Today, we have some great news for all you Brompton fanatics out there. In this featured video by Oliver Wilhelm, you will learn how to fix Brompton gear shifter problems that can occur in 2 and 6-speed Brompton models, 2017 and newer.
As many of you already know, we’re huge Brompton fans ourselves. Ever since we bought a Brompton 2-speed from NYCEWheels over 6 years ago, this high quality, hand brazed beauty has been everywhere.
We’ve used this folding bicycle to commute, ride public transportation, and even grocery shopping.
The reason why we love this tiny folding bike is because of it’s high quality build. A neat and compact fold that can’t be matched. The ability to update it no matter how old of a model it is. And the large variety of accessories such as the Brompton cover bag, Brompton carry handle, along with the Brompton sport bag.
What’s great about the Brompton folding bike is that it’s always improving. Ever since Andrew Ritchie started designing this folding bike in his flat overlooking the Brompton Oratory in South Kensington, London, the frame along with all the components have been improving, such as the gear shifters introduced in 2017.
But what makes this folding bike so special is that no matter how old the model is, every updated component will fit on it. The Brompton definitely isn’t a disposable product! That’s why many people own them for many years.
Unfortunately, there’s been a problem with the newly designed gear shifters, that Brompton is fully aware of, and I’m positive they will fix.
Here’s what Oliver Wilhelm has to say about how to fix Brompton gear shifter problems
FIXED: Brompton Gear Shifter Problems 2/6-speed 2017 & newer.
My wife and I are traveling the world (@smartveganlife) and we recently switched to new H6R Brompton bicycles (2019).
After only two weeks in the humid heat of Bali, shifting problems started to occur on both bikes simultaneously. The derailleur stopped switching completely and the hub shifter got stuck when switching from 1 to 2.
It took us quite some time until we discovered the problem. It turned out that the cause of this problem is a combination of temperature and humidity.
Somehow the plastic material of the Brompton gear shifters expands, which leads to higher friction within the gear shifter housing.
The “simple” sanding of certain parts within the gear shifter housing reduces the friction, and the derailleur and hub switching operation works fine again.
In this video, I document the procedure on how to fix the Brompton gear shifters and get them working again! I hope this will save you some precious time.
P.S: Brompton is aware of the problem
Watch the video for complete details
- Intro – 0:00
- Which Brompton are effected? – 0:10
- Description of the problem – 0:22
- Experiencing the problem – 0:34
- Origin of the problem – 2:12
- Disassembly (derailleur gear shifter) – 3:20
- Fixing the problem (derailleur gear shifter) – 5:14
- Reassembly (derailleur gear shifter) – 7:08
- Disassembly (hug gear shifter) – 10:15
- Fixing the problem – (hub gear shifter) – 10:29
- Reassembling (hub gear shifter) – 10:56
- Testing the shifting mechanism – 13:03
- Brompton CEO confirms the problem – 13:32
How to fix Brompton gear shifter problems
DIAGNOSE THE PROBLEM:
Detach the derailleur shifting cable from the dogleg spring, and manually pull/tension the shifting cable while shifting from (+ low gear) to (- high gear).
Disassemble the shifter (carefully). The thumb shifter is connected to the main ratchet (moving mechanism) by a bolt. You’ll need to remove the ratchet (which is a single piece that includes the shifter cable threadthrough) and find that the ratchet may be really tight/stuck to the shifter base.
For whatever reason (temperature? humidity?) the ratchet part will likely be tightly bound to the shifter base, leading to high friction and preventing downshifting. You will understand when you see that thumb pressure is needed to shift from (+) to (-), while a white locking ratchet prevents passive spring tension from downshifting to (+) unless your thumb movement unlocks the ratchet.
The downshifting is mediated by passive spring tension from the dogleg, and overly tight/shift cable puller may be the cause for poor downshifting performance, as the spring tension is insufficient to fully pull the ratchet back to (+) position.
Since all the working parts are plastic, you’ll be able to gently sand the ratchet mechanism after removing it from the shifter base. A quick circumferential sanding with mod-grit (eg. 400) sandpaper will increase the inner diameter/circumference of the moving ratchet.
DON’T OVER-DO THIS:
Just a few passes with sandpaper wrapped around your finger will do, you won’t be able to visually see any difference. Clean both parts (shifter base and ratchet) and check the fit. Both pieces should still interface well but you will notice there will be much less twisting resistance. Sand down to your preferred level of smoothness.
I would say go slowly, check multiple times, as you can always sand more. But if you go too far, it’s much harder to add thickness back to the plastic part. Once sanded, just clean and relabel before re-assembly.
Might also want to lube the shifter cables as thread into the cable housing just to minimize friction in the entire system. Re-assemble everything and test.
Thank you for watching
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