12boy
Guru
- Location
- Casper WY USA
I would keep the FAG until it fails. Could be many years.
Let's See Your Folding Bike
- Thread starter Rockn Robin
- Start date
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- folding bike
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a.twiddler
Veteran
I would hope so. Meanwhile @berlinonaut's suggestion to fit a 14t sprocket seems good economy tip for lowering the gearing.
I keep looking at all the holes drilled in the 50T chainwheel of my Brompton and can't help thinking that surely they wouldn't go to all that trouble without them "coincidentally" matching an existing bcd standard. The crankset looks an awful lot like a Stronglight 55. Has anyone fitted such a chainring to give another, lower, gear range using the original chain set and suitable chainring bolts and washers? Just a bit curious.
a.twiddler
Veteran
Now fitted left fork folding hook, trimmed rear of front mudguard and fitted protective metal bumper, fitted rear mud flap.
The folding hook was a very tight fit with its bolt even allowing for it cutting its own thread so to avoid any chance of it splitting later I eased out the hole with a slightly larger drill before fitting to the bike, which went well.
Trimming the rear of the damaged front mudguard was straightforward using the new protective bumper as a template. Getting the assymetric one piece stay to fit after moving it up about 25mm took a lot of experimental tweaking and bending, then getting the bolts to fit the retaining plate led to wheel removal (after deflating the tyre -I'm sure it's been asked before -why no quick release on a premium bike's brakes?), mudguard removal (after removing the brake nut), reinstallation of the wheel and reinflation of the tyre. Re fitting of the stays to the bolt on attachment near the top of the RH fork, and to the LH fork end. Refitting the mudguard to the brake bolt and re centralising the brake blocks. Fortunately the mudguard was central to the wheel after all this mauling about. My fear was that this might have altered the alignment of the folding hook. Fortunately when folded and unfolded later it all lined up fine. A bit of a performance all told. Fortunately the shortened mudguard doesn't look too bad.
Can't quite see the new rear mudflap as I had to climb into a bush to get the bike in shot and the camera angle is a bit off.
The original rear mudflap (now missing) was held on by a rivet which was drilled out and replaced by a bolt, two washers, a nut and the new mudflap which all went on painlessly, with a drop of threadlock to prevent the tiny nut from disappearing.
What have I learnt? What might be a ten minute job on any other bike, on a Brompton it ain't necessarily so.
Got to get round to upgrading the handlebar area next.
The folding hook was a very tight fit with its bolt even allowing for it cutting its own thread so to avoid any chance of it splitting later I eased out the hole with a slightly larger drill before fitting to the bike, which went well.
Trimming the rear of the damaged front mudguard was straightforward using the new protective bumper as a template. Getting the assymetric one piece stay to fit after moving it up about 25mm took a lot of experimental tweaking and bending, then getting the bolts to fit the retaining plate led to wheel removal (after deflating the tyre -I'm sure it's been asked before -why no quick release on a premium bike's brakes?), mudguard removal (after removing the brake nut), reinstallation of the wheel and reinflation of the tyre. Re fitting of the stays to the bolt on attachment near the top of the RH fork, and to the LH fork end. Refitting the mudguard to the brake bolt and re centralising the brake blocks. Fortunately the mudguard was central to the wheel after all this mauling about. My fear was that this might have altered the alignment of the folding hook. Fortunately when folded and unfolded later it all lined up fine. A bit of a performance all told. Fortunately the shortened mudguard doesn't look too bad.
Can't quite see the new rear mudflap as I had to climb into a bush to get the bike in shot and the camera angle is a bit off.
The original rear mudflap (now missing) was held on by a rivet which was drilled out and replaced by a bolt, two washers, a nut and the new mudflap which all went on painlessly, with a drop of threadlock to prevent the tiny nut from disappearing.
What have I learnt? What might be a ten minute job on any other bike, on a Brompton it ain't necessarily so.
Got to get round to upgrading the handlebar area next.
Non-obvious tip (well to me anyway 
): those little luggs that protrude downwards from the rack are for hooking one chord of a bungee strap around to stop things coming off sideways https://www.cyclechat.net/threads/tips-on-brompton-rack-use.250200/#post-5653064
): those little luggs that protrude downwards from the rack are for hooking one chord of a bungee strap around to stop things coming off sideways https://www.cyclechat.net/threads/tips-on-brompton-rack-use.250200/#post-5653064
12boy
Guru
- Location
- Casper WY USA
Here's a thought....if you use a small neoprene gas line on the bolt inside the suspension block the block will compress less and not squeak.
berlinonaut
Veteran
- Location
- Berlin Germany
Well done!
But it will lead to wet feet and a shortened lifespan of the chain if ride with that in the rain.
LegendPeanut
New Member
Hi ExBrit, how do you install the QR aerobar on stock Brompton S handlebar? Because it requires a 31.8mm tube to clamp to and unfortunately, the shims add on isn't enough for Brompton S handlebar as it is measured 25.4mm diameter
Thank you
ExBrit
Über Member
- Location
- Southern California
Excellent question. As you mentioned, the manufacturer sells shims that get very close to 25.4mm - personally I think they should be included with the aerobars, but they're extra. I took two hose clamps and cut the mechanism off, leaving just the bands. I wrapped these in electrical tape to avoid scratching my black handlebars, placed them on the handlebars, put the shims over them, then attached the aerobar mounts. It was quite tricky holding about 5 things all in place while tightening the bolts but it wasn't too hard. A loop of electrical tape around the shims helps. The result is very solid.
404 Not Found Anywhere
Über Member
Seeing as I’ve posted a query about Brompton handlebars here is my 2009 S6L. Upgraded trolly wheels, Cane Creek bar ends, a Rolls saddle (I never got on with any of the incarnations of the Brompton saddle. There’s a Cateye battery light lurking in my S-bag to complement the Brompton rear light.
and to prove I’m not blinkered to other machines, this is a Dahon Mu P8 of uncertain vintage which I inherited a few years back. It rides quite nicely but compared to the Brompton the fold is awful… it’s vastly bigger and doesn’t hold together. I think the Brompton may be a tad lighter. The main frame hinge seems to have some play in it which is concerning but at the moment a tactically applied strip of insulating tape is minimising any movement. I like the Shimano 8 speed, I have it on several bikes.
a.twiddler
Veteran
Progress with my Brompton.
The high gearing was my first concern but I decided to ride it it as is for a while. Perhaps the Brompton magically transcends gear tables which apply to other bikes. It certainly rolls well, possibly due to the narrow high pressure tyres. A few short trips to the Post Office and local shops with no major gradients showed no problems though low gear had to be used unexpectedly often.
The gear ratios with the Brompton Standard Ratio three speed hub are (assuming everything else is standard) and a 13T sprocket (98 link chain):-
1st 47”, 2nd 62.7”, 3rd 83.5” which seems a bit tall if you live among even modest hills. A Brompton feature apparently. I had to take the car across town for some work so folded the Brompton which went easily in the car. After dropping off the car I unfolded it and rode home. I was all right until I crossed the river. The ride brought home the unsuitability for my needs of the gear ratios on this bike as 1st is equivalent to 4th on the Viking. I pedalled, seated, up nominally the steepest part then got my breath back along the next, less steep stretch. On the long climb up the main hill, already in bottom gear, I got fed up with it and got off and walked. Bit annoyed at having to walk after struggling in inappropriate gears and felt a bit wrung out afterwards.
Later, on going to collect the car I went through the town centre via the Library. A fairly lazy downhill despite a cold headwind. I was able to fold the Brompton and leave it in the entrance of the Library and grab some books before carrying on. I used the underpass to get across the A54 and found I had to push up the ramp to street level. Then downhill along the cycle lane to river level, and a push again for 100 yards up the other side. I actually rode the last mile to collect the car.
I don’t know what the expectation of the average commuter is but the 3 speed set up reminds me of the ratios you’d find on a 50s rod brake bike - high, too high and ridiculously high.
Followed @berlinonaut’s suggestion to use a 14T sprocket (which was free, as I had a slightly used Shimano Nexus 3-spline one in my bits box) still with the original 98 link chain which was on the bike. It fitted incredibly easily despite my fears that the retaining ring might ping off never to be seen again. I did have concerns that the differing wear rates would cause mechanical disagreements but they ran fine together.
1st 43.6”, 2nd 58.6”, 3rd 77.6” - first is slightly higher than 3rd on the Viking.
A couple of weeks later I once more had to take the car across town, for a service.
Dropped the car off, cycled back. Didn’t have to walk but the gearing turned me into a masher, and my knees ached. I would like to be in middle gear more, as it’s the direct and most efficient gear. I was passed near the top of the final hill by a teenager on a mountain bike. I caught up with him on the flat before the traffic lights and stayed with him until my turn off when he went straight on. I was still not convinced that the gearing was right yet.
Went to pick the car up. It had become extremely wet and windy in the meantime though the rain stopped as I went out. The wind was gusting from all directions. The wind eased and I flew down the long hill with no pedalling required. Something exhilarating about keeping off the brakes with fingers just hovering over the levers down this wet road. I kept looking down for the speedo which isn’t there. It might just be the impression from the small wheels but it felt to be going extremely well. I had to stop for oncoming traffic at the bottom of the hill as cars are parked both sides. On the next short steep downhill the bike once more went very well. I crossed over the river and climbed up the cycleway/ footway on the other side. It was less steep than I’d anticipated and I got up most of it in bottom gear but the bars and stem were flexing noticeably and I walked the last few yards. The rest of the route was easier, being slightly undulating. I would think that for someone bigger and stronger than me the flexiness could become a problem on steep hills. The Brompton is stiffer than the Viking which had its problems solved by better gearing, and probably this will provide the solution for me and the Brompton.
Shortly after I bought the Brompton I came across a non spider crank 44T chainset in shiny unworn condition at a reduced price which I bought “just in case”. It seemed to me that this was now the time for its just-in-case-ness to spring into action.
OK. The 44T chainwheel is on, the pedal was reluctant to come off but has now been transferred. The chain is extremely mucky, much of which transferred itself to my fingers when I took 2 links out. Would benefit from a good clean. Its 96 links run smoothly through the tensioner rollers however. Next, awaiting a test ride. The gear ratios are now:
1st 38.4”, 2nd 51.2”, 3rd 68.3” bottom is still about 2nd gear of the Viking, top is about the same as top too. The Viking has an excellent “granny gear” of 26”. I set up the gearing on this bike in anticipation of cycling home after a 12 ½ hour night shift for which it was well suited. I might not have used the super low gear on every trip but it is reassuring to know it’s there. Even though I’m now retired, if a bike can get me across town, it is well geared to take me just about anywhere. Cheshire it might be, flat it ain't. This is what I hope to do with the Brompton. The railway station is, coincidentally, on the other side of town.
Unless I start getting into extra chainrings, maybe a BWR wheel could be the way to go for a wider range, but then the temptation is there for the +2 cogs. Oh, this Bromptonitis, where oh where will it end?
Hopefully the gearing is most of the way to being sorted now.
In the meantime I have fitted Shimano brake levers, new grips, fitted bar ends then cut them down, fitted a handlebar crossbrace which happened to be in my bits box, a Mirrycle Bar end mirror and a Knog type bell. I was a little disappointed that the saddle didn't slide down as far as I expected until I realised that it had an extended seat post. There's not much point in someone my height carting about the extra length particularly as it doesn't enhance the fold. I've now fitted a used standard post and psychologically it just feels more "tailor made".
I’ve also got hold of a Brompton front bag by Radical which as far as I can tell is a C-bag. It’s so convenient that I’ve removed the Carradice bag and support, keeping it in case I need extra capacity.
The handlebar brace has proved convenient when wheeling the bike about on or off its rack, providing a central handle. Due to its width the brake clamps are mounted inboard of its fixing points, which doesn't affect the braking.
I see that one of my end plugs has fallen out of one of the bar ends. A raid on the bits box is imminent. Assuming that the test ride is satisfactory, the next thing is to look into upgrading the front dynamo light.
The high gearing was my first concern but I decided to ride it it as is for a while. Perhaps the Brompton magically transcends gear tables which apply to other bikes. It certainly rolls well, possibly due to the narrow high pressure tyres. A few short trips to the Post Office and local shops with no major gradients showed no problems though low gear had to be used unexpectedly often.
The gear ratios with the Brompton Standard Ratio three speed hub are (assuming everything else is standard) and a 13T sprocket (98 link chain):-
1st 47”, 2nd 62.7”, 3rd 83.5” which seems a bit tall if you live among even modest hills. A Brompton feature apparently. I had to take the car across town for some work so folded the Brompton which went easily in the car. After dropping off the car I unfolded it and rode home. I was all right until I crossed the river. The ride brought home the unsuitability for my needs of the gear ratios on this bike as 1st is equivalent to 4th on the Viking. I pedalled, seated, up nominally the steepest part then got my breath back along the next, less steep stretch. On the long climb up the main hill, already in bottom gear, I got fed up with it and got off and walked. Bit annoyed at having to walk after struggling in inappropriate gears and felt a bit wrung out afterwards.
Later, on going to collect the car I went through the town centre via the Library. A fairly lazy downhill despite a cold headwind. I was able to fold the Brompton and leave it in the entrance of the Library and grab some books before carrying on. I used the underpass to get across the A54 and found I had to push up the ramp to street level. Then downhill along the cycle lane to river level, and a push again for 100 yards up the other side. I actually rode the last mile to collect the car.
I don’t know what the expectation of the average commuter is but the 3 speed set up reminds me of the ratios you’d find on a 50s rod brake bike - high, too high and ridiculously high.
Followed @berlinonaut’s suggestion to use a 14T sprocket (which was free, as I had a slightly used Shimano Nexus 3-spline one in my bits box) still with the original 98 link chain which was on the bike. It fitted incredibly easily despite my fears that the retaining ring might ping off never to be seen again. I did have concerns that the differing wear rates would cause mechanical disagreements but they ran fine together.
1st 43.6”, 2nd 58.6”, 3rd 77.6” - first is slightly higher than 3rd on the Viking.
A couple of weeks later I once more had to take the car across town, for a service.
Dropped the car off, cycled back. Didn’t have to walk but the gearing turned me into a masher, and my knees ached. I would like to be in middle gear more, as it’s the direct and most efficient gear. I was passed near the top of the final hill by a teenager on a mountain bike. I caught up with him on the flat before the traffic lights and stayed with him until my turn off when he went straight on. I was still not convinced that the gearing was right yet.
Went to pick the car up. It had become extremely wet and windy in the meantime though the rain stopped as I went out. The wind was gusting from all directions. The wind eased and I flew down the long hill with no pedalling required. Something exhilarating about keeping off the brakes with fingers just hovering over the levers down this wet road. I kept looking down for the speedo which isn’t there. It might just be the impression from the small wheels but it felt to be going extremely well. I had to stop for oncoming traffic at the bottom of the hill as cars are parked both sides. On the next short steep downhill the bike once more went very well. I crossed over the river and climbed up the cycleway/ footway on the other side. It was less steep than I’d anticipated and I got up most of it in bottom gear but the bars and stem were flexing noticeably and I walked the last few yards. The rest of the route was easier, being slightly undulating. I would think that for someone bigger and stronger than me the flexiness could become a problem on steep hills. The Brompton is stiffer than the Viking which had its problems solved by better gearing, and probably this will provide the solution for me and the Brompton.
Shortly after I bought the Brompton I came across a non spider crank 44T chainset in shiny unworn condition at a reduced price which I bought “just in case”. It seemed to me that this was now the time for its just-in-case-ness to spring into action.
OK. The 44T chainwheel is on, the pedal was reluctant to come off but has now been transferred. The chain is extremely mucky, much of which transferred itself to my fingers when I took 2 links out. Would benefit from a good clean. Its 96 links run smoothly through the tensioner rollers however. Next, awaiting a test ride. The gear ratios are now:
1st 38.4”, 2nd 51.2”, 3rd 68.3” bottom is still about 2nd gear of the Viking, top is about the same as top too. The Viking has an excellent “granny gear” of 26”. I set up the gearing on this bike in anticipation of cycling home after a 12 ½ hour night shift for which it was well suited. I might not have used the super low gear on every trip but it is reassuring to know it’s there. Even though I’m now retired, if a bike can get me across town, it is well geared to take me just about anywhere. Cheshire it might be, flat it ain't. This is what I hope to do with the Brompton. The railway station is, coincidentally, on the other side of town.
Unless I start getting into extra chainrings, maybe a BWR wheel could be the way to go for a wider range, but then the temptation is there for the +2 cogs. Oh, this Bromptonitis, where oh where will it end?
Hopefully the gearing is most of the way to being sorted now.
In the meantime I have fitted Shimano brake levers, new grips, fitted bar ends then cut them down, fitted a handlebar crossbrace which happened to be in my bits box, a Mirrycle Bar end mirror and a Knog type bell. I was a little disappointed that the saddle didn't slide down as far as I expected until I realised that it had an extended seat post. There's not much point in someone my height carting about the extra length particularly as it doesn't enhance the fold. I've now fitted a used standard post and psychologically it just feels more "tailor made".
I’ve also got hold of a Brompton front bag by Radical which as far as I can tell is a C-bag. It’s so convenient that I’ve removed the Carradice bag and support, keeping it in case I need extra capacity.
The handlebar brace has proved convenient when wheeling the bike about on or off its rack, providing a central handle. Due to its width the brake clamps are mounted inboard of its fixing points, which doesn't affect the braking.
I see that one of my end plugs has fallen out of one of the bar ends. A raid on the bits box is imminent. Assuming that the test ride is satisfactory, the next thing is to look into upgrading the front dynamo light.
12boy
Guru
- Location
- Casper WY USA
Hey there, A T......if you put a JIS bottom bracket on there you will be able to run a JIS chainring with 2 chain rings. I have an 118 mm Shimano on mine with 58 and a 38 chainrings on 110 BCD crankarms. The smallest chainrings I have seen for 110 BCD cranks are 34 tooth, BTW. With a 13 tooth sprocket my range is 35.2 to 95.6, although the greasy finger shift is required to switch chainrings. Since I wax my chains they really are not very greasy. Perhaps you don't need 95.6 gear inches but I have some 6 mile grades where they are nice. I rarely use the little chainring but when it is needed it just takes a sec to use it. 29.3 to 76.5 would be the range with 50 and 34 and a 14 tooth sprocket. Just sayin.
a.twiddler
Veteran
That's useful to know, @12boy. How many links in your chain with a 58 tooth chainwheel? Looks like the tensioner can cope with the 20 tooth difference then. 50/34 and 14 with 98 links seems do-able. Off the top of my head the two ranges seem to overlap a bit but that could be an advantage -being able to go low on the big ring or high on the small ring without having to change the chain over so often. I am going to pore over some gear tables now and get the cranks off at some time to measure the spindle length. Probably going to have to get some use out of the current set up for now.
12boy
Guru
- Location
- Casper WY USA
Alas...I don't how many links but it had worked fine with the 58/38, a hub with 11, 14 and 17 sprockets and even an 18 tooth sprocket without changing the chain length.
