How to Convert a Single-speed Bike to Multi-speed Bike
We receive inquiries from customers on a regular basis asking for assistance in helping them convert a single-speed bike to a multi-speed bike; in other words, taking a single-speed bike, and adding a rear derailleur to the bike so that it now can use a multi-gear rear cog. Therefore, we decided to write a blog post on this subject in the hopes that a wider audience might find this information useful.
Based on discussions with experts in the industry (e.g., bike mechanics, frame builders), and reviewing posts online, the super-majority of responses end with “Buy a new bike” because, short of the bike manufacturer having a conversion kit, there are not really any inexpensive or simple options available to convert from single- to multi-speed. We don’t mean to dissuade anyone from trying, but are simply trying to be realistic, as it is generally not very easy to convert from single- to multi-speed. It can be done for some frames, but not most.
Again, the simplest option is if the bike manufacturer for your bike model already has a single- to multi-speed conversion kit available for your bike model. Some bike manufacturers, for some bike models, have single- to multi-speed conversion kits. For example, if the bike manufacturer used the same frame to create both single-speed and multi-speed variants of that bike model, then you are in luck! You can contact the bike manufacturer and they might have a solution for you. Unfortunately, there are not many bike models for which single- to multi-speed conversion kits are available.
If you decide you want to do the conversion work yourself, or hire someone to do it for you, there are two critical parameters regarding the bike you want to convert…
- Whether the rear stays on the bike are wide enough to accommodate a wheel with a multi-gear cog;
- Whether the rear dropout is of a size and geometry that it will accept a rear derailleur hanger.
Therefore, before venturing further, please make sure that your bike frame meets both of the above criteria.
If your bike meets both of the above criteria, then you have a few options to consider when completing the conversion from single-speed to multi-speed…
1) Work with a local frame builder and/or your local bike shop to modify the rear dropout on your bike to accept a rear derailleur hanger, and align the hanger as needed to work correctly with all gears on the rear cog. While this option might be a more expensive proposition, bike shop personnel and frame builders are experts in the mechanical details regarding bicycles.
2) Complete the work yourself. For those of you that want to try to do the work yourself, and (a) if the rear stays on the bike are wide enough apart to accommodate a wheel with a multi-speed rear cog and (b) the rear dropout is fairly flat along the outer surface, the easiest route to success might be using a generic derailleur hanger, such as the following, which you can purchase on Amazon (we do not carry the generic hanger)…
https://www.amazon.com/SunRace-Shimano-Compatible-Index-Hanger/dp/B001PT8M8C/
The flat, planar surface of a generic hanger, combined with a rear dropout that is sufficiently flat on the outer surface to accommodate the generic hanger, allows you to firmly attach the generic hanger to the rear dropout. You will have to be careful regarding the types of bolts or screws used to attach the generic hanger to the rear dropout, and carefully drill holes (perhaps threaded holes) to accommodate the attachment bolts or screws. You will also need to make sure that the generic hanger places the rear derailleur in a position such that all gears of the rear cog can be accessed within the range of chain placement positions available for the rear derailleur.
If you need a hanger extender (for example, because the “arm” of the generic hanger is not long enough to accommodate the larger gears on the rear cog), you can add our #3001 hanger extender to the end of the generic hanger. You can view our Hanger Extenders here…
https://derailleurhanger.com/manufacturer/hanger-extenders/
3) Customize the rear dropout to accept a replaceable rear derailleur hanger. Alternatively, you might also want to look at the following video, which shows you how to customize the rear dropout to accept a replaceable rear derailleur hanger…
https://www.youtube.com/watch?v=xlxaCif23EM
If you decide to go this route, you can purchase a couple different hanger types from us, and return the unused hanger(s) for a refund, We offer a full refund on the price of any unused hangers that you return to us, but we will not refund any shipping costs. The unused hanger(s) must be returned to us in like-new condition.
Again, none of the above is for the faint of heart. Before taking any action with the bike, you will need to carefully plan out the steps, check expected alignments, and only proceed if you believe there is a good chance of success. We highly recommend you talk with the mechanics at your local bike shop, and/or with a local frame builder. They are professionals, and can provide the best guidance regarding potential success for a particular bike. And…as many have opined online, the easiest route to success is to buy a new bike.
We hope the above is helpful.
As always, if you are in need of a replaceable rear derailleur hanger, you can use the “1-2-3” process and other information available on derailleurhanger.com to quickly find the hanger required on bike, or click on the “Contact” link on our website and we will respond quickly to provide personalized assistance
Please let us at derailleurhanger.com know if we can assist you in any way. Happy riding!