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[Brompton] Trunk bag to fit Brombacher rear rack?

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[Brompton] Trunk bag to fit Brombacher rear rack?

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Old 11-04-16, 07:13 AM
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Winfried
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[Brompton] Trunk bag to fit Brombacher rear rack?

Hello

I found this rear rack on eBay, which might actually be a copy of the Brombacher rack but it does the job just as well.

So I now need to find a rack top bag…
  • about 50cm/20" horizontally and 40cm/15" vertically to carry my camping gear (tent, matress, sleeping bag)
  • preferably waterproof, but I can always stick a drybag inside if it's not
  • Fast and easy to install/remove

Any idea where I could find a bag that would fit?

Thank you.
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Old 11-04-16, 08:32 AM
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tudorowen1
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Where is the company situated?
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Old 11-04-16, 09:05 AM
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The one selling the rack on Ebay? It says this when clicking on the account:

"Based in United Kingdom, chiman2288 has been an eBay member since Jun 26, 2005"

I assume it is just a copy from China, but shipping cost was more reasonable than the one charged by Brombacher.

Anyway, it looks like the 24 liter Ortlieb Rack-Pack could do the trick, although it'd have to be moved a bit to the back to provide enough heel clearance.
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Old 11-04-16, 09:39 AM
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Any where , any one will do, I have 2 that use velcro to attach top of any Rack.

Obviously you have to remove It, before you can use the rear rack as a your Brompton's Kickstand..

Velcro is easy to Use, for you , right?




You can always hold that Dry Bag down with a stretch Net, un hook it in a moments time.










'/,

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Old 11-04-16, 10:44 AM
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Topeak and Altura make a rack bag that is simply held on with a large sheet of velcro that is strapped to the rack..You can remove the bag in a second which would make it suitable to use when folding your Brompton..Both bags have expandable side panniers..
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Old 11-04-16, 10:52 AM
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Thanks much.

Wiggle | Altura Dryline Rack Pack | Rack Bags
Wiggle | Topeak RX Trunk Bag EX without Panniers | Rack Bags
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Old 11-04-16, 04:46 PM
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Originally Posted by Winfried View Post
I found this rear rack on eBay, which might actually be a copy of the Brombacher rack but it does the job just as well.
This rack lacks structural stability. Its stiffness relies on the ends of the bars that are flattened as they dive under the holding bolts. Not a good design.
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Old 11-04-16, 04:50 PM
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I'll report back in a few months.

Last edited by Winfried; 01-04-18 at 02:38 PM.
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Old 11-04-16, 06:23 PM
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After you fold the bike its weight rests on the rack and it needs to withstand being carted around. But sure, practice trumps theorizing. Looking forward to the report.
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Old 11-04-16, 07:55 PM
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Originally Posted by 2_i View Post
This rack lacks structural stability. Its stiffness relies on the ends of the bars that are flattened as they dive under the holding bolts. Not a good design.
I don't understand this. Are you saying that the flattened end of the bar are weak at the joints?
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Old 11-05-16, 04:13 AM
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I think the strength of the carrier depends on the grade of the aluminium...The whole weight of the bike may be put on the two rear supporting struts of the carrier when it is folded and put down on the ground quickly..On a Brompton carrier there are four supporting struts at the back..

An alternative to the Brombacher rack is the Nitto rack..http://www.perennialcycle.com/produc...idproduct=6413

Sadly it costs a fortune I think..$180 plus postage..

Last edited by tudorowen1; 11-05-16 at 05:59 AM.
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Old 11-05-16, 06:46 AM
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Thanks for the infos.

There's a third alternative: H&H's Titanium Rear Rack going for $125


https://dinokiddo.me/?portfolio=hh-t...a-for-brompton
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Old 11-05-16, 11:29 AM
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The Brombacher must be very good value at $45 and very light also..What looks good about the rack is it is likely to add a bit of strength to the front support struts of the forward rolling wheels..
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Old 11-05-16, 10:19 PM
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Originally Posted by Schwinnsta View Post
I don't understand this. Are you saying that the flattened end of the bar are weak at the joints?
What I am saying is that the design puts stress on those ends in lateral direction virtually ensuring failure in the course of time. If you look at the rack from the rear, you see a rectangle. A rectangle is floppy - think of a cardboard box with bottom and top removed. To prevent such box from flattening, you would need to stiffen the corners and stress would still concentrate by those stiffened corners so the stiffness would need to rely on stiffness of paper. Once you put just the bottom or top back, the shape is suddenly far more stable. Now the original Brompton rack does not put the bottom back, but uses triangulation with extra struts running at an angle to the outer ones:


This now removes floppiness of the shape. To deform the shape you need to compress or expand some struts. This design is superior to that of the cheap rack.
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Old 11-05-16, 11:38 PM
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Originally Posted by 2_i View Post
What I am saying is that the design puts stress on those ends in lateral direction virtually ensuring failure in the course of time. If you look at the rack from the rear, you see a rectangle. A rectangle is floppy - think of a cardboard box with bottom and top removed. To prevent such box from flattening, you would need to stiffen the corners and stress would still concentrate by those stiffened corners so the stiffness would need to rely on stiffness of paper. Once you put just the bottom or top back, the shape is suddenly far more stable. Now the original Brompton rack does not put the bottom back, but uses triangulation with extra struts running at an angle to the outer ones:


This now removes floppiness of the shape. To deform the shape you need to compress or expand some struts. This design is superior to that of the cheap rack.
Interesting, thanks for taking the time to explain that. How about the H&H Ti rack a couple posts up - is that rack inherently a better design/ more stable because it attaches to the brake bolt creating a sort of triangle, even though it has only 3 points of contact vs 4 points as in the OP?

Also, doesn't the fact that OP's rack attaches to the orange rear triangle of the bike act as some sort of "box top" to the rectangular rack?

Last edited by reppans; 11-05-16 at 11:42 PM.
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Old 11-06-16, 12:39 AM
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Originally Posted by reppans View Post
How about the H&H Ti rack a couple posts up - is that rack inherently a better design/ more stable because it attaches to the brake bolt creating a sort of triangle, even though it has only 3 points of contact vs 4 points as in the OP?
Shortening of the rack certainly relaxes somewhat the demands placed on the rack. Curving the outermost end of the rack spreads out stresses there. Still that one point attachment acts sort of as a pivot. In the original Brompton rack they inhibit rotation around that attachment point somewhat with a shaped washer and that triangulation acts against rotation too.

Originally Posted by reppans View Post
Also, doesn't the fact that OP's rack attaches to the orange rear triangle of the bike act as some sort of "box top" to the rectangular rack?
The two rather than one support points on top in the OP rack + bridge bars should certainly help, but they are very far from the outer end of the rack. I expect the outer end to be wobbly on a short time scale and getting shoved with the rack going out of shape on a long scale. However these are expectations - in due time we should find out from Winfried how things play out in practice.
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Old 11-06-16, 11:12 AM
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Originally Posted by Winfried View Post
The one selling the rack on Ebay? It says this when clicking on the account:

"Based in United Kingdom, chiman2288 has been an eBay member since Jun 26, 2005"

I assume it is just a copy from China, but shipping cost was more reasonable than the one charged by Brombacher.

Anyway, it looks like the 24 liter Ortlieb Rack-Pack could do the trick, although it'd have to be moved a bit to the back to provide enough heel clearance.
You just linked the perfect commuter bag for me,...thank you. The 31L might be a bit large, but the 24L would be perfect.
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Old 11-06-16, 11:16 AM
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My karma went up :-p
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Old 01-04-18, 02:38 PM
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Originally Posted by Winfried View Post
I'll report back in a few months.
I've been using that $50 aluminum rack bought on eBay for almost two years, and it's fine. I've done several trips with it, and carried a bit of groceries:


(yes, I might get a Burley Travoy or a Carry Freedom Y Large trailer).

Lighter than the original from Brompton, and 3-4x cheaper than alternatives in titanium.

Last edited by Winfried; 05-02-18 at 05:01 AM.
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