2_i 

Market for parts and accessories for folders aimed at lightening them or extending their capabilities is substantial. Yet many of the items are not designed or tested with the scrutiny typical for OEM, as production volumes are small and manufacturers hard to trace. When purchasing such items it is often hard to figure out details in the offer and reviews are impossible to find. Most items are more expensive than OEM and in practical use they may pretty well turn out to be unusable. Presumably we should have some space to warn others if we burn ourselves.

One could think about posting praise too, but then often items look good at the beginning and problems begin to emerge in long-term use. On the other hand, if something turns out bad it cannot be reversed with time, unless of course, the item was incorrectly used.

In any case, in the context of Brompton, I can immediately give 3 examples.

2_i 

Proper securing of hinges on a folder is pretty critical. Yet manufacturers can come up with something so ridiculous as aluminum bolts securing the hinges. In the case of Brompton I came across such a product (below) sold under Parsche brand. The bolts were additionally thinned at places to add some functionality. The product has since disappeared from the market, but from the description I fear that there are other offerings around with alu bolts for hinge clamps.

bikebikebike

Yep. Foldies have mechanical disadvantages that often make them relatively heavy in order to have necessary stiffness and ride.
I would love a 18lb 10speed folder, but have yet to see a rugged one.
Relatively unknown Mfrs do not inspire confidence, if you have been around enough to see what a part failure can do.

2_i 

Chain pusher on Brompton moves upper tensioner pulley to direct chain on one or another cog. Aftermarket pushers are equipped with rollers there to reduce friction of the pusher claws against the pulley. You can get such pushers out of Ti, alu and carbon. The rollers vary between steel and POM I think.

On a stand the rollers indeed work well ensuring accurate shifting. Unfortunately, the real life situation is dynamic: the chain pushes against the pulley, the tensioner arms flex, chain jumps around. The end of the roller directed towards the pulley presents an edge that the pulley can catch. The chain let loose can push against the other edge of the pulley and escape from the space between the pulley and pusher. In fact after a while I found it impossible to end a ride without the chain escaping and taking the derailleur out of operation. I tried both original Brompton pulleys and aftermarket with the same effect. Complete disaster.

One of the photos shows the situation after a ride, with the chain having escaped the upper pulley. One other illustrates the catching of an edge of a pulley against the roller.



A Ti Pusher with Rollers


Catching an Edge


Chain Out Free

Raxel

The tensioner arm may flex a bit but the shifting pulley axle cannot flex that much, unless one of bolt is loose.

2_i 

The chain transmits a lot of force - after all it propels the bike. The pulley axle bolt provides quite a bit of leverage. I know that it can be hard to believe, but every time this Ti Parts pusher is put on the bike, the chain will free itself mangling on the way the tensioner pulley. The only question is whether this will happen before the next corner or two more blocks into the ride. I put the pusher on and took it off and swapped the pulleys. I can leave a loose bolt once in a blue moon, but not every time this pusher goes on. The chain never ever freed itself with the original pusher that is now back on the bike - for now everybody lives happily until I try another junky aftermarket part By the way, as may be evident from the photo, the width of the pulley fills in practice completely the space between the rollers. You can only create an opening for the chain to escape by pushing the pulley away, nominally kept put by the tensioner arm.

FolderBeholder

Same experiences Ive had with third-party aftermarket motorcycle, scooter and even auto parts. You always seem to give up something to get the advertised benefit with those custom “high performance” bits and pieces. That something is usually reliability.

At this point in my machine career, I typically keep things stock for the VERY types of reasons listed above.

Schwinnsta

Be careful about substituting titanium and aluminum with bolts. In many cases steel is needed for strength.

2_i 

I learned the hard way that in some particularly demanding situations even stainless steel may need to be avoided as too brittle.

Numerozero

I bought an "Acceoffix" titanium spindle bottom bracket off Chinese Ebay seller. Says comes with "two kinds of TI bolt, black or silver".

Picture shows damage to bolt when my hand slipped while tightening. Um, no, it's definitely not titanium. Aluminum.

To be fair, the ad never said the bolts are titanium, only that they are "TI". Hmmm...

Note damage to "TI" bolt on left.


Spindle is titanium though. This pic is after being installed and then removed.


OTOH, the bottom bracket spindle is Titanium, and it does save about 150 grams. Just use steel bolts...

dahoneezz

See video at minute 5:50. He seems to think that the metal mod is introducing problems.

Raxel

Aluminium crank bolts are just fine BUT you should fasten the crank using STEEL BOLT FIRST.

And that very bottom bracket is not recommended for heavy riders. I saw a number of failure cases. But I have seen people even ripping Shimano two piece cranks though.

Raxel

Here are ultimate tensile strengths of different materials (according to Matweb homepage)

6/4 titanium alloy: 900Mpa
3/2.5 titanium alloy: 862Mpa
316 stainless steel: 538Mpa
4130 steel: 560Mpa
1018 steel: 440Mpa
7075 Aluminium alloy: 228Mpa

Most titanium bolts are made of 6/4 Ti alloy BTW.

Schwinnsta

Yes but high strength steel bolts in Mpa

Grade and MaterialMechanical Properties


Class 8.8 Medium carbon steel, quenched and tempered 830

Class 10.9 Alloy steel, quenched and tempered 1040

Class 12.9 Alloy steel, quenched and tempered 1220

2_i 

The upper tensioner pulley in 2/6-speed Brompton is moved by a pusher to make chain move from one sprocket to another. The original pulley is out of one solid piece of plastic which can rub against fingers of the pusher if the system is not tuned perfectly, which shaves over time the sides of the pulley. With this aftermarket alu pulleys where the teethed part of the pulley that engages the chain is separated, and rotates on a bearing, seems like a big improvement. The problem is that the remainder of the pulley with sides that retain the chain can be made very thin, presumably to save weight.

Take the pulleys from Best, possibly sold under other brand names too. The retaining sides are in the form of thin circumference rings supported feebly just at 3 points around the pulley. The chain obviously fights against the retaining rings and the latter get bent. As the pulley sides, here the thin circumference rings, are grabbed by the pusher to switch gears, the shifting goes to hell. To function well, the pulleys must have strong retaining sides.



Marketing Photo of Best


Beat Up Best (?!) Pulley


Shifting Depends on the Angle around the Axle This Pulley Takes

Schwinnsta

I am thinking about getting this. H&H seems to do nice stuff.

2_i 

I bought this pusher at some point and resold it without even trying to put it on. The rollers are plastic which for this small diameter is an issue. The rest is out of alu that, in my view, will not hold its ground in any serious glitch.

Schwinnsta

Thanks for the info.

2_i 

Maybe one more thing, small scale but maybe telling. I put on H&H Pulley Extension Shaft Screw Set for 3 Speed, small $ item. However, with this on, the H&H cap for the upper pulley axle was hitting the spokes hard. I think H&H Design stumbles like others. I made my own extension, even before realizing that there was one on the market, but got the H&H anyway, curious whether there was some detail there that I have not thought about.

Schwinnsta

Its something that I don't really need but thought that having side bearings would better than metal guide.

2_i 

Myself I went back to the original Brompton pusher. However, in fiddling it became apparent that shifting, particularly for 3 cogs, can be well improved over that with the original Brompton components. I know for sure that it can be achieved with aftermarket pulleys, or even one top pulley, where the teethed middle moves independently on a bearing. In the latter situation the sides quit moving at all, so there is no need for any rollers in the pusher. Still a pusher with rollers may have a potential to be more precise.

The above is from using the Best pulleys at those times when they were straight. I ordered pulleys with seemingly stronger sides than Best, marketed under ACE. They have no holes on one side, for crud dropping out, seemingly to put graphics there, but I can drill such holes mimicking what is on the other side. At this point I am 3 weeks away from my base, though, and I will be able to tell whether the plan pans out only after returning.

Schwinnsta

Update us.

2_i 

With aftermarket pulleys, presumably plastic rollers can work fine, since there is not much rubbing expected then against the pusher. However, myself I would like to keep an option of falling back onto the original Brompton pulleys if something went wrong with the aftermarket ones.

Once I stabilize the setup, to the extend that I can draw conclusions which way it went, I will post.

ttakata73

I would avoid the Hylix carbon wheelset for the Brompton. The hub is wider so requires a cut down chain tensioner. Then mine had uneven spoke tension leading to broken spokes. Then bike shops can't tension them because you can't fit a spoke tension meter onto such short spokes. So I had to buy a wheel truing stand and modify a spoke tension meter to get everything right.

For the Birdy gen3:
Ridea stem hinge lever hole doesn't line up with spring pin so needed to file a larger hole.
MultiS aluminum kickstand broke because tube is too thin/weak to support a bike.
Colorplus kickstand doesn't have alignment bolt hole and tiny rubber foot makes standing on soft grass impossible and shears off easily.

I would not recommend modifying bikes with non OEM parts unless you have a good understanding of material strengths and design. It might look pretty but it might fail leading to injury. I wouldn't use aluminium bolts anywhere on a bike.

2_i 

I tried a titanium kickstand for Brompton sold under 3Sixty brand (might be other names too) and it was meager. A Minoura stand was OK. However, absolutely the best turned out to be the kickstand mounting on the chainstay, available for $5 or so, SH included, see the photo below. Critical was using a single cut of a hose for padding the clamp, to prevent kickstand rotation, rather than traditional windings of tape or tube. Another key element was to use a ratcheting bolt to adjust the kickstand length, so the adjustment could be done in the field. These bolts (SS/Ti) run for a few $ of their own on Ebay and are usually sold in the context of photography. I now keep a stock of such bolts as they are absolutely handy on the bike. Such a kickstand should work on most folders. The chainstay mounting is convenient for stability of a parked bike as the kickstand can be pushed forward rather than be hostage by the rear axle.




Kickstand that outdid all other on Brompton

P.S. There was also a Kamoya center-mounted stand there. The concept was interesting and the machining was good, but it was not much as a stand... The statistics for those aftermarket parts is not good at all.