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All DOWN Cycles MTB NewsMain MTB NewsLocal NewsTech Tips & Reviews
Tech Tips & Reviews
09/06/06
English (US)  
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Professional Tweaks, Tips & Reviews By "AJ" Picarello
I hope you find my Tweaks and Tips section helpful. If there is something you want to know about, send me an email and I will try to add that to one of my upcoming articles.

The downhill chainguide is the most important and most abused component on a DH bike. For years, engineers have been floundering with designs that try and prevent chain derailments. Most were overly complicated or simply to flimsy to hold up under the rigors of DH. Lucky for us, we have: Bob (“Mr. Dirt”). He has been coming up with ingenious designs since the beginning of time. He invented the “Gizmo” back in 2000 and has reintroduced a new improved version this classic guide.

Dirt Gizmo

[More:]

Dirt Gizmo

The original Gizmo, actually worked trouble free and fit any style bike frame. I didn’t see much room for improvement except that 5 bolt 110mm was the one and only bolt pattern available. The Gizmo’s bolt pattern never changed with the times and may have been the reason it went extinct. Maybe Bob from Mr. Dirt was fed up with our industry not having any standards, still an ongoing problem. (I have original 5 bolt 110mm Gizmo chainguides on closeout!)

Chainguide rollers need maintenance. The original Gizmo, with no rollers at all, was no exception. I feel routine cleanings discouraged riders from staying with the Gizmo. Keeping your guide running free was both a blessing and a curse to the design. The blessing: The Gizmo used no moving pieces and if kept clean, would never fail. The curse: Easy as it was to keep clean, lazy riders, or riders that were not mechanical, bad mouthed the design and complained of excessive chain friction (always do to contamination or improper set up). I must admit, during sloppy Mud races, keeping the original Gizmo running smooth could test the patience of any racer/mechanic. (Interesting to note, chainguides that offer bearings also require general maintenance have bearing failures when riding in wet conditions).

For the past few years, Bob at Mr. Dirt seemed disappear from Radar. I was told he was designing break away Moto levers and moved away from the world of DH. Companies like Evil/E13, Black Spire, TruVativ and others seemed to take his piece of the pie and run with it. It’s a shame, but spotting a Gizmo these days is like seeing Bigfoot.

I’m happy to tell all that, Mr. Dirt is back and has found ways to refine the Gizmo! Hopefully this article will inspire new skoolers to take a look see. I couldn’t resist testing the new guide. I mounted the DH version (42T) on my Demo EC-D (now for sale listed under “Demo/Used Bikes”) and got to work.

The new Gizmo DH will work with the new 4 bolt 104mm pattern and will fit 42T-46T chainrings. Mr. Dirt also offers a smaller guide for riders that use a 36T-40T front chainwheel. The Gizmo uses the original standard (smaller diameter) ICMS chain guide mount. This time around, the guide runs on sealed bearings. The bearings are very small and like other guides that use sealed bearings, will require some attention.

No mistaking a bike with a Gizmo, the rollers are sandwiched inside bright yellow plastic guide plates and the alloy bash is lettered in white over black. I love that the inner plate completely prevents the chain from falling off to the inside of the frame (a change from the old design). I can’t see any way the chain could derail off this guide!

While pedaling, I immediately noticed a tolerable vibration coming from the upper bearing. I feel Mr. Dirt should have kept the original style upper system from the original Gizmo and used the new bearing design only on the lower roller. This vibration is really my only complaint and is ever so slight.

I’ve seen unexplainable chain derailment problems on every guide on the market today. No problems with the Gizmo! It has run trouble free, other than cleaning and greasing of the bearings after mud rides. The bearings are very small, much smaller than the competitions. Inspection of these small bearings is a must. My bearings stopped spinning after only three mud days.

The Gizmo is a very well designed chainguide. It will do the job it’s intended to do; keep your chain in place. The plates both inner and outer are very durable and will withstand the nastiest hit. The lower roller runs up tight against the bash and is the lowest profile roller I have seen, thanks to such small bearings. It is very unlikely that you will hit the lower roller on an obstacle. As any DHer knows, hitting the lower roller will rotate your guide rearwards. The hit could ruin a race run or crack your frames ICMS mount.

Far as I’m concerned the Mr. Dirt Gizmo is the best guide on the market today! I feel it has some room for improvement, but has the other brand guides beat. Bob, if you read this: Please consider removing the upper bearing and redesign this area. Maybe use the original upper guide. Also, please reintroduce the original side plate covers that give easy access to the rollers internals. These access plates make cleaning a cinch and for some sad reason have been eliminated from the new Gizmos design.

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