It was time for upgrading the luggage capacity of my Brompton. For its weight and grandpa-look I do not like Brompton’s rear rack. By now I was cycling with a backpack every day. In fact, even wearing biking clothes and using a backpack with a highly sophisticated venting system I dreamed about a more comfortable way of cycling. Being committed to Ortlieb bags the plan was to adapt a standard Brompton front carrier frame to hold an Ortlieb bag. The advantage: As most of you I do already have an Ortlieb bag.
An here we go:
1) You need
- 3mm inbus
- (knife)
- rule
- pen
- saw
- 3.5 & 4mm drill and drill machine
- 4x4mm rivets and rivet gun
2) You do…
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| 1) … use this Brompton standard frame for the front carrier, which is way too wide… | 2) … and this standard Ortlieb backpack, volume 20l, having a width of 32cm. |
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| 3) By pressing down the adapter from top… | 4) … you get the adapter off and the clamp should fit the tubes of the frame. Now, mount the clamps upside-down using the inbus. |
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| 5) Mounting the bag to the frame shows why – the Ortlieb would otherwise be too high. Don’t worry about the clamps, the weight of the bag is carried by the plastic foot of the frame. | 6) Screw off the bottom holder and place the metal piece underneath the bottom rails. |
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| 7) This proves the concept but also that there is some potential… Let’s narrow the frame. | 8) Drill off the two bottom and top rivets with the 3.5mm drill (4mm would do as well). |
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| 9) Draw out the frame tubes. | 10) Saw about 6cm off each end of the tubes. (Hint: you can shorten the lower end of the tubes by another 1cm to realize a V-shape fitting more nicely the Ortlieb bag.) |
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| 11) Assemble the tubes back into the plastic part. | 12) Drill the holes for the new rivets into the tubes using the 4mm drill. |
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| 13) Press in the 4mm rivets… | 14) … and clench it using the rivet gun. |
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| 15) In case you have a S-type Brompton saw off the handle. Otherwise the brake cables will harden steering | 16) Nice side effect: you save 54g… |
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| 17) … and get a total weight of 330g. | 18) Mount the bag to the frame, tighten the bottom clamp and that’s it. Btw: The Ortlieb bag might rattle. I suggest to use some tape to perfectly fit the clamps to the tubes. |
Have fun tuning your Brompton!
Cheers, denlinne