Tour Tech: Abbey’s prototype PreHAG derailleur alignment checker 

An incredibly simple approach to a common issue.

by Dave Rome

photography by Ronan Mc Laughlin


Here’s an interesting prototype tool that CyclingTips’ Ronan Mc Laughlin spotted among the Tour pits while trying to uncover hidden marginal gains. Named the PreHAG (Hanger Alignment Gauge), this concept from Abbey Bike Tools is intended to quickly check for critical derailleur hanger alignment and/or derailleur cage straightness – all without having to undo or thread anything into place, as is normally required of the task. 

Supposedly the ingenious creation of an unnamed WorldTour mechanic, the working prototype features a 3D printed plastic construction that simply slips over the largest cassette sprocket to then form a straight line for reference against the derailleur cage. If the hanger and/or derailleur is straight, then everything will align. If the tool doesn’t align to the derailleur, then it’s time for the mechanic to pull out the derailleur hanger tool and remove the rear derailleur for further diagnosis.

Assuming it works as intended, such a tool could be hugely useful for shop and race mechanics who commonly use a derailleur hanger alignment tool when first setting up new bikes or upon diagnosing shifting issues. Similarly, the tool could equally prove as useful to casual home tinkerers who want to diagnose shifting issues without the need for a dedicated shop tool. It’s an idea that I had previously bought Tune’s laser-based derailleur tool in a hope of solving – something it didn’t succeed at. 

Abbey Bike Tools has acknowledged the PreHAG as theirs but hasn’t provided further comment at this time. However, given it’s been seen in public and even named, it seems likely that the American cycling tool manufacturer has plans to put the tool into production. Abbey Bike Tools manufactures tools in a variety of materials, and I speculate we’ll see the PreHAG machined from Delrin – a strong and chemical-resistant engineering plastic. And given the simple design, I suspect it’ll be quite affordable, too. 

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