Solving SRAM 1x chainline offset and inner chainstay rub
By Crankworthy · Published · Updated
Chainring-to-chainstay contact on a SRAM Rival 1x is a chainline problem, not a chainring problem: either the whole crank sits too far inboard, or the ring is dished too far in for the frame. Work through it in cost order — bottom bracket spacers first, then the chainring offset, then a Wide spindle crankset, which moves both crank arms 2.5 mm outboard and takes the chainline from 45 mm to 47.5 mm 1. If the ring is simply larger than the frame’s stated maximum, no amount of spacing will rescue it.
Why it rubs, and why you should not ride it
A frame flexes under hard pedalling. A gap that looks adequate with the bike in a stand can close completely when you are out of the saddle, which is why contact often shows up as a noise under load long before you can see anything wrong.
The damage is not cosmetic. On an aluminium chainstay the ring mills a groove; on carbon it wears through the outer layers and into structure, and a chainstay is not a part you want to discover the limits of. Witness marks — bright scoring, paint dust, a polished patch on the inside face of the drive-side stay — mean it is already happening.
Gravel frames are where this bites most often. Clearance for a wide tyre pushes the chainstay outboard and up, into the space the chainring wants, which is exactly the problem SRAM built the Wide spindle to solve 1.
The numbers that decide it
Chainline is the distance from the frame’s centreline to the centre of the chainring. Every fix below is a way of changing that number, or of making the ring smaller so it clears.
- Standard road chainline
- 45 mm on a standard SRAM road crankset [1].
- Wide chainline
- 47.5 mm on a SRAM Road Wide crankset — 2.5 mm further out [1].
- Q-factor
- 145 mm standard, 150 mm on Wide. Your feet move out with the chainring, which some riders notice and some do not [1].
- What Wide actually does
- It shifts both crank arms outwards by 2.5 mm, and needs inboard and outboard spacers 2.5 mm wider to suit [1].
- DUB spindle
- 28.99 mm — the spindle standard under current Rival cranks [2].
- Road direct-mount offset
- SRAM’s X-SYNC road direct-mount ring for the 8-bolt interface is 6.5 mm offset [3]. Eagle mountain rings use 3 mm (Boost 148 mm) and 6 mm (non-Boost 142 mm) [4] — a different scale entirely.
- Rear end limit
- SRAM pairs the Road Wide spindle with a maximum 142 mm rear end; beyond that you are outside what it was designed for [1].
Work through it in this order
Cheapest and most reversible first. Each step moves the ring outboard, or moves the frame out of its way.
- 1
Check the bottom bracket spacers first
A missing drive-side spacer pulls the whole crank assembly inboard, and it is the most common cause because it costs nothing to get wrong. Pull the crank and compare what is fitted against SRAM’s spacer layout for your shell width and spindle — a Wide setup takes inboard and outboard spacers 2.5 mm wider than a standard one 1.
- 2
Check the chainring offset
Direct-mount rings are made in several offsets — how far the ring is dished relative to the crank’s mounting interface. A smaller offset puts the ring further outboard, which is the direction you want. Match the replacement to your crank’s interface and to the chainline your frame calls for.
- 3
Consider a Wide spindle crankset
If spacers and ring offset cannot find the clearance, the Wide crankset is the designed answer: 47.5 mm chainline instead of 45 mm, both arms 2.5 mm further out 1. SRAM lists it as required where the bike specifies a 47.5 mm chainline, where an Eagle Transmission is fitted to a gravel or road bike, or with the 43/30T crankset 1.
- 4
Check the ring against the frame’s maximum
Frames publish a maximum chainring size, and the clearance pocket in the chainstay is shaped around it. A ring bigger than that sits outside the pocket no matter how the crank is spaced, and the only fix is a smaller ring. Dropping from 44T to 42T or 40T nests the teeth back inside the recess; a wider-range cassette behind it gives back what you lose at the top.
Chainring offset: do not use the mountain numbers on a road crank
The 3 mm and 6 mm offsets riders quote are Eagle mountain figures — 3 mm for Boost 148 mm, 6 mm for non-Boost 142 mm 4. Rival’s road and gravel cranks use the 8-bolt interface, and SRAM’s X-SYNC road direct-mount ring for it is a 6.5 mm offset 3. Different scales entirely, and swapping one for the other turns a clearance fix into a worse rub.
Offset is the distance between the centre of the chainring teeth and the mounting surface the ring bolts to. Read the offset the ring itself states — it is marked on the back of most direct-mount rings — then check the interface it is cut for and the chainline it should produce on your crank: 45 mm for a standard spindle, 47.5 mm for Wide 1. A ring chosen off a mountain offset chart may not even mount, and if it does it sits at the wrong chainline.
The direction is the part worth remembering: a larger offset dishes the ring further inboard, a smaller offset sits it further outboard. Clearance problems want the smaller number.
Do not skip the chainring bolts while you are down there. On some setups it is the bolt heads, not the teeth, that reach the stay first — which shows as filed paint around the bolt circle rather than a groove at the tooth tips.
Crank bolt torque for refitting
Changing spacers or a ring means the crank comes off and goes back on. This is SRAM’s own figure for DUB, read from their manual rather than repeated from a forum.
| System | Torque | Tool | Source |
|---|---|---|---|
| SRAM DUB (crank arm bolt) | 54 N·m (478 in-lb)read in the manual | 8 mm hex bit socket | SRAM MTB Cranksets and Bottom Brackets user manual, p.8 |
What we stock that is relevant
The DUB bottom bracket is the part the spacer question lives on; the rest is what you need to get the crank off and back on to spec.
- SRAM DUB BSA Bottom BracketThreaded BSA 68/73mm BB for DUB 28.99mm spindle cranks$37.82Amazon
- Park Tool HXS-1.2 Pro Hex Wrench SetL-shape hex wrench set 2-10mm, workshop grade$28.95Amazon
- Park Tool TW-5.2 Torque Wrench (2-14 Nm)Ratcheting adjustable torque wrench, 3/8" drive, bit set$100.95Amazon
What this job needs that we don’t stock
Named so you can source them elsewhere — we would rather say this than point you at a product that is not the right one for the job.
- SRAM road and gravel cranksets, including the Road Wide spindle versions — our catalog carries SRAM DUB cranks for mountain only.
- 8-bolt direct-mount road chainrings. The chainrings we stock are mountain 3-bolt, Cinch and 104 BCD, none of which fit a Rival crank.
References
- 1.DUB Road Wide — SRAM service article (chainline 45 vs 47.5 mm, Q-factor, 2.5 mm spacer difference, when Wide is required)
- 2.MTB Cranksets and Bottom Brackets user manual — SRAM (DUB spindle, crank bolt torque)
- 3.X-SYNC Road Direct Mount Chainrings (CR-XSNC-DM-D1) — SRAM product specification: 8-bolt, 1x, 6.5 mm offset
- 4.Which chainring offset do I need for my SRAM Eagle drivetrain? — SRAM support (3 mm for Boost 148 mm, 6 mm for non-Boost 142 mm; SRAM’s support site blocks automated reading, so confirm it in a browser)
Related
Part of the bike upgrade and compatibility guide.