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Ridley Helium Disc geometryRoad · 2024 · 6 sizes, from XXS to XL

The Ridley Helium Disc is a road bike available in 6 sizes, from XXS to XL. Stack ranges from 507 to 624 mm and reach from 374 to 403 mm. Its geometry is low and long, with a racing fit.

Stack507–624mm
Reach374–403mm
Head angle71.8–74.0°
Chainstay length405–408mm
High BBAgile rearLively

What size Helium Disc do I need?

Enter the stack and reach of a bike that fits you well and we will tell you which size is closest and how to set it up.

Compare on Fitbikefy →
XXSS 507 · R 379
XSS 527 · R 374
SS 542 · R 384
MS 573 · R 390
LS 599 · R 396
XLS 624 · R 403

Enter your stack and reach to see which size fits you best.

Geometry chart by size

Measurements in mm and degrees, as published by Ridley. The ones that matter most for choosing a size are in bold.

SizeXXSXSSMLXL
Stack507527542573599624
Reach379374384390396403
Effective top tube515525545565585600
Head tube length110130145175205230
Head angle71.8°72.0°73.0°73.5°73.5°74.0°
Chainstay length405405405405408408
Wheelbase9709709779871,0051,014
BB drop686866666363
Seat tube (method not stated)450480510540570600
Seat angle (method not stated)75.0°74.0°73.5°73.0°72.5°72.5°

Source: Ridley official website · data from 11 Nov 2026.

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Ridley Helium Disc 2024

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Stack and reach of every size

Higher means a taller front end; further right means a longer reach. The blue dot is your search.

350360370380390400410420430460480500520540560580600620640660reach (mm) →↑ stack (mm)XXSXSSMLXL

Character of each size

Compared with other road bikes. Further right means more of that quality.

XXS
XS
S
M
L
XL
Positionracing → relaxed
Steeringcalm → quick
Pedallingrearward → forward
Bottom brackethigh → low
Wheelbaselively → planted
Rear endstable → agile

Bikes with similar geometry (size S)

The closest size of other road models, by stack and reach.

ModelΔ stackΔ reach
Factor OSTRO VAM · 542026±0 mm±0 mmCompare →
Cervélo S5 · 542026±0 mm±0 mmCompare →
Pinarello DOGMA F 1 OF A KIND · 5002026+0 mm−1 mmCompare →
Pinarello DOGMA F EDIZIONE SPECIALE · 5002026+0 mm−1 mmCompare →
Pinarello Dogma F · 5002026+0 mm−1 mmCompare →
Pinarello Dogma F12 · 5302019+1 mm−1 mmCompare →
Helium Disc or OSTRO VAM? In size S they have exactly the same stack and reach (542 / 384 mm): the difference is in the frame and build, not the position.

Frequently asked questions

What size Helium Disc do I need?

It depends on your position, not just your height. The most reliable way is to compare the stack and reach of a bike that fits you with those of each size (from 507/379 mm in size XXS to 624/403 mm in size XL). The size finder on this page shows the closest size and the stem and spacers you would need.

What are the stack and reach of the Helium Disc in size S?

Stack of 542 mm and reach of 384 mm, with an effective top tube of 545 mm and a head angle of 73.0°.

Is the Helium Disc a racing or an endurance bike?

Racing. In size S its stack-to-reach ratio is at percentile 32 of road bikes: a low, stretched position.

Does it have the same geometry as the OSTRO VAM?

In size S, yes: same stack and reach. If one already fits you, the same size of the other will put you in the same position.