Mid-Trail for Front Loads?

[Mitchell Gass]

I reread with great interest the article "Front End Geometry for
Different Speeds, Loads and Tire Sizes" in VBQ Vol.3 No. 3 (Spring
2005). I have an older mountain bike frame - a late 90's Bridgestone
MB-1 - and I'm interested in having a fork built for it that could
make it suitable for loaded touring.

The bike described in Figure 6 of the VBQ article, the Alex Singer
Camping No. 2711, looks like it might be a good starting place for
the design of a new fork. The article says that the bike is "Stable,
can be ridden no hands with 80 lbs. load at moderate or high speeds.
Corners great." The head angle is close to that of the Bridgestone
(71.5 degrees vs. 72 for the Bridgestone), and it has a longer stem
like the one I expect to use.

So, if I have a fork built with trail similar to that of the Alex
Singer (49 mm), what can I expect? I'd use tires that are somewhat
larger, most likely 44 or 47 mm wide (26 X 1.75), and a Bruce Gordon
low-rider front rack when loading the bike, with large panniers in
front carrying the majority of the weight.

- How is it likely to ride without a load? (Jan, if you did the test
ride of the Alex Singer for the article, was this something you tried?)

- Would the bike still be suitable for riding off pavement, with some
occasional loose surfaces? The ideal would be for the bike to work
well loaded when on pavement, while still being a credible mountain
bike when unloaded. The stock fork (with rake listed in the
Bridgestone catalog as 66.3 mm) makes for a rather twitchy ride,
particularly on slow steep climbs, and I'm hoping that the somewhat
lower trail will be an improvement.

Thanks for any suggestions!

Mitchell Gass
Berkeley CA USA

[Mitchell Gass]

Oops, 66.3 mm is the trail listed for the stock MB-1 fork, not the rake.

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[Jimmy Livengood]

Hi Mitchell, 

I'm about to embark on a similar experiment. I've got an old Rockhopper built as a townie with front rack, and I'm going to move everything directly over to an MB-2 of the same size. Hopefully the MB's steeper head tube angle will help with the front load. We'll see.

Also, I have a Miyata Valley Runner that has a custom 63mm offset fork for it. Right now it's a bare fork, and needs canti studs and rack bosses added to complete the bike. When it's done it in theory will be very much like what you're describing. 

I wish I had more to tell you, but if you have some patience I will report back when things are finished up and I've ridden them a bit. Right now the Rockhopper/MB-2 has 26x2.25 tires on it(Schwalbe SuperMoto -they are really very nice), and I'll probably use those same on the Miyata. I may downsize a bit to 26x2.0 Schwalbe Kojaks, which some friends have and speak highly of. 

I have a friend with a lowtrail rawland rSogn, and he's ridden if off road (genuine singletrack MTB trails) with knobbies and also with Hetres on many gravel roads here in the PNW. No issues that I can see. He does generally have at least s small toolbag at the front, adn the platform rack he has itself adds some weight, so I don't know if that's a direct comparison to your question of fully unloaded riding. 

Cheers,

Jimmy

Seattle 

[Mitchell Gass]

Jimmy,

Thanks for the reply! As it happens, I've already worked out the
details with the framebuilder, and I expect to get the fork in the
next few days. It will have 40 mm of trail with the 42-559 tires I
plan to use. Thanks to everyone who sent suggestions.

Mitchell

[Tom Perkins]

Hi All,

 

I just wanted to add that I am also interested in this discussion of trail and front loads. I have been collecting for some time now steel frame bikes that riders are throwing away in favor of carbon and aluminum. I have quit a collection now of steel frames and forks. Recently, I have been brazing on canti studs, rack bosses and made a front rack out of 1/2 inch conduit. For the design of the cargo rack I use the photos in vol. 10 No. 4, “Working bikes in Florence” (summer of 2012).  Unfortunately, my BQ collection only goes back to 2007 and I do not have “Front End Geometry for Different Speeds, Loads and Tire Sizes" in VBQ Vol.3 No. 3 (Spring 2005).

 

Tom Perking

Burlington Wisconsin

[Mitchell Gass]

At 12:54 PM 3/12/2013, Tom Perkins wrote:
>I just wanted to add that I am also interested in this discussion of
>trail and front loads. I have been collecting for some time now
>steel frame bikes that riders are throwing away in favor of carbon
>and aluminum. I have quit a collection now of steel frames and
>forks. Recently, I have been brazing on canti studs, rack bosses and
>made a front rack out of 1/2 inch conduit. For the design of the
>cargo rack I use the photos in vol. 10 No. 4, "Working bikes in
>Florence" (summer of 2012). Unfortunately, my BQ collection only
>goes back to 2007 and I do not have "Front End Geometry for
>Different Speeds, Loads and Tire Sizes" in VBQ Vol.3 No. 3 (Spring 2005).

Hi Tom,

Do you have the Spring 2007 BQ? The article "Optimizing Bicycles for
Carrying Heavy Loads" in Volume 5, Number 3 (Spring 2007) has a lot
of information that could be helpful.

Best,

Mitchell Gass
Berkeley CA

[Jan Heine]

Just a quick note that all back issues are available. You can mix-and-match volumes - $ 32 will buy you any four issues. As an aside, selling back issues helps us amortize the high cost of the research. (Ever wondered why no other magazine actually does any research?)

When you look for information on a particular topic, you can start here:

http://www.bikequarterly.com/BQ_subject_index.html

Jan Heine
Editor
Bicycle Quarterly
www.bikequarterly.com

-----Original Message-----
>From: Mitchell Gass <mitch...@gassworks.com>
>Sent: Mar 12, 2013 1:13 PM
>To: Tom Perkins <bassw...@yahoo.com>, Jimmy Livengood <jimmyli...@hotmail.com>, Bicycle Quarterly Readers Review <bq...@googlegroups.com>
>Subject: Re: Mid-Trail for Front Loads?
>