Convert to Triple Chain Ring
Most folding bicycles come with 7 to 9 speeds. There are several bike models created specially to make room for a front derailleur, which will usually allow the rider to take advantage of the double or triple chainrings. Oftentimes, customers will ask me, “Should I consider a double or triple chainring upgrade?” I would give them this answer: “It depends on your needs because everyone is different” I usually try to provide the pros and cons below to help customers make an informed decision.
The chief benefit of the double or triple chainring is that it offers more gears. Most folding bikes, particularly the 16 inch and 20 inch wheel bikes, come with a low first gear. That means it is excellent when ridden on hills. However, they don’t have the ideal high gear for descents. So you will have to upgrade to higher gears in order to have a go downhill faster. The extra gears also allow the rider to change gear shifts in the back and down the front (double shift) or the other way around. Double shifting makes it easy to execute incremental gear changes, which is important for riders who are on a loaded tour.
This might not be a possibility on some folding bikes due to oversized tubes. You can always alter the cranks to add more chainrings on the front of the bike. However, riders might not have the ability to make a front derailleur installation to allow for a harmonious shift into the new gears. Riders should check if their bike is fitted with a front derailleur braze-on. If not, then check the tube diameter. For tubes with sizes of 28.6mm, 31.8mm, or 35.0mm, there are available clamp-on front derailleurs.
If you have no braze-on interface and just one of the usual tube sizes, you will not be able to easily install the front derailleur. However, you will still have the ability to shift the bike manually. It is normal to upshift by pushing the chain with your shoes It is more of a problem to downshift, so you will have to get off your bike and use your hands to apply the manual shift.
With the assumption that you can attach the front derailleur to the frame, you have to still run the front derailleur cable. Confirm that your frame is fitted with cable routing for the front derailleur cable. If there is no routing installed, then you will have to install housing guides.
The next thing is to decide the number of chainrings you need to add. It is usually not a good idea to add a triple chainring on small wheels. The smallest chainrings are of no use to most riders. To sum it up an interesting idea would be a double chainring for extra gears ( if necessary ).
Now for the new concerns: What crank should I purchase? What is the chainring size to use?
Most individuals should settle for the 130BCD crank because the 110BCD won't provide sufficient options for the larger chainrings. All of our Downtube folding bikes priced over than $500 are fitted with 130BCD cranks that will allow a double chainring to be installed. The tiniest 130BCD chainring is the 38T, which will be too low for most riders. The largest is the 60T, which will be too high for the majority of riders. To make a decision on the appropriate size, you are going to use of a gear calculator. Entering the different variables you will be able to make a decision on the chainring combinations to use.
Now, you will have to add a front shifter to complement your front derailleur. Grip shifters don’t’ shift as smoothly as trigger shifters and they allow you to apply the brake while changing the gear shift. Try trigger shifters, they are really nice!
To review, the majority of riders are not in need of any extra gears when riding on flat surface or climbing up hills. Nevertheless, folding bikes with small wheels will usually run out of gear when descending. It is ideal that riders be equipped with a double chainring to ride downhill faster.
Likely issues to consider when making front derailleur/shifter/double chainring addition:
1. Rear derailleurs shift more crisply than front derailleurs. So adding gears in the front will normally make the shifting less precise
2. During folding the chain may drop with a front derailleur. This is a common occurrence on multi-chainring folding bicycles. In mostly bad cases, the chain can get jammed between the frame and crank, perhaps causing damage to the frame ( if the chain gets wedged in the frame ). You may want to take precautions against chain drops to minimize the risk.