A short-travel dropper gives an XC bike useful saddle clearance for descents without committing to a long-travel post. Our 100mm starting point is the FOX Transfer SL for low-weight, two-position operation; for a factory 120mm post, start with the OneUp V3. For 125mm, compare the FOX Transfer SL or KS LEV Integra. The Highline 3 is a lower-priced alternative where the required size is available.
100mm, 120mm or 125mm?
Choose 100mm when that provides the clearance you need or your fit limits longer travel. Choose 120mm or 125mm for another 20–25mm of saddle drop if your frame and saddle height accommodate it. The 5mm difference between 120mm and 125mm is small; fit, weight, operation and total price may matter more. Suspension travel and dropper travel are separate measurements; a 120mm fork does not require a 120mm dropper.
One model, three size boxes. Compare factory 100mm, 120mm and 125mm versions below. A model does not need all three sizes to make the shortlist. Unavailable sizes are marked clearly, and the recommendations require no travel reduction.
Check fit and the full installed cost
Confirm seat tube diameter, internal cable routing, saddle rail compatibility, usable insertion depth and your pedaling saddle height. The actuator and cable need clearance inside the frame. A post that is short enough overall may still sit too high when fully extended. Add the compatible remote, handlebar mount, cable and housing where sold separately.
FOX Transfer SL Factory
About $419 • post only unless stated
Our Lightweight XC Pick
120mm
No factory 120mm option in this model’s listed range. No shopping link for this size.
Performance
✓
Simple full-up / full-down operationTwo-position design suits riders who want quick saddle clearance without intermediate stopping positions.
Weight
✓
FOX lists starting weights of 347g / 359gFor the 30.9 / 31.6mm 100mm versions respectively; compare the exact generation and configuration.
Fit / Routing
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Internal cable routingFOX lists 380mm extended length and 80mm minimum insertion for the 100mm version. Check the frame's insertion space too.
Complete Cost
–
Lever sold separatelyAdd a compatible remote and mounting hardware to your budget.
Tradeoff
–
Premium price and size-specific fitCompare the 100mm and 125mm versions for XC use; 125mm needs more insertion space and has a longer overall body.
OneUp V3
About $270 • post only unless stated
Our Factory 120mm Pick
100mm
No factory 100mm option in this model’s listed range. No shopping link for this size.
125mm
No factory 125mm option in the listed V3 range. Choose the factory 120mm version if it fits your needs.
Performance
✓
Stop the saddle anywhere in its travelInfinite position adjustment gives more saddle-height flexibility than a two-position post.
Value
✓
A useful 120mm starting pointOur specification-based choice when you want factory 120mm drop and broad diameter selection.
Fit / Routing
✓
Internal routing and compact packagingUse OneUp's fit chart for the exact diameter and generation; dimensions differ across versions.
Complete Cost
–
Lever sold separatelyConfirm the remote, clamp, cable and housing included with the seller's package.
Tradeoff
–
Not a factory 100mm optionThis guide links the stock 120mm post only; it is not selected as a conversion to 100mm.
KS LEV Integra
About $206–$269 • post only unless stated
Factory 100 / 120 / 125mm Options
Performance
✓
Hydraulic cartridge with cable actuationInternal routing and a separate remote; select the correct diameter-specific model.
Weight
–
27.2mm: 481g at 100mm / 523g at 120mmCurrent KS published figures for LEV Integra 272; confirm the generation offered by the seller.
Fit / Length
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27.2mm versions: 410mm / 460mm overallKS lists these lengths for 100mm / 120mm travel. Do not use these figures for larger diameters.
Complete Cost
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Remote sold separatelyCheck compatible KS remote and mounting requirements before comparing total cost.
Tradeoff
–
120mm is diameter-specificA useful exact-size option for a 27.2mm frame; it is not a universal 120mm choice.
Crankbrothers Highline 3
From about $176 • post only unless stated
Budget Alternative
120mm
No factory 120mm option in this model’s listed range. No shopping link for this size.
Performance
✓
Infinite saddle-height positioningSelf-contained hydraulic cartridge with internal cable routing.
Value
✓
Lower observed starting priceA practical alternative when the available 100mm diameter fits your frame.
Fit / Stock
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Check the exact remaining variantThe linked listing has limited size choices. A low headline price is not a guarantee for every diameter.
Complete Cost
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Cable and housing listed; lever extraCompare the complete installed package with the other posts.
Tradeoff
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Not a dedicated ultralight XC designChoose it for price and fit; no verified 100mm weight is quoted here.
Which XC dropper should you choose?
For lightweight 100mm XC use, compare the FOX Transfer SL. Its two-position operation is simple, but costs more. Choose the Highline 3 when price matters more and the available diameter fits.
For factory 120mm travel, start with OneUp V3. For a 27.2mm frame needing a choice of factory 100mm or 120mm, compare the KS LEV Integra 272. The longer overall length of its 120mm version makes checking insertion and saddle height especially important.
For factory 125mm travel, compare FOX Transfer SL and KS LEV Integra. FOX suits riders who prefer two-position operation; KS offers hydraulic saddle positioning. Highline 3 is another factory 125mm model to consider when stock is available. Check the exact version’s dimensions and weight rather than applying 100mm specifications to 125mm.
Before installation
Use the current fit chart and installation instructions for the exact model, diameter and generation. Respect frame and post insertion marks, torque limits and saddle-clamp requirements. Route the cable without sharp bends, confirm smooth actuation and follow the manufacturer's service schedule.
Prefer a fixed post? See our carbon and aluminum rigid seatpost guide.
