6 spd Brompton riders - ever changed your rear cogs?

I haven’t but I’m curious! It feels like the rear sprockets give halfway gears in between the hub gears. It is rather high geared for the hills of Brighton, might as well be a singlespeed!

I know what you mean...the 2 speed 'derailleur' doesn't really make a big change to the ratio. (16:13).  Only a bit.  It's like an 'overdrive' in a Triumph Dolomite.

I ended up swapping the front chain ring (to a 44 from 50, I think) to get a lower easier gear for some steep-ish hills when heading home on it. It loses a bit off the top end but that's not a big issue anyway - just pedal faster.!

I find you can use the derailleur to make the steps in the 3-speed smaller. It does make shifting a more complicated affair but if you ride it often enough the muscle memory takes care of it. If I rode anywhere hillier I'd definitely get a smaller front ring.

So smaller front ring vs bigger rear cog seems the consensus?

Years ago I bought different rear cogs with the intention of doing this, but never did.

Got the idea from an article in AtoB magazine, I think.

Don’t suppose you want to sell them do you?

I fitted a smaller chainring (44t) to my 6speed. Loads better range for all sorts of riding especially if you are used to higher cadence. I had a two speed prior and again went down a chainring a bit.

some I for on all the various ratios here:

https://www.andythousand.com/brompton-gear-ratios/ 44t on 6 speed is the Brompton -12% option.

would like to test their new 4 speed derailleur.

And with 6speed you just need to get used to double shifting to get even shifts.

Don’t suppose you want to sell them do you?

If I can find them you can have them,

Thanks Crispin 🤩

Late to the party on a 4-month old thread but this might help:

I found three 11s cogs would replace the two so used 13 15 17 with a suntour six speed shifter from the early 80s. For touring I used a 39 ring. It was still laborious up hills mainly due to the inefficiency of the hub gear (only 84.6% efficient in bottom gear apparently). Riding through a flood filled the hub with water on one tour which made it even less efficient.

Then I saw a 7-speed derailleur Brompton on Youtube. I bought all the bits from Ali: 11s spaced 7s cassette, derailleur, shifter, pair of wheels with a 110mm rear hub and specific narrow cassette body, about 300e delivered IIRC. It works perfectly and saved about a kilo which is a bonus when carrying it around. 11-28 with a 52t chainring at present, I may fit a smaller ring for touring. Why Brompton don't do it I have no idea, it's efficient, light, no double shift faff, easier to repair a puncture. Their latest range includes a 4 speed, I'd be interested to know how wide the cassette body is and if it's compatible with the aftermarket 7s systems.

This is a bike thread I can actually contribute to!<br /><br />

I haven't ridden it in a while, but my Brompton was converted from the 2- speed system to the 6-speed, because a friend gave me a wheel and some other parts. So I had the rear wheel swapped over, the new shifters installed and another small part that I can't remember. Changing gears is a bit fiddly, because you have to change the left shifter, then the right, then the left etc to go through all the gears. It's been so long that I've forgotten the combination, sorry. It's not as simple as left 1, right 1, 2, 3, left 2, right 1, 2, 3. You have to 'cross over'. It's a pain in the arse tbh. I've only got the Brompton because I got it very cheap off a family member who quickly discovered that riding a bike actually involves more effort than driving a car. So lazy. They've recently been diagnosed with high blood pressure,  so perhaps they should have stuck with it. <br /><br />I also had it converted from a larger front ring to a smaller one. Apparently this makes a difference and is easier to pedal up hills. I do know that it all costs an awful lot of money, so I'll probably sell it. It's kind of useful sometimes, to throw in the back of a cab or jump on the train etc. A dilemma. I much prefer my regular bike though, as it's a lot easier to ride. But then you can't throw it in a cab or come home on the train. What to do?

I'm a year into riding a 6 speed Brompton, love it. Took my thumbs quite a while to get the muscle memory for the natural sequence changing gears but now its smooth. Stock ratios are perfect for my routes, Surrey and central London. Only trouble is when I hop back on a mtb at the weekend my thumbs have forgotten which way is up and down the gears, and my brain-arm calibration is messed up for steering

I bought a T6 new in 2003 and soon after converted the fork to take a set of V brakes as well as bolting on an inner granny ring . I did buy a special custom made derailleur to fit but never used it as I only used the granny ring very occasionally and simply did a manual shift with the foot then at the top of a long climb put it back on the big outer ring with a stick . Loads of folk now fit a double chainset or add on a granny as well as numerous other mods ..just join brompton hacks on FB but be warned ..there are numerous brompton obsessives on there ..many who  obviously know very little about bikes but offer advice on everything nethertheless  as well as many Asian owners who spend 1000's on bling parts There are also some genuinely knowledgeable enthusiasts also .. "Will Kettle" comes to mind ..He has a blog about his various mainly practical modifications including a campag double chainset + all the info re his projects . Worth a look if interested : http://mybikesite.org/

prior to my current six speed, and for Lejog (wow back in 2011 - how time flies) fitted this Stronglight double for a kick chain down and lift back on with finger, as did my riding buddy - here him fixing one of only two punctures the whole trip

worked well.