Brompton, T5, Yellow – Modifications

[gom]

Many people – here & on other forums – have posted on their Brompton modifications, which I have found very useful, especially the fitting of a front changer. So in case of use / interest to anyone, here is some information on my Brompton mods.

The bike
1999 T5 Brompton. In yellow – at the time an extra-cost option.
* 1999 – so a MK2 frame
* T5:
* Tourer / Touring : So rear rack. Originally had (bottle) dynamo lighting, but since removed.
* 5-speed, Sturmey-Archer “Sprinter” hub.
This is the single-cable, 5-speed hub, not the dual-cable one used until the mid (?) 1990s.

The rack does slope, but maybe not quite a much as these photos imply.
For the last 10+ years I had hardly used it, but this year I have started again. 🙂

 

[gom]

Brakes
The original fitted brakes were awful, so as soon as the Brompton dual-pivot brakes became available (early 2000s ?), I replaced them.
Recently (this year) I fitted the latest Brompton brake levers. For years I was using a cheap, plastic pair (not the originals). The change has made the braking so much better.

 

[gom]

Grips
This year I fitted Ergon GP3 grips – the short ones for use with twist-grip changers. These are not quite long enough. Maybe I should have bought the long ones and cut them down (if possible). As it is I have padded them out with a bit cut off some cheap grips.
Set as I like them, they do not affect the fold. The right one needs a little force to get by the front tyre, but not much.
The handlebars are the original M-bars, so the pre-2017 version.

 

[gom]

Chain
The 1/8” chain has been replaced with a 3/32”, which meant a new sprocket. The original was 13-tooth, but I have now replaced that with a 15T for the lower gears.
Using the 26-tooth chainring, the chain sits close to the chain-stay when slack. Under tension it does not look quite so bad.

 

[gom]

Front Changer
For years I didn’t use one, but this year I found various forum posts referring to the “folding bike front changer adapter” (readily findable on eBay), so I thought I’d give it a go. The adapter is designed for a slightly fatter tube, but padding with insulating or gorilla tape gives a snug fit.

The changer is the cheapest buy-at-once I could find on eBay at the time, and not really designed to work with the 3/32” chain. However, with a certain amount of bending out of the outer side of the cage (which broke off most of that side of the cage), I have got it to work. The remaining outer cage is just enough to knock the chain off the big ring, and the inner side is firm enough to push the chain over so it climbs back up from the small ring. It took a several goes to get the positioning and adjustment right, and the change up has to be done with care, but it works (at least for now).

Other changers are recommended on this and other forums, possibly even designed to take the 3/32” chain. I assume it would be better to get one of these, but for a lot more than the £10 I spent.

I’m using the SunRace friction thumbshifter to do the changing. It pulls a lot more cable than needed, but works well. The cable is cable-tied to the hub and rear-brake cables to keep it in a good position for the fold.

 

[gom]

Gear Ratios
Assuming Googling has given me the correct ratios for the SA Sprinter hub:

I could – maybe sometimes - use a higher gear, but IMO low gears are more important. ~18” is a good bottom gear for a “cumbersome”, so these look good to me. I’m not sure a bigger large chainring would be possible, the chain would need to be longer, and the changer is only just big enough for the current 20T jump.

My aim is to go cycle touring, conditions permitting.

 

[gom]

Pedals
The original RH failed long ago. The folding LH is stuck in the crank, and I can’t get it out, so I bought a second-hand crank (TA) from eBay. I believe the crank fitting is ISO (not JIS), but, as discussed on another thread, I found myself somewhat baffled in trying to determine the difference.

The RH pedal is now a MKS Sylvan Touring.
The LH pedal is a MKS EZY something, i.e. removable. To get it in the right position for me I am using a “knee saver”.
Nice to be able to fit toe-clips.

 

[gom]

Suspension
My Brompton is too old to have come with the catch which locks it in the unfolded position, so I use a bungee to stop the fold when needed. End hooks removed and cable-tied to make a loop.

The jubilee clip is supposed to stiffen the suspension.

 

[gom]

 

[berlinonaut]

Very nice and sensibly modified oldie! Just the right amount of modifications to make a massive difference, pragmatic and well proven solutions, not a single Penny spent on bling-bling! Possibly adding easy wheels to the rack and frame could be worth it as it does make a massive difference in rolling the folded bike.

 

[rogerzilla]

The first thing I would have done is to replace the 5 speed. I've generally an IGH fan but the SA 5 speed is notoriously draggy. I appreciate some people like them, though.

 

[gom]

Easy wheels are on my list of further changes, but mainly because I tend to clip the current cones with my heels. For my current usage I might find less tendency to roll better, making it easy to park the loaded bike. I shall be seeing how I get on….

 

[gom]

The first thing I would have done is to replace the 5 speed. I've generally an IGH fan but the SA 5 speed is notoriously draggy. I appreciate some people like them, though.

I rather like having an old, pre-SA-relocation hub, it adds to the pleasure of an old Brompton. Saying I have a ”T5” rather than one of the new-fangled ones in fun. I might think about it one day as I think the BWR would be good. Maybe I could sell the current hub to cover the cost? Something to think about next year, or the year after, …

 

[rogerzilla]

Oh yes, I'm not a fan of the Sunrace SA hubs. The extra NIG mechanism is flimsy and rattly, grease lubrication is annoying as it means a total stripdown to clean out wear and relubricate, and the S3X (ok, you won't find one of those on a Brompton) is a pretty bad design.

The BWR is normally used in a 6-speed setup as it has huge gaps (56%) between the gears, filled by the derailleur. Even then, the jumps are pretty large. Good for hilly country, but the old SRAM 6-speed is much better for the flatlands, with 16/17% between gears.

 

[berlinonaut]

With the bike being an MK2 ist lacks the little nut on the rear frame to add the derailleur mechanism, so neither BWR nor SRM-6-speed are much of an option.