Fit a Bashguard-Chainring Combo Yourself

The bashguard-chainring combo has become increasingly popular in recent years. It's a great set-up for thrashing down super technical downhill sections, while still having the gears to get back up the other side. Shimano now offers double and bash combos in both its SLX and Deore groups. Both come with 36 teeth and 22 teeth rings, so you won't miss out as much on higher gears as you would if you simply substituted your outer ring for a bash guard.

Sold with a new double-specific front mech you'll have the slickest shifting double and bash combo available.

Here we look at replacing a Shimano triple-ring set-up with a Shimano double and bash clainset and double-specific front mech. Although you can get away with using a mech designed for a triple, double-specific mechs will give the best shift quality, as their geometry is adapted to follow the contour of the smaller rings. If you're using a triple-specific mech you will have to play with the height and limit screw adjustment to get the best shift.

The tools you need for this job are Allen keys, anti-seize or grease, rags, park BBT-9, cable cutters, screwdriver Phillips No. 2, chain tool, pedal spanner, inner gear cable, soft mallet, and a good amount of self-control and positive mindset.

First remove the pedals. Than undo the crank pinch bolts. Now you can unscrew and remove the end-cap. If the crank is fitted with a locking tab flick it up out of the way. Pull the crank-arm free from the axle. Tab the axle with a soft mallet and pull free from the BB by grabbing hold of the chainrings and giving them a tug.

Now un-clamp the cable from the front mech. Loosen and remove the bolt from the front mech's band to allow removal from the seat tube. If your front mech's cage is riveted together you'll need to break the chain to allow complete removal of the front mech.

If you aren't replacing the BB at least check it's tight while you're at this stage. Apply anti-seize or grease to the axle of the new crank. Fit it into the BB shell and tap it home with the soft mallet. Fit the left crank-arm and end cap. Tighten the end cap to 0.5Nm torque and then the pinch bolts to an even 15Bm. Push the safety tab into place.

Fit the new front mech. Use the sticker on the gauge to help position it. The outer cage of the mech should clear the bashguard by about 2mm.

The outer cage of the mech needs to sit parallel to the chainrings and the bashguard. When you're happy with the mech's position, tighten the clamp bolt with 6 to 7Nm and re-fit the chain. Shift into the biggest cog on the cassette. Remove the plastic alignment block if it's still fitted form the front mech and adjust the low limit adjuster screw until the inner cage of the mech just clears the chain.

Shift the front shifter to the first chainring position. Wind the barrel adjuster almost all the way in, leaving one turn of adjustment. Replace the inner cable if necessary. Correctly route the inner cable to the cable clamp on the mech. Pull the cable tight. Clamp and crimp if necessary.

Shift into second chainring and the smallest cog on the cassette. Adjust the front mech high limit adjuster until the mech just clears the chain. It may be necessary to adjust the cable tension to obtain a smoother shift and minimize chain rub. Re-fit your pedals and try you new double and bash set-up out.