I have a Decathalon BTwin MyBike.

I plan to add a 7-speed freewheel gears

I've seen MyBikes with a 6-speed freewheel,

was wondering if 7-speed is possible

  • What result do you hope to gain from this? One extra gear is minimal upgrade and comes at the cost of replacing the shifter and possibly the rear derailleur as well as buying a 7 speed freewheel.
    – Criggie
    Commented Jan 15 at 0:42
  • 2
    I already have a 7s kit, which i want to install. 6s freewheel costs more than a 7s freewheel here, almost 2x Commented Jan 15 at 4:50

1 Answer 1


Quite often you will find that it fits with no modifications, as most modern hubs for freewheel are designed with 7s in mind.

However,it's not guaranteed and you might find the chain runs close enough to the frame to mark the paint or that wheel removal and fitting is made more difficult.

If there are problems, adjusting the axle spacing (taking a 1mm spacer off the non-drive side and installing it on the drive side), then adjusting the wheel dish, could fix this. But this is a maybe more advanced, certainly more time consuming, operation.

Note: Frames with an OLD (rear spacing: over locknut dimension) of 130mm+ are "modern" and suitable for 7-12 speed with the right supporting equipment. It is likely your bike falls into this category.

  • The rear frame size is approx. 6". Though that would need to be expanded a bit to roughly 7"-7.5". This is the bicycle Commented Jan 16 at 11:37
  • @MellowMonk Take out the rear wheel and measure the gap where the hub bolts in, in milimetres please!
    – Noise
    Commented Jan 16 at 18:29

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