# Modding a Brompton B75



## DBrown67 (26 Nov 2019)

I've been hankering after a Brompton for a while now. My daily commuter is a Cube mtb that I put an electric kit on. I can go anywhere on it and won't be getting rid of it but it is a heavy lump to take in the car. So for summer use when I go away for weekends I want a folder.

Saw the B75 this summer and loved the colour. Having looked into it I see it as a blank canvas to mod to what you want. But it already comes with stuff I'd want anyway like extended seat post and 44T chainring for lower gearing. Mud guards are a must add.

One thing I disliked about an M that I test rode was the bars seem quote narrow which would be the same for any model. Found it a bit twitchy. I suppose I'd get used to it but I don't see why I couldn't swap out the M-bar and fit a mid riser with around 80mm rise. It should in theory put the bar to the height of an S and the wider bar should still fold OK. The cables will become slacker by lowering the height but some would be taken up if the brakes etc. move further out a touch on the extended bar.

I was in Halfords at the weekend and sat on a Dahon Uno. It just looked so simplistic (though single speed no good for me), the bar height felt perfect and was wider than the Brompton. That measured 1000mm from ground to bar so not too far from that should be fine.

If I do take the plunge it will deffo be a B75. Anything else is just too expensive and I can't even get that colour unless I buy a B75. So I see this as the best option for me if I'm doing a few mods.

Just wondered what others might have done with the bar on a pre-2017 3 speed (as that is effectively what the B75 is)


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## Cycleops (26 Nov 2019)

@chriscross1966 is our resident Brompton modder here.


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## 12boy (26 Nov 2019)

I have tried a number of things on my S of which some were good and some not:
Bar ends for a break from the normal flat bar hand position. Cut short didn't affect the fold.
Ergon cork grips which were nice but especially with bar ends use a lot of space.
Ergon rubber grips with tiny bar ends. Those bar ends were too small to help me.
Velo Orange Porteur bars as 480 mm width. Great hand position but their narrowness seemed too twitchy for safety.
Velo Orange Milan bars which rotated in the clamp but otherwise comfy.
Salsa moustache bars flipped down, currently in place and used with DuraComp drop bar brakes. Also used with a QR on the stem clamp so folding is possible. Those bars will accept Sturmey bar end shifters if that is your pleasure. 
Probably more than you want to know but my 2 cents worth.


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## Geedubbayoo (26 Nov 2019)

DBrown67 said:


> One thing I disliked about an M that I test rode was the bars seem quote narrow which would be the same for any model. Found it a bit twitchy.



Did you have a front bag with some weight in it attached to the Brompton during your test ride? I did not the first time I tried one and walked away unimpressed. It did feel twitchy, unlike the “regular” bikes I was used to riding with larger wheels. But a few weeks later, after trying a few other folders, I went back and this time the clerk put a weighted bag in the front. It was a much better experience. I could be wrong but the problem might not be the width of the bars.

And yes, after buying one I have since become accustomed to riding it in its “twitchier” configuration (no weight in front). While I can tell a difference it’s not a negative experience at all, at least for me.

Greg W


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## Kell (27 Nov 2019)

First off, Bromptons are very twitchy - even more so coming from an MTB.

I remember trying a road bike for the first time in years after being on an MTB and that felt twitchy. Now, going back to that after being on the Brompton it feels so stable. Going back on the MTB, it feels like it's never going to turn at all.

I modded mine with a set of Ritchey low rise bars. Although I did end up sawing (badly) the ends off to make them a little narrower.

I’ve just ordered another set as mine are now a few years old, and I’m replacing all the alu parts as my cranks recently snapped.

You’re welcome to have the old bars to try out if you’re anywhere near High Wycombe. I’d offer to post them to you, but suspect the cost of postage would make it prohibitive and you may as well just order a new set.

I ordered an H type originally and fitted these because the S type was just too low and the M type felt too high.

Luckily my rough calculations proved correct and the bars ended up somewhere between M and S and the added height of the fold in the H stem meant they still have ground clearance.

I’ll add some pics to this post when I get to work.


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## Kell (27 Nov 2019)

Pics:

My bike as I ordered it:







Immediately after adding the bars...











How it folds:






This was the diagram I used to work out relative bar heights, but I don't think it applies to the new bikes as they tried to standardise the stems.






As I think you should be able to see from the diagram above, the length of the stem differs (or differed) when I ordered my bike. The M-Type and P-type are different parts, but look to be a similar length. Whereas the S-Type and H-Type are also different parts and also look to be of a similar length. So putting 80mm riser bars on a M-type would make it about the same height, if not lower, than an S-type.

If you assume the clamp of the H-type and S-type are the same height, then my 30mm riser bars should give a grip height of around 954. I did measure the height of mine at one point for someone else, but didn't record the figure.

Works for me. The only thing that is a slight issue, is that when you turn the steering all the way to the right, it does pull on the front brake cable and activate the front brake, but this is only when maneuvering the bike rather than when cycling. 

I've often wondered if you could run the brake cable the other side of the main tube to help prevent this, but have not investigated it yet.

YMMV.


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## Kell (28 Nov 2019)

80mm riser bars are available from Joseph Kuosac too.

https://www.sjscycles.co.uk/handleb...bar-for-bromptons-mid-rise-254mm-clamp-black/


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## Tenkaykev (28 Nov 2019)

Kell said:


> 80mm riser bars are available from Joseph Kuosac too.
> 
> https://www.sjscycles.co.uk/handleb...bar-for-bromptons-mid-rise-254mm-clamp-black/



I purchased those for my C3 Kell. I have a 2015 Orange Black "M" as my everyday Brompton, and my C3 has been "blinged" up a bit.
I find the "M" more suited to my bimbling about, and the riding position more comfortable and so had planned to fit the Joseph Kuosac bars to the C3 to bring it up to "M" handlebar height but I just can't bring myself to do it yet, I think I like the S bar aesthetic on the C3.

I suppose that there is nothing to stop me fitting the bars and new "M" brake and gear shifter cables to give it a go, I could then just swap them back if it doesn't work for me.

Incidentally I fitted the Joseph Kuosac Brompton "M" bars to my Orange / Black bike and cut the bars to take a 130mm Ergon grip. It folds ( just about ) without the handlebar hitting the ground but it is very close.


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## Kell (28 Nov 2019)

Unless I’ve misunderstood (probably) why would the JK bars be nearer to the ground than standard M bars?

is it the width rather than the height?


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## 12boy (28 Nov 2019)

I installed a v-brake noodle on the last part of cabling to the front and run my cables as I wish, having dispensed with the piece that spits the front cable and has a loop to gather the rear. Someday I'll put a top pull side pull brake and make it even simpler.


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## Tenkaykev (29 Nov 2019)

Kell said:


> Unless I’ve misunderstood (probably) why would the JK bars be nearer to the ground than standard M bars?
> 
> is it the width rather than the height?



The JK bars are the same height as my ( 2015) M bars but wider, you can fit standard 130mm grips. I used a plumbers pipe cutter to trim them down. They have mm markings either side of the bars to assist measurement.
You could have them assymetric and leave a bit extra for your Garmin / light / mirror on the right hand side if you wished.


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## DBrown67 (29 Nov 2019)

Thanks for the advice guys... and specially to Kell for the offer of the bar. I'm in Leeds but I think a flat bar on a B75 would be too low at 933mm high overall. Remember the B75 uses the older (shorter) stem and older bar (150mm rise) even though the height is still the same as current M models at 1083mm. But an 80mm riser will at least get it to 1013mm which is between the S and M and very close to that Dahon Uno I sat on, while at the same time allowing a slightly wider bar not affecting the fold.

This is all on paper of course. Provided the measurements on Brompton and SJS websites are accurate I don't see why it wouldn't work out.

I'd be getting it from Halfords as well for the 10% British Cycling discount. Cycle Republic exempts Bromptons (you only see this in the small print) and Evans is 10% off accessories only.


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## Kell (29 Nov 2019)

Not sure where you got the 1083 from.

The current M type height (according to Brompton) is 1015. In fact, most of the heights of the new models are within a mm or two of the pic I posted above. 

I just found this online that gives the heights of the current bikes.






According to the link for the JK 80mm handlebars, it says that fitted to the older S-type stem would give a bar height which is the *same *as the current M type. This can't be quite right, as in both the new and older versions of the bike the difference between S and M is 90 mm.

The Ritchey bars I have have a low rise of 30mm putting them at about 955.

Of course, the height of the bars is only relevant if the seat height on the Dahon is the same - which would depend on BB height and crank length.

Good luck.


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## DBrown67 (29 Nov 2019)

Yeah that was my bad. It's not 1083mm... it's 1015mm as you pointed out. But fitting the 80mm riser still puts it at 945mm on the older stem which is 20mm over the current S model. Fitting the later Brompton bar (120mm rise) does not widen them, so pointless really.

EDIT: Just found this at 100mm rise x 600mm wide and someone in the review section confirms they are great for the B75 with no cutting required. https://www.sjscycles.co.uk/handleb...ar-for-bromptons-mid-rise-254mm-clamp-silver/


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## Kell (30 Nov 2019)

They sound perfect.

Hope it works out

Out of interest, which stem is on the B75. I couldn’t find out online, but had assumed it was the old S type.


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## berlinonaut (30 Nov 2019)

Kell said:


> Out of interest, which stem is on the B75. I couldn’t find out online, but had assumed it was the old S type.


As you can see from the pictures of the B75 it is the old M-stem in conjunction with the old M bars.


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## Tenkaykev (30 Nov 2019)

berlinonaut said:


> As you can see from the pictures of the B75 it is the old M-stem in conjunction with the old M bars.



Just to clarify my earlier post, I have the old style (2015) M stem with old style M bars. 

JK does the old style M bars, but wider. I swapped the original bars for the JK ones, and with a bit of trimming, a little at a time, was able to fit 130mm Ergon grips. 

If you don't mind a bit of assymetry you can leave the right hand side of the bar longer for extra hardware space.


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## Kell (2 Dec 2019)

berlinonaut said:


> As you can see from the pictures of the B75 it is the old M-stem in conjunction with the old M bars.



As *you *can see... 

I, on the other hand, don't know the subtle differences well enough to say which is which just by looking.


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## DBrown67 (5 Dec 2019)

Well so far so good... now for the gearing. I've decided I want a 6 speed. Obviously the B75 only comes with 3 speed (-12%).

I rang a Brompton Junction shop (thought they'd be best placed) to ask if they could sell a B75 with 6 speed conversion as an "official" dealer done mod. They said yes and confirmed it would be around £100 to do it. They keep the original parts removed of course. But I'd get the 6 speed upgrade (-12%) with the colour I want for around £845. Sounds very reasonable to me. Saves all the messing of trying to fit a kit myself.

But would you trust a local Halfords to do this job? (for -10% British Cycling discount) I'm in Leeds and Brompton Junction in London is too far to go in person. I'd assume their deal to modify the bike would be somewhat similar.

If that deal is right I'm definitely not messing with double chain rings etc.etc.


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## Pale Rider (5 Dec 2019)

DBrown67 said:


> But would you trust a local Halfords to do this job?



No.

Putting a second sprocket on the back and routing the cable is a job for someone with experience of working on a Brompton.

Halford's mechanics are generally poor, and even if the ones in your local branch are not, they will have little knowledge of Brompton having only recently taken on the brand.

Is there not an independent dealer in Leeds?


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## DBrown67 (5 Dec 2019)

Pale Rider said:


> No.
> 
> Putting a second sprocket on the back and routing the cable is a job for someone with experience of working on a Brompton.
> 
> ...



Well I was kinda thinking like you to be fair. It might be worth foregoing the discount and just getting it from Brompton Junction and having it couriered to me. They work on them day in day out.

"Dealers" in Leeds are going to be the likes of Halfords, Evans and Cycle Republic.


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## Pale Rider (5 Dec 2019)

DBrown67 said:


> Well I was kinda thinking like you to be fair. It might be worth foregoing the discount and just getting it from Brompton Junction and having it couriered to me. They work on them day in day out.
> 
> "Dealers" in Leeds are going to be the likes of Halfords, Evans and Cycle Republic.



Will the London dealer courier the bike?

Brompton are a bit funny about protecting dealer's patches.

That's why on the Evans site it says 'in store collection only' for Bromptons.

If it has to be one of the chain (ho-ho) dealers, Evans has been selling Bromptons for years so there's a chance the Leeds branch has someone who knows what they are doing with them.


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## Kell (5 Dec 2019)

Simply putting a second sprocket on a 3-spd doesn't give you the same range as a 6-speed though.

£100 doesn't sound too bad to have it done at the outset TBH. 

I know they get to keep your parts, but a BWR hub on its own is £150. Plus the sprockets, and your time.


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## Nibor (5 Dec 2019)

You could seee if Blazing saddles at Hebden Bridge could do it they are only an hour away and a great Brompton dealer.


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## DBrown67 (5 Dec 2019)

I noticed two of you mentioned putting a second sprocket on the back. This conversion would need the entire hub/wheel replacing for the BWR so the sprockets should be fine? That's why I thought the conversion price was so reasonable. Maybe I'm confusing what you guys meant.

EDIT: Confirmed. I'd have to collect the bike from Brompton Junction in person. For a folding bike in 2019 I find this policy pretty ridiculous. So I'd need somewhere local. I think Cycle Republic might be best or try that shop in Hebden Bridge.


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## Nibor (5 Dec 2019)

Give Blazing saddles a ring they are nice people.


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## berlinonaut (5 Dec 2019)

DBrown67 said:


> I noticed two of you mentioned putting a second sprocket on the back. This conversion would need the entire hub/wheel replacing for the BWR so the sprockets should be fine?


And you were right about the need to replace the whole hub/wheel. 100£ for the upgrade aftermarket sound absolutely fair, given the cost of the parts let alone the labor time and the price difference on a new bike would already be 85£ according to Bromton's bike builder.


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## Pale Rider (5 Dec 2019)

Is the three speed hub different to the three speed hub - used with two sprockets - on the six speed?

I appreciate the shop is getting the 'old' bits, but I'm surprised they would replace the hub, sprockets, and add the extra gear changer for £100.


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## rualexander (5 Dec 2019)

Pale Rider said:


> Is the three speed hub different to the three speed hub - used with two sprockets - on the six speed?



Yes, the 3 speed Brompton uses the Sturmey Archer BSR (Brompton standard ratio) hub and the 6 speed uses the Sturmey Archer BWR (Bromton wide ratio) hub.
The hub driver is different on the two hubs too, with the 6 speed having the splined driver to take two sprockets.


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## Kell (6 Dec 2019)

I must admit, I didn't realise the hub driver was different, but as mentioned above, the 3-spd hub has a much narrower spread of gears. 

Compared to the standard 3-spd, the standard 6-spd has two gears below and one gear higher. I've had the chain pusher fail on mine before and only had 1st, 3rd and 5th gears and they were comically far apart.


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## DBrown67 (6 Dec 2019)

To be honest it's lower gearing I really want. There's a hill near me and on the lowest gear of middle ring of my MTB I still can't get up it with electric assistance turned off. That's why 6 speed -12% really appeals to me. I believe the rear sprockets can be changed to lower it a bit further still. I definitely want a <30 gear inches for first.

For me the ideal gear set up would be setting off in 3rd or even 4th and using the 4th/5th for cruising. That way the first two at least are hill climbers. I nearly always free wheel down hills, hardly ever pedal going down. The standard 3 speed I test rode was awful for me (gear wise). 1st too high and had to get off and push up nearby hills. And I never got it in 3rd.


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## Kell (6 Dec 2019)

There are definitely lots of ways to tinker with the gearing - even within the OEM options from Brompton.

I did run the 44T chainring for about 6 months as there's a hill of a hill on my commute. I've now gone back to the standard 50T chainring upfront as the 44T might have made the hill climbing easier, but it compromised the ride everywhere else.

I've also tried the 12T/16T 2-speed sprockets to see if they would work, but it made the spacing between the gears very uneven.

Very close between 4 and 5, and then a huge gap to 6th.

*For me, that is. YMMV.*


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## berlinonaut (6 Dec 2019)

DBrown67 said:


> To be honest it's lower gearing I really want. (...) I definitely want a <30 gear inches for first.


You can go for a conversion of the BWR to nine speed like I did it to add a little bit of spread to the BWR - cheap, good and reliable:https://www.bikeforums.net/20170010-post8.html and https://www.cyclechat.net/threads/anybody-installed-a-modified-3rd-gear-to-a-bwr-hub.243473/
If you want to go really short you can fit a Schlumpf Mountain Drive.
From a short gear perspective the S/A XRF-8w would also be an option - the first is very short. However - personally I never made big friends with the hub. Now it lives in my Brecki and there it does a really good job. However, everyone's mileage and taste vary.
You can add another, smaller chainring to the front.
There are a lot of ways to Rome, cheap ones and expensive ones, each with their specific upsides and their specific downsides.


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## chriscross1966 (7 Dec 2019)

100 quid for a dealer upgrade to a six-speed is an absolute steal.... if you can put up with Brompton's 6-speed system, just the derailleur system (chain pusher and tensioner, I know) is 60 quid for the parts, so charging you 40 quid for a six-speed wheel swap-out and their time, minus I guess the use to them that the old tensioner and wheel have as service parts seems OK... but.... once you've added mudguards you're up to the price of a regular M6L... which has the modern bars, shifters and more importantly, brake levers...


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## DBrown67 (7 Dec 2019)

An M6L on the Brompton site in a standard colour (no extra charge) is £1170. A modded B75 with 6 speed and mudguards is £905. That's still a big saving to get the colour I actually want. That is, of course, provided the estimate given by Brompton Junction is accurate.


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## Pale Rider (7 Dec 2019)

chriscross1966 said:


> 100 quid for a dealer upgrade to a six-speed is an absolute steal.... if you can put up with Brompton's 6-speed system, just the derailleur system (chain pusher and tensioner, I know) is 60 quid for the parts, so charging you 40 quid for a six-speed wheel swap-out and their time, minus I guess the use to them that the old tensioner and wheel have as service parts seems OK... but.... once you've added mudguards you're up to the price of a regular M6L... which has the modern bars, shifters and more importantly, brake levers...



And the folding pedal, don't forget the folding pedal.

I wonder if Brompton Junction have quoted just to add an extra sprocket on the back, rather than for a new BWR hub as well.


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## chriscross1966 (7 Dec 2019)

Pale Rider said:


> And the folding pedal, don't forget the folding pedal.
> 
> I wonder if Brompton Junction have quoted just to add an extra sprocket on the back, rather than for a new BWR hub as well.


List prices on a BWR wheel vs a BSR wheel is only 20 quid, so not exactly a huge price difference, given that a big Brompton dealer will likely replace several 3-speed rear wheels every month, so it will get used and not sit on the shelf.... that massive service tail is where the money is for the shop anyway, and a new rim and a wheel rebuild will cost you pretty much what a new wheel will, I personally would pay for the wheel rebuild but with a better rim, a lot of folks won't cos lets face it, a lot of Brompton commuters aren't "keen" owners, it's just a tool to get them to work, and to them a new part for the same price as a refurbished part is "better".....


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## DBrown67 (9 Dec 2019)

Well I contacted Evans in Leeds today and they basically quoted very similar to Brompton Junction in London, at just under £900 all in for a B75 converted to 6 speed. Even better, they gave two prices because they couldn't be sure if they could retro fit the older style gear selectors as they need to fit the +/- on the left handle bar... so they quoted to fit the newer style integrated selectors/levers and that was around £950. They offered to put this is in writing if I decide to go ahead.

I also took a colour swab in with me of the two pack paint I used on my car restoration in the summer. I knew the B75 would be close, but it's difficult to judge in a shop how close. I couldn't believe it was an exact match. Not just close, but practically *exact*.  What a coincidence! I didn't even know the B75 had been made till after I'd finished the car, yet I'd been thinking of a used Brompton, stripping it down and having it painted. Saves me a big job!


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## ukoldschool (12 Dec 2019)

It would be cheaper and better in the long run to just buy a 6 month old 6 speed and have it painted... will end up less than the £950 quoted and be a much better bike. The components on the old bromptons are really not very good


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## ukoldschool (12 Dec 2019)

https://www.ebay.co.uk/itm/Brompton-M6L-Folding-Bike/274139575893?hash=item3fd3fdf655:g:tYAAAOSwXSZd8kAm&LH_BIN=1&autorefresh=true

https://www.ebay.co.uk/itm/Brompton...sh=item2f3ac80da7:g:VN8AAOSwRiJd7LVo&LH_BIN=1


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## DBrown67 (12 Dec 2019)

Not very good components? So everyone put up with poor components yet Brompton still sold loads of bikes? I don't buy that. They are incremental improvements. Doesn't mean the older parts are "poor". And this conversion is fitting the newer shifters and brake levers anyway.

And how much do you think a professional painter is going to charge to spray the 2 pack paint? (which I cannot do). Gotta be looking at around £100-£150 minimum. Plus the time to dismantle and reassemble to do the job properly... and collecting a 2nd hand bike to boot. I think I'll stick with the B75 conversion.

I don't want to sound disparaging. I value your input. It is an option I agree. But I cannot agree on the "poor parts" and the end cost.


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## DBrown67 (12 Dec 2019)

To add to this I was about to place an order when I learned the shop was relocating. So I will have to look elsewhere now. But they were very helpful and gave me this list of parts for the conversion:

*B75* - EV363746 - £745
*6 spd wheel* - QRW3SS-BWR (9025053) - £160
*Chain pusher* - EV211447 - £10.25
*Derailleur assembly* - 102995 - £25 *(??? see query below)
Shifter (L/R)* - QGSHIFTL2A / QGSHIFTR3A (9002832 / 9002849) - £25 / £30
*Cables* - QGSCAB2DR-M / QGSCAB3HUB-M (9002764 / 9002726) - £10 each
*Sprockets* - QRSPR13DR-SHMNO / QRSPR16DR-SHMNO (9024056 / 9024070) - £5 each
*Chain* - QCHAIN102DR (9022076) - £12
*Labour cost* - £60

Deduction - 3 speed wheel - £160 back (something I'd have to sell if I did the conversion myself)

Total with updated levers/shifters: £937.25 (pretty reasonable imo)

I don't know how familiar people on here are with part numbers etc. I just wondered if anything obvious was amiss with this list. My only query is with the "Derailleur assembly". Is this the chain tensioner? Because I know the 6 speed uses a different tensioner (QCTADR) so the one on the B75 will need swapping out, but I could not find any record of the number in the list anywhere (102995).


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## u_i (12 Dec 2019)

DBrown67 said:


> My only query is with the "Derailleur assembly". Is this the chain tensioner? Because I know the 6 speed uses a different tensioner (QCTADR) so the one on the B75 will need swapping out, but I could not find any record of the number in the list anywhere (102995).



This is likely the collection of pieces that connect the pusher to the shift cable. 'Assembly' is used there and the price is about right.


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## 12boy (13 Dec 2019)

I think the derailleur is the chain tensioner...1 and 3 speeds jockey wheels do not move from side to side, but those with a chain pusher ( 2 and 6 speeds) have jockey wheels that move from side to side to help keep the chain inline with either the 2 sprockets. Actual derailleur have no movement in the jockey wheels as the whole thing moves. You could get credit for the old tensioner and the original chain should be fine. Seems pretty fair price wise. Anyway, the heart wants what the heart wants in terms of new vs used and paint colors.


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## ukoldschool (13 Dec 2019)

DBrown67 said:


> Not very good components? So everyone put up with poor components yet Brompton still sold loads of bikes? I don't buy that. They are incremental improvements. Doesn't mean the older parts are "poor".



The new components are much better than the old ones, that's why they introduced..... 
The analogy of all the people that bought bromptons with the old components is moot as they didn't have the option of newer ones....

Look its entirely up to you. You seem to have made your mind up. 
I think its bonkers, but then I also think invalid car blue is a hideous colour


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## DBrown67 (19 Dec 2019)

Picked up my new B75 today.  After all this talk of mods I decided to buy the standard bike from Halfords to get the 10% discount. I will mod the bike in stages from now on. I mat still fot the 6 speed later I don't know. Might even go electric as I've discovered that I can get a cheap kit that uses my existing battery from my MTB.

Anyway... onto 1 issue I have. Or may not have, you guys can tell me. The white suspension block on my bike is fixed solidly to the rear frame. No issues there. But when the bike is unfolded to ride the rear frame isn't tight when it clips in. There's about 2-3mm play and I can gently bounce the back wheel up and down and the release clip wobbles back and forth as I do so and it rattles. Is this correct? I must stress I have not ridden the bike at all yet. I'm in the process of putting new mudguards on it.


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## u_i (19 Dec 2019)

The rattling is about normal. The suspension block has two settings reached by rotating it around, one where the rear triangle locks and one where it does not lock at all, with the top detaching from the rest of frame as you lift the bike. The loose nature of the connection is irrelevant for riding since the top of the triangle presses against the frame when you sit and ride, compressing the suspension block.


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## DBrown67 (19 Dec 2019)

Thanks u_j... glad it's normal. Just been out on it for the first ride and deliberately went up the steep hill near me that I use as a gauge as it's basically the steepest I have to navigate regularly. The reduced gearing helped but still no cigar. Couldn't make it. I'm thinking of going 39t crank with a 15t sprocket as that's the lowest I can go on 3 speed without messing with anything else. That basically moves my gearing along where 1st becomes 2nd and 2nd becomes top and I gain a nice low down 1st I've yet to try.

*Current B75 gearing: * 42.0 56.0 74.7
*39t crank x 15t sprocket:* 32.3 43.00 57.4

I found with the B75 on my test tonight I was using 2nd on the flat comfortably but still not getting into 3rd, except on THAT downhill for a test (after I'd walked half way up) and I can tell you that was getting just a bit too spirited for me. I could lose that 3rd gear no problem and just spin out. I need to climb that damn hill!


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## u_i (19 Dec 2019)

Congratulations, obviously, belated, on the bike! I just wonder whether you might try riding the hill on some other bike, find out what gear you need and transcribe it onto the Brompton, so that you do not go through a hit and miss.


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## DBrown67 (20 Dec 2019)

u_i said:


> Congratulations, obviously, belated, on the bike! I just wonder whether you might try riding the hill on some other bike, find out what gear you need and transcribe it onto the Brompton, so that you do not go through a hit and miss.



Did that already on my electric MTB (with the power off). Being a different bike I wasn't too sure. I've tried that hill on that bike, a demo Brompton with std 3-speed and now my B75. I'll now try the limit I can go with 3-speed and if that doesn't work, then I'll seriously consider the electric kit.


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## Tenkaykev (20 Dec 2019)

DBrown67 said:


> Thanks u_j... glad it's normal. Just been out on it for the first ride and deliberately went up the steep hill near me that I use as a gauge as it's basically the steepest I have to navigate regularly. The reduced gearing helped but still no cigar. Couldn't make it. I'm thinking of going 39t crank with a 15t sprocket as that's the lowest I can go on 3 speed without messing with anything else. That basically moves my gearing along where 1st becomes 2nd and 2nd becomes top and I gain a nice low down 1st I've yet to try.
> 
> *Current B75 gearing: * 42.0 56.0 74.7
> *39t crank x 15t sprocket:* 32.3 43.00 57.4
> ...



I'm a cautious rider and going downhill at speed on my Brompton can feel a bit unnerving, especially with the state of some of the roads hereabouts. 
I've found it rides better with my basketbag fitted and loaded up. 

Of course it's extra weight to get up the hill, but it works for me.


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## 12boy (20 Dec 2019)

Re the rubber block....earlier Bromptons had no latch on the rubber block and would break in half when picked up. As far as the hill goes, have you tried standing up as you pedal?


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## DBrown67 (20 Dec 2019)

12boy said:


> Re the rubber block....earlier Bromptons had no latch on the rubber block and would break in half when picked up. As far as the hill goes, have you tried standing up as you pedal?



Standing up is never my style. Yes, I know I'm making it more difficult for myself.

Fitted a 39t chainring today which gave me a low of 37.2 It's better and I got further up the hill but still had to bail out. Next is to get the 15t rear sprocket as I'm still on the standard issue 13t. That will give me a low of 32.3. If that doesn't work then I could try the crank set off my Giant Escape 1. But I don't really want to take that apart if I don't have to. And besides, it might mess up the chain line. Is 15t the largest I can fit on a standard 3-speed hub?

The good thing is the 96 link chain as fitted to the B75 didn't need to be shortened. It rides and folds perfectly fine with the 39t chainring.

Another question I do have though.... been using Sheldon Brown's gear calculator and in the "Internal Hub" menu there are various choices for Sturmey Archer 3 speed hubs. Which is the correct one for 3 speeds fitted to current Bromptons? They all have different names/codes and I haven't a clue.


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## 12boy (20 Dec 2019)

The 3 speed hub is a SRF3. The hub has a177% range...2nd is direct drive, 1rst is 25% less and 3rd is 33% more than 2nd. The 3 speed used in the 6 SPEED Bromptons has a 256% range.


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## 12boy (20 Dec 2019)

An 18 tooth sprocket with a 50 tooth chain ring will be very close to the 39/15 tooth combo. Sprockets are much cheaper than chainrings.


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## yoho oy (10 Aug 2021)

Can shifter and brakes on B75 be replaced to match M3L? What part numbers are these? Can't seem to find it.


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## Nibor (10 Aug 2021)

yoho oy said:


> Can shifter and brakes on B75 be replaced to match M3L? What part numbers are these? Can't seem to find it.


QBRLEVAL-LH[2] = left hand brake lever
QGSHIFTR3A = right hand brake lever and shifter


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## yoho oy (12 Aug 2021)

Thanks.


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## yoho oy (12 Aug 2021)

DBrown67 said:


> Picked up my new B75 today.  After all this talk of mods I decided to buy the standard bike from Halfords to get the 10% discount. I will mod the bike in stages from now on. I mat still fot the 6 speed later I don't know. Might even go electric as I've discovered that I can get a cheap kit that uses my existing battery from my MTB.
> 
> Anyway... onto 1 issue I have. Or may not have, you guys can tell me. The white suspension block on my bike is fixed solidly to the rear frame. No issues there. But when the bike is unfolded to ride the rear frame isn't tight when it clips in. There's about 2-3mm play and I can gently bounce the back wheel up and down and the release clip wobbles back and forth as I do so and it rattles. Is this correct? I must stress I have not ridden the bike at all yet. I'm in the process of putting new mudguards on it.


Does B75 from Halfords include brompton pump? Also what are your impressions (I assume you already took it for a spin)? Have you tried higher in the range brompton model? Trying to figure out which brompton is for me...


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## yoho oy (12 Aug 2021)

There are a few hills near place I work and I see many riders with different bromptons (and all sorts of other bikes for that matter) zipping past all day long. It seems for some of them it is a bit of a challenge (they pedal leaning forward from a seat) but some of them are able to do it while seated. I am trying to see what is this related to - 6 speed broptons, higher fitness of the driver, moving inertia (just the right moment trough traffic lights) or anything else. One thing that I noticed is that it seems that B75 is not so common among the drivers. Or I would have seen it with it's distinctive color.


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## Tenkaykev (12 Aug 2021)

yoho oy said:


> There are a few hills near place I work and I see many riders with different bromptons (and all sorts of other bikes for that matter) zipping past all day long. It seems for some of them it is a bit of a challenge (they pedal leaning forward from a seat) but some of them are able to do it while seated. I am trying to see what is this related to - 6 speed broptons, higher fitness of the driver, moving inertia (just the right moment trough traffic lights) or anything else. One thing that I noticed is that it seems that B75 is not so common among the drivers. Or I would have seen it with it's distinctive color.


Perhaps they have different handlebar types. The "M" and "H" bars are higher and give a more upright position. The "S" bars are lower and give a "sportier" more aggressive position. Being in the correct gear can also make a difference, especially in traffic with constant stopping and starting, being in too high a gear can lead to having to "mash" the pedals.
There's also the possibility that some of the Bromptons you see are Electric and the Pedal assist lets you remain seated while the motor takes up a lot of the effort.
EDIT:
If there's a lot of hills locally, then you can specify a 44 tooth chain wheel which is a 12% reduction from the standard 50 toothed chain wheel and will make the hills easier to negotiate.


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## rogerzilla (12 Aug 2021)

The B75 is fairly new and is a bit of a parts bin special. Apart from the mudguards, you're not missing anything important, so it is a good choice. Most people like the colour.


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## yoho oy (12 Aug 2021)

Tenkaykev said:


> Perhaps they have different handlebar types. The "M" and "H" bars are higher and give a more upright position. The "S" bars are lower and give a "sportier" more aggressive position. Being in the correct gear can also make a difference, especially in traffic with constant stopping and starting, being in too high a gear can lead to having to "mash" the pedals.
> There's also the possibility that some of the Bromptons you see are Electric and the Pedal assist lets you remain seated while the motor takes up a lot of the effort.
> EDIT:
> If there's a lot of hills locally, then you can specify a 44 tooth chain wheel which is a 12% reduction from the standard 50 toothed chain wheel and will make the hills easier to negotiate.


London, land of bromptons... Most of the bikes I see are M bars, not electric, I think I would have spotted electric ones by their distinct front bag and motor hub. I spotted just one with butterfly type of a bar. It is hard to say from a distance how many gears these bromptons have. I would guess that most of them 6 speed. I had difficulty spotting B75 type gear shifter or it seems that there is something more going on on a left side bar than just a break handle. It is hard to see from a distance, but either most bromptons are relatively new or probably 6 speed.


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## rogerzilla (12 Aug 2021)

The current 6 speed has gears that are just about as gappy as the 3 speed, but with almost twice the range. That wouldn't make a bike faster, except down big hills. The old 6 speed had much closer gears and could be faster when ridden by someone used to a normal bike, as it is easier to find the "right" gear for the conditions.


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## alicat (12 Aug 2021)

rogerzilla said:


> The current 6 speed has gears that are just about as gappy as the 3 speed, but with almost twice the range. That wouldn't make a bike faster, except down big hills. The old 6 speed had much closer gears and could be faster when ridden by someone used to a normal bike, as it is easier to find the "right" gear for the conditions.



Just curious when the change was made? My late 2009 P6R seems okay.


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## rogerzilla (12 Aug 2021)

alicat said:


> Just curious when the change was made? My late 2009 P6R seems okay.


Late 2000s, I think, when the BWR hub became available. The old 6-speed was based on the SRAM T3, which has an internal ratio of about 1.36:1, not much more than a Sturmey-Archer SRF3, BSR or AW. The derailleur (in both types of 6-speed) fills the gaps between the hub gears and gives you one extra.


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## alicat (12 Aug 2021)

Thanks @rogerzilla. I think I've got the BWR. It seems okay to me.


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## berlinonaut (16 Aug 2021)

Tenkaykev said:


> If there's a lot of hills locally, then you can specify a 44 tooth chain wheel which is a 12% reduction from the standard 50 toothed chain wheel and will make the hills easier to negotiate.


The B75 already has the shorter gearing:



> Gear Ratio: -12% gearing as standard


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