On this picture of ta Tiagra Derailleur on a Dahon Mu D10, there is a second threaded 10mm hole in the frame. Does anyone know what these are for? I have been unable to find explanation.

I can conjure a way to carry a separate derailleur while on tour or perhaps a place to mount the derailleur should the hanger break or get bent into an unusable way. Conceivably it might allow a longer throw derailleur.. Just not clear.

Arguably it would allow a way to "bend the frame" for the Derailleur Hanger to align better but normally you just bend the derailleur hanger itself.

These are also on the Visc D18's that I have. The Mu SL11 I have also has it.

All ears. Thanks.

I believe that's the location for folder-specific Neos derailleurs, like thus:

https://www.ternbicycles.com/us/tech/471/neos-rear-derailleur

Sidecar mount?
Steve

I will check on the Neos direction. One of those bikes at my house. I like the Chain Tensioner idea too but seems not critical to be forward like that. Love the Side-Car idea

Thank You Joe! That was it. Here is a Neos Derailleur on a Mu P8. So if we want to change we need a Hanger too. Neos are rapid rise so numbers on the shifter may be reversed too.

I need to downscake the pic before posting.

neos option

Congrats Thor for your recent life event!

Neos Derailleur on Mu P8 (also posted elsewhere re Mu D10 and Mariner - apologies for double thread)

L Arnold try elanusparts.com Will solve your problem quickly.

Surely better to have a good quality Shimano derailleur anyway. I think the Neos derailleurs were/are made by suntour/sunrace which are generally quite low end derailleurs. I understand there may be specific advantages to the Neos design with regard folding bikes but I'd take a higher quality Shimano or Sram unit any day especially the Tiagra shown above. It's rare to see a sunrace derailleur in the UK but if you do it tends to be on budget bikes. Btwin have it on their budget folding bike but a basic Shimano tourney on their higher priced model. I think I also saw one on a toys r us bike. Same as below. It's actually surprisingly hard to find suntour/sunrace derailleurs in the uk despite their shocks and chainsets being common. Whether that is quality related or just consumer resistance is debatable. Visually they don't inspire though.

I definitely prefer the Shimano Tiagra.
The Nexus is a "Rapid Rise" derailleur and pretty low profile which makes some sense on a 20" bike. I had a dual drive Mu P24 once and the derailleur component was so long it really scared me that I'd whack it just riding somewhere. (I never did and it did have an incredibly wide range of gears I must admit, especially with the Dual Drive).

There are variations in the Tiagras. I expect the "short cage" versions are better for folding bikes. I noted also that the new high end Visc D18 Disc came with a Sora derailleur set rather than Tiagra. Prior season Viscs always had Tiagra. I think Shimano is saying Tiagra is 10 speed only (Sora 9 speed) and this may be related to the shifter and displays as much as anything.

I do always notice a long Derailleur on a 20" wheel. Interesting that the Tiagra was adapted even to the 16" Dahon Eezz D3, 3 Speed Model. Cool little bike. Smallest set of cogs you have ever seen but they work well.

I sure wish we had Decathalon in the US.

Decathlon do some great stuff including some very good value bikes but they do have very low weight limits, perhaps designed with the thinner shorter frenchmen in mind. Normally their weight limits are 100kg minus the weight of the bike, fitted accessories, luggage and rider's clothes. You can end up with a user weight limit of less than 80kg on many bikes. It's very restrictive to us taller, fatter UK men. A typical US brand bike plus Giant bikes and a few others have a weight limit of 136kg for the rider alone unless a performance bike where it drops to 120/125kg. Sadly I'm too tall and fat to ride a Decathlon bike. Lightest I've been in recent years is 95kg. You might think its Decathon being overly cautious but they had to recall their Rockrider mountain bikes because the larger frames were breaking within weeks of purchase plus there was a recall on e-bikes for models that had been sold for 4 years such was the high percentage of frame failures. They cater more for the lightweight lycra brigade I guess is the point I'm making, their designs are focused on being lightweight with strength a bit like Tern, Dahon, Campagnola equipped bikes etc.

Decathalon is seemingly all over Europe. I went in one in Czech republic this summer and was quite impressed. They do very well having a narrow and functional product line that is mostly under their own brands. I did not strongly study their folding bike or bikes in general but I like their business model. It works well.

About weight limits on bikes, it is a pretty big issue seeing a 105kg weight limit on bikes, I agree. Lots of people are asking about 230-250 lbs. Americans especially.

Bummer about the frame failures mentioned. E-Bikes have their own inherent load from the motor and the Battery, plus the general weight of the rider perhaps being heavier (not an absolute).

Decathlon are huge, very successful across Europe and getting that way in the UK too I think. They could do with making stronger bikes though but then maybe that is part of their price advantage, buying lighter weaker frames means the final weight of the bike can be competitive even if many of the components are low end. I've seen bike reviews where they have stated a preference for a btwin bike because its 1/2kg less than a competing bike of similar components but the rider weight capacity was over 35kg less. About 88kg vs 125kg. Even if I weighed 80kg I'd rather have the extra safety margin unless I was a really competitive cyclist.

Decathalon have great bike clothes. No big logos! I really like that. Functional and affordable shoes and camping gear too.

I am so averse to rolling billboards. Why does cycling think its so cool to wear clothes you can't wear anywhere else?