pivoting rack, for rear suspension?

[[email protected]]

I'd like a normal rear bike-rack suitable for carrying a decent load
(those seatpost-only racks don't look like they'd hold my commuting
load of spare clothes etc). To cope with changing angles due to rear
suspension (I have a KHS soft-tail mtb, short travel) it would pivot
at the three main points: seatpost attachment, chainstay attachment
point, and rack-to-top-of-support-arm attachment.

Are these made, or if not why not, and then- any tips for how to make
one, if its a good idea?

thanks,
Charlie

 

[Ron Hardin]

[email protected] wrote:
>
> I'd like a normal rear bike-rack suitable for carrying a decent load
> (those seatpost-only racks don't look like they'd hold my commuting
> load of spare clothes etc). To cope with changing angles due to rear
> suspension (I have a KHS soft-tail mtb, short travel) it would pivot
> at the three main points: seatpost attachment, chainstay attachment
> point, and rack-to-top-of-support-arm attachment.
>
> Are these made, or if not why not, and then- any tips for how to make
> one, if its a good idea?
>
> thanks,
> Charlie

I buy only hardtail bikes for that reason. Look into the Nashbar
wicker basket, for up to about 15-20 pounds, on the front. They are
extremely handy, cause no air drag, and block cold winds from the
vital crotchal area in the winter. $25-40 depending on sale.

They're handlebar mounted with no other supports, and so don't care
about suspension. I put a tiny strip of wood under the stem part of
the mount, to make it ride a bit higher under load (this will make
sense when you mount one).
--
Ron Hardin
[email protected]

On the internet, nobody knows you're a jerk.

 

[tiborg]

I've seen seatpost only racks rated for 9-10kg. I load mine (Topeak
MTX) with a full set of clothes, minitool, patch kit, first aid kit,
spare tubes, hand pump, 7200mAh battery and lunch and still have
weight to spare.

 

[Kinky Cowboy]

On 25 Mar 2007 05:12:16 -0700, [email protected] wrote:

>I'd like a normal rear bike-rack suitable for carrying a decent load
>(those seatpost-only racks don't look like they'd hold my commuting
>load of spare clothes etc). To cope with changing angles due to rear
>suspension (I have a KHS soft-tail mtb, short travel) it would pivot
>at the three main points: seatpost attachment, chainstay attachment
>point, and rack-to-top-of-support-arm attachment.
>
>Are these made, or if not why not, and then- any tips for how to make
>one, if its a good idea?
>

In general, not a good idea; you're making your luggage part of the
unsprung mass, not to mention the complexity and expense of making
different racks for every suspension configuration. A cantilever off
the main frame is the way to go, see Moulton.

If your bike looks like this
http://www.k5.dion.ne.jp/~u-roak/LOVELOG_IMG/TS280003.JPG a normal
rack rigidly mounted to the rear triangle will work just fine; your
suspension is mostly there for decorative effect anyway, so spoiling
it by tripling the unsprung mass won't be a great loss.

Given that a seatpost is designed to take about 100kg, it should be
possible to reinforce a seatpost rack for a decent load (unless you're
already a Clydesdale class rider); the weakness is the weld joining
the beam to the post clamp, adding some struts or tie rods 6 inches
down or up the post will make a huge reduction to the stress on the
weld

You can also put a lot in an old fashioned saddle bag; it was
traditional in the old days, if somebody was tearing it up too much on
the Sunday club run, to put a couple of bricks in his saddle bag at
the tea stop to take the edge off his enthusiasm

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

 

[daveornee]

I'd like a normal rear bike-rack suitable for carrying a decent load
(those seatpost-only racks don't look like they'd hold my commuting
load of spare clothes etc). To cope with changing angles due to rear
suspension (I have a KHS soft-tail mtb, short travel) it would pivot
at the three main points: seatpost attachment, chainstay attachment
point, and rack-to-top-of-support-arm attachment.

Are these made, or if not why not, and then- any tips for how to make
one, if its a good idea?

thanks,
Charlie

http://www.oldmanmountain.com/Front_Rack.htm
Front rack that can "easily" attach to your suspension fork.
Take a look at the <PHOTO GALLERY> and scroll down to see what it looks like.
Rear racks for soft tails are too complex and difficult to get adequate bracing while giving secure attachment points. Since there are many different soft tail designs it is nearly impossible for a rack to be made that would work on more than one design. It could be done, but the costs would make it out of the question for marketability.
You can call Old Man Mountain and ask them what they can do for you. They do custom work.
I have no connection with them other than buying a few of their products. They are well made and on the higher end of the price spectrum.

 

[Mark Hickey]

[email protected] wrote:

>I'd like a normal rear bike-rack suitable for carrying a decent load
>(those seatpost-only racks don't look like they'd hold my commuting
>load of spare clothes etc). To cope with changing angles due to rear
>suspension (I have a KHS soft-tail mtb, short travel) it would pivot
>at the three main points: seatpost attachment, chainstay attachment
>point, and rack-to-top-of-support-arm attachment.
>
>Are these made, or if not why not, and then- any tips for how to make
>one, if its a good idea?

That's a lot of effort and complexity (and potential failure points)
for a rack. Then there's the issue of your baggage flopping around,
changing its relative position, affecting the center of gravity - not
sure what issues you'd encounter with an "articulated" rack, but I'm
sure it would be "interesting".

The Delta seat post rack I used for years was rated at 25 pounds
(11.3kg), which is more than 99.5% of commuters use (OK, I made up the
statistic, but it's probably not TOO far off). ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

 

[JeffWills]

On Mar 25, 5:32 am, daveornee <daveornee.2o0...@no-
mx.forums.cyclingforums.com> wrote:
>
> http://www.oldmanmountain.com/Front_Rack.htm
<snippedy>
> Rear racks for soft tails are too complex and difficult to get adequate
> bracing while giving secure attachment points. Since there are many
> different soft tail designs it is nearly impossible for a rack to be
> made that would work on more than one design. It could be done, but
> the costs would make it out of the question for marketability.
> You can call Old Man Mountain and ask them what they can do for you.
> They do custom work.
<snippedy>

Take a look at
http://www.oldmanmountain.com/rear_rack_page.htm
They're *designed* to work on rear suspension bikes, even those
without dropout eyelets. It might be a little tougher if the KHS in
question lacks rim brake mounts, but a couple "P" clips should solve
that.

Jeff

 

[Michael Press]

In article
<[email protected]>,
[email protected] wrote:

> I'd like a normal rear bike-rack suitable for carrying a decent load
> (those seatpost-only racks don't look like they'd hold my commuting
> load of spare clothes etc). To cope with changing angles due to rear
> suspension (I have a KHS soft-tail mtb, short travel) it would pivot
> at the three main points: seatpost attachment, chainstay attachment
> point, and rack-to-top-of-support-arm attachment.
>
> Are these made, or if not why not, and then- any tips for how to make
> one, if its a good idea?

I do not understand all the pivoting requirements.
The Blackburn Expedition is. 600 grams and rock solid.
I have been running one on a utility bike for 15 years.
<http://www.touringcyclist.com/gear/model_7587.html>
--
Michael Press

 

[[email protected]]

On Mar 25, 11:19 pm, Kinky Cowboy <[email protected]> wrote:
> On 25 Mar 2007 05:12:16 -0700, [email protected] wrote:
....
> If your bike looks like this http://www.k5.dion.ne.jp/~u-roak/LOVELOG_IMG/TS280003.JPGa normal
> rack rigidly mounted to the rear triangle will work just fine;

Yep that's what my sus is like, and that rack hasn't interfered at all
-- I still get the almost-inch of travel when I bounce hard down on
it. Though without eyelets at the frame and a nutted wheel, I had to
rig up a connection. I cut two 1.5" long thin steel tubes, thick as
my pinkie finger. Flattened half of it, making a hole for the axle.
The other end i left tubular, and put a little bolt through that,
which becomes the axle for the rack to mount on (and rotate around,
and needed a plastic sleeve to stop it rattling) The top of that is
riveted to articulate anyway, and the seatpost-attachment still seems
happy to move however it needs to (and the seatpost QR clamp is still
tight enough to hold the seatpost up.)

>your suspension is mostly there for decorative effect anyway, so spoiling
> it by tripling the unsprung mass won't be a great loss.

I only commute, so I'm thinking/hoping that even the small-travel
suspension does actually help smooth out my ride, by soaking up little
pavement edges & bumps. Plus I converted the bike into a Cruzbike
recumbent, so I can't unweight the bike when a bump approaches.

What does 'tripling the unsprung mass' mean, and how does it spoil the
suspension?

thanks,
Charlie

ps. those Oldman racks look great, but too expensive for me,
especially as this el-cheapo one seems to be working. I have a wire
box on it that I through a small rectangular bag into (size of two
shoeboxes) and its very convenient for work gear.

pps. Michael Press, the pivoting requirement was to let the bike's
rear suspension keep working. If I made it fully rigid, then it would
be trying to stop the rear end compressing.