
Ideas: One calliper brake and one disc brake. Each with its own lever. The bar clamp for second lever could fit close to the existing bar clamp, and the lever tilted below the existing lever. Thus, if cable fails, then its lever will be slack, therefore, the hand can squeeze the lever below it - without needing to change hand position at speed.
Second idea: Use one front lever for both cables, using a twin-cable lever. Problem - existing levers include gear change, and has one single brake cable. So, more costly to replace parts.
More ideas are welcome