IN BRIEF
British drivetrain conversion specialist Ratio is selling a kit that gets SRAM Eagle 70 and Eagle 90 derailleurs talking to mechanical Apex 12-speed shifters. Until now, the two worlds were kept apart by a simple but decisive obstacle: an incompatible cable pull ratio. A machined fin corrects that ratio and adds an integrated cable tensioner, which opens up the mechanical T-Type drivetrain and its Full Mount hanger to drop-bar bikes. The kit sells for £70 on the manufacturer’s own shop, which bills in pounds; Canadian Cycling Magazine notes an equivalent of €65.42, worked out at the exchange rate applied at payment. You do, however, need a UDH-compatible frame, along with a T-Type cassette and chain.
| Product | Ratio Drop Bar Conversion kit for SRAM Eagle 70/90 |
| Price | £70 on the Ratio shop; €65.42 according to Canadian Cycling Magazine, at the exchange rate applied at payment |
| Contents | Replacement link, fin, rear-exit cable stop with integrated tensioner |
| Material | 6082 aluminium, CNC-machined |
| Weight | 50 g claimed by Ratio |
| Compatible with | SRAM Apex 12-speed mechanical shifters, Eagle 70 and Eagle 90 derailleurs |
| Requirements | UDH-compatible frame, mechanical T-Type derailleur, T-Type cassette and chain |
| Not compatible with | SRAM 10- and 11-speed road shifters, including those converted with a Ratio 12-speed ratchet |
SRAM may have released a mechanical version of its T-Type drivetrain last year, but it stayed out of reach for drop-bar bikes. The Ratio conversion kit, from a British workshop that makes this its speciality, has just removed the obstacle.
A pull ratio that blocked everything
The problem was mechanical, not electronic. According to road.cc, what stopped riders on mechanical drop-bar shifters from adopting SRAM’s T-Type technology is the cable pull ratio: “it’s simply not compatible”. The Canadian magazine puts it in the same terms: SRAM’s mechanical road shifters use a pull ratio different from that of the Eagle 70/90 T-Type.
Ratio’s fix comes down to a small machined wing — the manufacturer calls it a fin — which corrects that ratio, and which adds along the way an integrated cable tensioner for fine-tuning the adjustment while riding. The kit also includes a replacement link and a rear-exit cable stop. The whole lot is CNC-machined from 6082 aluminium.
What gravel stands to gain
According to road.cc, the setup lets drop-bar users enjoy “mechanical T-Type’s reputation for shifting under load — which makes a lot of sense for gravel — and the known durability of the Full Mount derailleur hanger”. According to the Canadian magazine, the drivetrain shifts reliably even under heavy load, proves highly resistant on the roughest sections, and offers a wider range than SRAM’s 1x road cassettes.
In other words: a gravel rider who wants mountain bike gear range and toughness without moving to electronics now has a route. That is precisely the space Ratio has occupied for years — not designing drivetrains, but reconciling the ones manufacturers have left incompatible.
The £70 Ratio conversion kit, and what comes after it
The kit itself sells for £70 on Ratio’s product page. Prices in other currencies — 65.42 euros, 76.34 US dollars — are, Canadian Cycling Magazine points out, worked out from the exchange rate applied at the moment of payment: they are not fixed prices set market by market.
The bill does not stop there, and Ratio makes no secret of it. According to road.cc, running the whole set-up assumes a UDH-compatible frame, a mechanical T-Type derailleur, and a T-Type cassette and chain. Ratio also states that the kit works with no SRAM 10- or 11-speed road shifter, including those converted to 12-speed with a Ratio ratchet. For anyone coming from another ecosystem, the total therefore runs well beyond the kit’s £70.
