I tried to change my cassette body from Shimano 11s (4 pawls) to SRAM XD 11s driver (4 pawls) and realized that inner spacer from Shim. won’t fit XD driver. I did this in the past without any problem. What is wrong now?
Explanation in this case is simple. Older SRAM XD drivers used to have 2 bearings inside, same as Shimano freehub has so the inner spacer was identical for both bodies. This was what happened to you in the past, where you had SRAM XD with 2 bearings so the spacer from Shimano was compatible with his XD freehub.
In your current case however, you must have a newer SRAM XD driver which comes with 3 bearings inside, not only 2pcs like it used to be in the past. Additional third bearing has taken more room inside the body so it leads to having a shorter spacer to fit in.
This is the reason why cassette bodies with 2 bearings (Shimano and older SRAM XD) need one type of spacer (16.2mm) while new SRAM XD bodies with 3 bearings need different, shorter spacer (12mm).
If you want to know the spec of both indicated types of spacers, here you are:
- INNER SPACER (LENGHT-16.2 MM) FOR B/D TYPE 4-PAWLS CASSETTE BODY SRAM-XD-2SB (2 SEALED BEARINGS) AND FOR SHIMANO BODY, 17.5x15.0x16.2 MM (PART NO: 180960)
- INNER SPACER (LENGHT-12 MM) FOR B/D TYPE 4-PAWLS CASSETTE BODY SRAM-XD-3SB (3 SEALED BEARINGS), 17.5x15.0x12 MM (PART NO: 180961)
Below picture illustrates this mentioned difference.
Speaking of spacers, let me introduce some other types of spacers that are available for Novatec cassette bodies so this way I’ll cover the entire topic.
As most of you know, cassette bodies with sealed bearings are divided in 2 main categories:
1. Bodies for 12 mm axle: A type of cassette body compatibility
2. Bodies for 15 mm axle: B/D type of cassette body compatibility (also F type, but not important for this topic).
Cassette bodies can have 3 pawls or 4 pawls so all these facts decide about types of their inner spacers. These are the specs of spacers you may see/need for your cassette body (in addition to 2 specs mentioned above):
- INNER SPACER (LENGTH-16 MM) FOR A-TYPE CASSETTE BODY 15.0x12.0x16.2 MM (PART NO.180032)
- INNER SPACER (LENGTH-16 MM) FOR B/D TYPE 3-PAWLS CASSETTE BODY, 18.0x15.0x16.2 MM (PART NO: 180192)
- INNER SPACER FOR 3 PAWLS - A TYPE SRAM XD CASSETTE BODY, 15.0x12.0x12.9 MM (180034)
Below are some pictures showing the differences among mentioned inner spacers.
1. Spacers for 3 pawls and 4 pawls type of cassette body have the same length but the difference is in thickness of spacer (body with 4 pawls needs slightly thinner spacer than 4 pawls type).
2. Spacers for A type and B/D type cassette bodies are very easy to distinguish from each other as they are meant for different inner diameter: 15 mm vs 12 mm.