talked to a builder who thinks it can be done. Just need to check a few details, but tentativly looking good so far

Thanks!

Ty

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http://thecrazyrandonneur.wordpress.com/

[Len B]

I went from a 376mm axle to crown 45mm rake carbon fork to a 396mm 48mm rake 4130 steel fork on my Jamis Sputnik track bike after a crash broke the steerer tube.  That change slowed down the handling, not so twitchy anymore, and let me run a front fender again.

While I havent run the numbers to figure the magnitude of this change, I'm of the opinion that one can get used to a large range of different handling characteristics in bikes so long as they dont pass beyond extremes and maybe a simple fork swap might be an answer, pushing the front wheel away and raising up your bars (and standover, a bit) to lose the overlap.

Len

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[Greg Merritt]

> I'm of the opinion that one can get used to a large range of different handling characteristics in bikes so long as they dont pass beyond extremes...


I have test-ridden a mismatched frame & fork from a pair of otherwise
just-fine cross bikes, and the mixed set was dangerously unridable.
As you turned, particularly at lower speeds, it viciously insisted to
turn even more tightly than you wanted, and the more it got its way,
the more fiercely it would insist to keep making it worse!

So, you never know...

-Greg

[Darell (EVnut)]

> I'm of the opinion that one can get used to a large range of different
handling characteristics in bikes so long as they dont pass beyond
extremes...

Greg wrote>

As you turned, particularly at lower speeds, it viciously insisted to turn
even more tightly than you wanted, and the more it got its way, the more
fiercely it would insist to keep making it worse!

I'm going to have to assume that anything approaching 'vicious' handling
would fall into the "passing beyond extremes" category.

- Darell

[Ty Smith]

Thanks Metin,

Good point regarding the head tube angle. I read on Jan Heine's blog some suggestions mentioning the head tube angle needed. I was pretty sure I was ok, but I emailed him with what I found on the Salsa site for his advice and he was kind enough to reply:

"55 mm trail works really well. Good thing you start with a 73° head angle. Make sure you have enough fender clearance - the crown-to-hub distance will get smaller."

I still need to check that, as well as make sure my brakes have enough adjustment after the re-rake.

Oh, and my first thought was 650B conversion. Sadly, after doing some measuring, I found my low bottom bracket makes this not feasible. I also wanted to go up in tire width to 42's, so that was disappointing. That will have to wait until I do get a 650B bike in a year or so.

Again, going to low trail for me is not simply to eliminate toe overlap, but to give the bike better handling characteristics with a loaded handlebar bag. I think this will do the trick.

Thanks also for the track-stand tips! I'll try them!

Ty

[Jim G]

This is very doable.  Just be sure you use a large-radius bending mandrel so that you don't shorten the fork's axle-to-crown distance too much (and thus cause your brake pads to misalign with the rim).  

From [http://salsacycles.com/bikes/casseroll_double] -- the head-tube angle of your bike should be around 73 degrees (depends on size), which is good.  The fork offset is 45mm (again depends on size, smaller frames may be 50mm).  Using my trail calculator (assuming a 35mm-wide tire) gives you 60mm of trail [http://yojimg.net/bike/web_tools/trailcalc.php?ha=73&fo=45&bsd=622&tw=35]

For low-trail handling with a front handlebar bag, you want ~40mm of trail.  If you increase your fork's offset by 15mm to total 60mm (incidentally, the same as a BDB Pelican), you'll end up with 44mm of trail [http://yojimg.net/bike/web_tools/trailcalc.php?ha=73&fo=60&bsd=622&tw=35].

See also Alex Wetmore's blog entry "Re-raking forks for low trail" [http://alexwetmore.org/?p=473] 

and framebuilder Tom Matchak's article "Fork Reraking and Head Angle Change" [http://phred.org/~alex/bikes/Fork%20Re-raking%20Summary.pdf].  Another bit of information: [http://www.point83.com/forum/viewtopic.php?t=3838]

I've never done this personally, but I am eager to try.  I have a conduit bender which I think would work well for bending the fork blades -- the hard part is getting the fork realigned afterwards.  Box Dog Bikes have a Park fork alignment gauge and can do some bit of alignment (they straightened a slightly tweaked fork for me recently) -- but what you really want/need is a surface plate to fixture the fork and an accurate way to measure the fork blades relative to it.

Alternatively, you could try one of these Electra forks, which I think are offset to some big amount like 80mm.  They'd probably put your trail into the 20-30mm range.  But they're only $50!  [http://store.electrabike.com/eSource/ecom/eSource/TICINO_LUX_CHROMOLY_STEEL_FORK__Polished_Silver__1_1_8_/i_0_0_/_750005.aspx]

-Jim G

On Tuesday, April 30, 2013 9:56:54 AM UTC-7, Ty Smith wrote:

[Jim G]

Oh, which version of the Casseroll do you have?  The 2012 model has a front rack, cantilever brakes, and a curved fork w/395mm A-C: [http://salsacycles.com/bikes/casseroll_2012]

The Casseroll Double has a straight-blade fork that's only 383mm A-C, caliper brakes, .and slightly different geometry:  [http://salsacycles.com/bikes/casseroll_double]

-Jim G

[Ty Smith]

Just got my fork back from Paul at Rock Lobster and had it put back on my Casseroll by Kevan at huckleberry Bikes. So far, so good! The bike went from 54 trail to 42. To the untrained eye (mine) it looks perfectly normal. The paint was not damaged by the re-raking. Paul is awesome!

Here are the stats, Before and After:

Head tube angle 73 degrees
Fork offset was 50mm
Bead-seat diameter 622mm (700c)
Old trail 54 mm

Head tube angle 73 degrees
Fork offset changed to 61.5mm
Bead-seat diameter 622mm (700c)
New trail 42mm

I had actually emailed Jan Heine with my bikes stats after I had read a blog post from him on the subject. He said the head tube angle was ideal for this project, and with encouragement from other SFR members, particularly Jim G., I took the plunge.

I've only been able to ride a few miles on it, but feels great so far. No toe overlap at all now, corners beautifully and holds a straight line very nicely indeed. I'm going to do a wee bit of climbing tomorrow to really put it through its paces.

Oh, and I also got a brand new Rivet saddle from Deb. Feels great already. More on that another time.

Ty

[Doug Williams]

Did your axle-to-crown/tire clearance change noticeably?

[Ty's Gmail]

It did change a little. Sorry, but I didn't measure. The brakes needed to be adjusted a little bit. 

The clearance to the tire is less than it was.  The fenders still fit, but the stays had to be nearly maxed out. 

Currently I am running passella 32's. The bike has clearance for 35's with fenders, which I Had earlier been considering as itis getting near time for new tires anyway, and I was thinking of the Grand Bois Extra Leger but they don't come in a 35 in any case. 

Long story short, it might be a bit tighter for a 35, but still doable. Honestly haven't looked that closely yet to be sure, and if I can't, no big deal. 

Ty

Sent from my iThing

[Ely Rodriguez]

i'm considering re raking my fork or having a new fork made for my road bike, to slow down the steering and stablize it a little bit. its a little twitchy and i often feel a little nerve-racked after a long ride.
I'm thinking of re raking it or having a new fork made or buying an aftermarket fork with more rake.

[Ty's Gmail]

I just came back from my first real test with the re-raked fork. 

Went from my house in San Mateo up crystal springs road to Sawyer Camp trail to Skyline, then a nice speedy descent down Milbrae Ave., then back home along the Bay Trail. 25 miles round trip with a 2,000 ft. total elevation gain. 

Steering, stability, handling, etc., was all great with a semi-loaded handlebar bag. Very happy with how it came out. 

Oh, and my butt was super-happy after sitting on my new Rivett.  Didn't even wear cycling shorts. For me, MUCH better than my B17 ever was. No crotch pain!!!

Ty

Sent from my iThing

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