Saturday, September 30, 2017

Brompton M6R: DIY Lezyne Pump Mount and Tool Bag

One interesting thing about getting a Brompton is that most of them come with a hand pump included on the frame. As far as I know (correct me if I am wrong), only the E version (no mudguards) and titanium type do not include the pump.

The included pump is a Zefal branded hand pump, made specially for Brompton. It fits into a specially designed mounting area on the non-drive side rear triangle. The end with the handle has a hole, which goes onto a metal rod on the frame. The pump is then compressed slightly, and the pump head is then slotted into the holding frame at the other end. The spring inside the pump tends to extend the pump, keeping it tight within the frame.

Mounting of Zefal pump in the Brompton frame

This method of holding the pump is quite OK, however the pump itself is quite lousy. First, the pump head does not have a flexible hose, which means that during inflation of the tube, the pump has to be maintained at 90 degrees to the valve, to prevent damaging the valve. This makes efficient and ergonomic pumping quite impossible. Also, the construction and design is such that it is difficult to achieve a high inflation pressure with this pump. Brompton tires have a recommended inflation pressure of 100 PSI, which is impossible to achieve on this pump unless you have a lot of patience and strength.

As such, I have no confidence in using this pump to reliably fix a puncture if required. My preference would be to use a better pump such as a Topeak or Lezyne hand pump that has a flexible hose for ease of use. However, this also means that I will have to find an alternative way to bring the pump along, as it cannot be mounted like the Zefal pump.

I believe that most Brompton riders either use the stock Zefal pump, or bring a separate pump in a front carrier bag or in the jersey pocket. I would prefer to fix the pump to the bike itself if possible, so that I don't forget to bring it along.

The underside of the rear rack can be a useful place to store a separate hand pump, as shown in the picture below. However, you will need a way to mount it securely, so that the pump does not drop off or get lodged in the rear wheel. I imagine that it would be possible to secure it to the rear rack if you use velcro to tie the pump around the rear rack, or get creative with the use of rubber bands.

Simplest way to mount a pump to the rear rack would be to tie or velcro it at the area shown here.

After some tinkering and experimenting, I found that it may be possible to mount a pump to the frame, near the original Zefal pump mounting. What I would need would be a way to mount the pump bracket that is included with every Lezyne hand pump.

Objective is to mount the Lezyne pump in this manner, using the space left behind after removing the stock Zefal pump.

Looking through my box of spare clamps, I found a pair of seat stay clamps used for rear lights. I cannot remember which lights these clamps come from, but that does not matter. The Lezyne pump bracket usually mounts to the frame using the bottle cage bolts, but I will be using this pair of clamps instead.

Pair of clamps originally designed for mounting a rear light onto the seat stay. Rubber shim required to get the correct inner diameter.

After mounting the Lezyne pump bracket to the Brompton, using the pair of seat stay clamps.

Lezyne pump mounted onto the bike. Not as neat as the Zefal pump mounting, but this pump works better.

This is an S sized Lezyne Pressure Drive, which is shorter than the M sized pumps. From what I see, only S sized pumps will fit within the rear triangle, as the M sized pumps are too long. I like this DIY method of mounting a hand pump onto the Brompton, as it does not interfere with riding or folding, and allows me to bring along a better quality hand pump.

For puncture repair, there are three things that you need. The first is the hand pump as shown above. The next essential item is the spare tube or patch for the tube. I prefer to bring along a spare tube instead of relying on the patch, as it can be difficult to patch the tube while on the road. The faster and easier way is to swap in a fresh tube, and patch the punctured tube at home during your free time.

Lastly, you will also need a pair of tire levers to remove the tires from the rims. With these three items, you will be able to repair a puncture. Miss out any one of these items and you might as well not bring the other two.

How do we bring along the spare tube and tire levers? Once again, most riders who bring out these items either store it in the front carrier bag or in the saddle bag. I cannot mount a front bag on the front carrier block as I will be using the Bobike Mini child seat, which will interfere with a front carrier bag. As for using a saddle bag, I don't want to use it on the Brompton as it will prevent the seatpost from being lowered all the way. As the saddle bag sticks out from the back of the saddle, it will also make the folded size larger.

Therefore, I decided to do some DIY again and try to mount the spare tube and tire levers to the rear rack. The rear rack is very useful for mounting stuff at the sides, as the sides are unused and it will also not interfere with the folding.

The small bag that I found is a Schwalbe Race Saddle Bag, originally designed to mount under the saddle. I don't have a concrete idea on how to fix this saddle bag to the rear rack, I will just have to experiment with the actual bag after I get it.

Schwalbe Race Saddle Bag can fit a spare tube and tire levers, but not much more. I added a tire boot for good measure.

After testing out many different configurations, I finally settled on a mounting method that is secure, unobtrusive, and not too difficult to access.

The bag is mounted this way, so that it is wedged between two beams of the rear rack. The velcro straps will then wrap around the rear rack.

The top velcro strap is first wrapped around the top beam of the rear rack, followed by the wide grey velcro to secure everything in place.

It is very important to mount the bag securely. First, it needs to be secure so that it cannot drop off during the ride, even when riding over bumpy roads. Secondly and more importantly, for safety, it cannot dangle or lodge itself in the rear wheel, which will be very dangerous if you are riding and it jams the wheel. Same requirements needed for the DIY pump mount installed earlier.

View of the DIY pump mounting and bag, which carries the spare tube and tire levers.

With these puncture repair tools mounted to the Brompton, I will be able to repair any puncture on the roads, without needing to remember to bring out any spares or tools separately. Best of all, these DIY mountings do not make the folded package any larger, which is the main advantage of the Brompton.

Hopefully this can inspire some of you to do the same DIY mounting, which I feel is very useful and does not compromise the folding size or speed of the Brompton.

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