Guide · Bags
Rear racks: frame fit, load limits and MIK or MTX top bags
A rack's stated load and each bag's payload are separate limits, and the lower one governs. Seatstay rack fit, carbon frames and why MIK and MTX bags differ.
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Short answer
A rear rack's stated load and each bag's payload are separate limits, and the lower one governs. Seatstay-mounted racks have their own frame requirements, and some makers do not recommend them for carbon. Top bags clip to a system such as MIK or MTX, and those systems are not interchangeable.
Two limits, and the lower one governs
Every loaded rack has at least two numbers to respect: what the rack is rated to carry in total, and what each bag on it is rated to carry. They are set by different makers for different parts. Check both, and treat the lower relevant number as your limit.
Some examples of stated limits:
| Item | Stated limit | Applies to |
|---|---|---|
| Topeak TetraRack M2 HD | 22 kg (48.5 lb) | Total load on the rack |
| ORTLIEB QL2.2 system | 12.5 kg | The mounting system |
| ORTLIEB Back-Roller pair | 9 kg | Each bag |
| Basil MIK adapter plate | 15 kg | The adapter plate |
| Brompton Front Bags | 10 kg | The front bag, carried on the frame |
Sources: Topeak,[1] ORTLIEB's Quick-Lock page,[2] ORTLIEB's Back-Roller page,[3] Basil[4] and Brompton.[5]
Two Back-Roller bags at their 9 kg each come to 18 kg, inside the TetraRack's 22 kg. Add a top bag and you can pass the rack's limit while every bag is inside its own.
Seatstay racks: frame fit
Some racks clamp to the seatstays instead of bolting to eyelets. Topeak specifies that the TetraRack M2 HD needs seatstays over 15 mm in diameter, 95-125 mm apart and angled over 25 degrees.[1] Topeak says TetraRack is not recommended for carbon forks and seatstays, and lists the M2 HD as not compatible with V-brake systems.
Before you buy a seatstay rack, measure:
- Seatstay diameter where the clamps will sit.
- Distance between the seatstays at that point.
- Seatstay angle, from the side.
- Your frame material, and your brake type.
Those numbers apply to the TetraRack M2 HD only. Another rack has its own requirements.
Top bags: MIK and MTX are separate systems
Top bags (trunk bags) usually click onto the rack through a mounting system. Two you will see:
- Topeak MTX. Topeak's MTX QuickTrack Adapter 2.0 (TRK-R045) is an adapter for its MTX TrunkBag series, listed for the E-Xplorer TrunkBag and the MTX TrunkBag DXP, EXP, DX and EX.[6] Topeak's page gives no load figure for the adapter.
- MIK. Basil lists a 15 kg maximum load for its MIK adapter plate, and says the separate MIK Carrier Plate fits carriers with 8-16 mm tubes and 100-170 mm outer width.[4] Bikes with an MIK carrier take the adapter plate directly; other carriers need the Carrier Plate.
Topeak lists the TetraRack M2 HD as compatible with MTX QuickTrack and KLICKfix/RackTime Snapit 1.0 or Vario bags.[1] That tells you about that rack. It does not make an MTX bag fit a Racktime system, or the other way round. We found no source that makes those systems interchangeable.
Front loads on a folding bike
Brompton says its Front Bags can carry up to 10 kg, and that the load sits on the frame rather than the handlebars.[5] If you ride a Brompton, see our guide to Brompton front bags and the Electric carrier block.
Before you buy
We do not list a rack or top bag on this page yet. When you shop, read the rack's total load, its frame requirements and its top-bag system on the maker's page, and match your bags to that system.
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Questions
How much weight can a bike rack hold?
Whatever its maker states for that model, and no more. Topeak, for example, lists a 22 kg (48.5 lb) total maximum load for the TetraRack M2 HD; your bags have their own limits as well.[1]
Will a rear rack fit a carbon bike?
Check the rack maker's statement before anything else. Topeak says TetraRack is not recommended for carbon forks and seatstays. If your frame is carbon, ask the frame maker or a bike shop.[1]
What is MIK and does it fit any rack?
MIK is a top-bag mounting system. Basil says its MIK adapter plate is fully compatible with bikes that have an MIK carrier, while other carriers need its separate MIK Carrier Plate, listed for 8-16 mm tubes and 100-170 mm outer width.[4]
Is MTX the same as Racktime?
No source we found makes them interchangeable. Topeak lists its TetraRack M2 HD as compatible with both MTX QuickTrack and KLICKfix/RackTime Snapit bags, which is a statement about that rack, not about the bags fitting each other's systems.[1]