Technique for CVT owners
Lubrication of bearings
Lubricate the foot sled bearings and the bow sprit regularly, especially after riding in the rain. The bow sprit and chrome layer can last a very long time if kept greased.
Once the bearing shells rust, there are microscopic crater edges on the running surfaces that greatly accelerate the wear of the chrome on the bow sprit.
Due to sand and regular use, micro-holes develop in the chrome from normal use; if the sprit is kept greased, nothing will rust, and everything will be fine. However, if the bow sprit is dry and for example parked wet after a ride through brine, the steel under the chrome will start to rust, and you will get rust blisters under your chrome layer. You might still ride tens of thousands of kilometers with rusted bearing shells and the steel of your bow sprit, but the rough rust surface is noisy and does not look nice...|
Slackening elastic
It has been noticed that the elastic in the bow sprit slackens quite significantly over time. At some point, for example after a year, there is so little tension on the drive cable that it becomes briefly slack during rapid acceleration, especially in the heaviest gear, while rolling back on the Snek. This can result in a slipping feeling during the next stroke; the cable first slips a bit on the Snek before it becomes tight and pulls the rear wheel. In the worst case, the cable can even lose the groove and run off the Snek. Slackening of the elastic can be minimized by parking/storing the rowing bike in the lightest gear, as this will put the least tension on the elastic. During longer breaks between rowing, for example during winter, you can completely relieve the tension on the elastic. Tightening the elastic The above-mentioned effects can be easily resolved by tightening the elastic.
- You let the two Dyneema® cords that you see on the left side of the bow sprit near the headset drop into the bow sprit; tie a thin rope or wire to them to retrieve them later.
- Remove the two elastic ends with tied Dyneema® cord from the front of the bow sprit and tie an extra knot in the Dyneema® cords to increase the tension on the elastic. You can certainly do this tightening once; maybe after a year you’ll need to renew the entire elastic.
Adjustment of the control cable
The adjustment and functionality of the control cable from the wedge housing to the foot sled are important. The outer and inner cables need to be replaced regularly, for example annually.
If you notice that pressing the clutch button is difficult, it is probably due to rust on the outer sheath of the control cable sticking to the inner cable. Besides making it difficult to shift, the opposite is also true: the wedges also have to exert a lot of force on the control cable to return to fully locked state. As a result, the wedges may not fully lock, leading to problems with the drive cable: the wedges grip the outer strands but not the core of the cable properly, causing the cable to bind and you see the core protruding from the cable. In the worst case, it can slip entirely. You need to be mindful of this, as otherwise, it means replacing the wedges and the drive cable!
Installation of new gear cables on CVT rowing bikes
- Dismantle the cap from the clutch (right thumb) button and feed a new inner cable so that the barrel of the cable lies in the plastic part.
- Feed this inner cable through the short section of outer cable, through the upper adjuster on the back of the handlebar, through 2 screw nipples (to which the second inner cable will be attached later) and then through the left adjuster at the bottom.
- Using an outer cable, lead this inner cable to the snek blocker (near the Snek gear), which locks the Snek during shifting.
- Set all three cable adjusters at the back of the handlebar to about the middle position so you can adjust in all directions later if necessary.
- Next, adjust this gear cable running backward first. Only when you have fully pressed the clutch button should the notch of the Snek blocker lever fall completely into the teeth of the snek gear.
- Once the drive cable is mounted, now adjust the 2 wedge pushers (the 2 aluminum nuts with the plastic wedge pusher inside) so that when you gently push them against the wedges (in the wedge housing), there is still about 3 mm space between the nut and the wedge housing.
- You can turn the nuts in or out with a 14 socket wrench. If you change the type of drive cable, you often have to readjust these nuts; one type of drive cable can be slightly thicker than another, causing the wedges to come to lie more outward or inward.
- Now you will mount an inner cable from the wedge housing to the handlebar; the barrel of the cable will rest in the cutout of the black plastic piece that controls the front wedge pusher. This plastic part comes out with the adjuster bolt facing outward and directed towards the drive cable.
- This barrel goes on the inside, thus in the cutout without a hollow adjuster bolt. Pull the cable end through the black cable distributor (which controls the rear wedge pusher) such that the machined opening is at the bottom.
- Feed the cable through 2 screw nipples (the 3rd cable will be attached here shortly), then through the back adjuster bolt.
- Continue to feed the cable through the flexible outer pipe, then through the outer cable to the handlebar, and when you arrive there, pull the inner cable through one remaining adjuster and through the 2 screw nipples already attached to the first gear cable.
- Now pull the wedge housing cable loosely upwards, so that both plastic parts just touch the wedge pushers. Pull the left gear cable down as far as it goes, and screw a screw nipple tight while keeping it at the middle height between the adjuster bolts.
- Now pull the 3rd gear cable through the adjuster bolt on the front black nylon block that controls the front wedge pusher.
- Feed the cable through the remaining hole on the front side of the black cable distributor that controls the rear wedge pusher and then through the 2 screw nipples. Ensure that the adjuster bolt is approximately in the middle position at the front.
- Now there is a control cable running on the right and left sides of the wedge housing; while keeping the left and right cables tight, screw a screw nipple tight while holding it in the middle of the cutout.
- Check whether the adjustment is correct; see below for adjustment.
- If necessary, adjust the cable settings with the various adjusting screws; if needed, you can also unscrew a screw nipple, adjust slightly, and then retighten. After the adjustment, also secure the second screw nipple on the handlebar and under the black cable distributor to ensure a secured connection between the control cables.
The adjustment of the CVT gear cables
- Once the drive cable is mounted, adjust the two wedge pushers (the two aluminum nuts with the plastic wedge pusher inside) so that when you gently push them against the wedges (in the wedge housing), there is still about 3 mm space between the nut and the wedge housing.
- You can turn the nuts in or out with a 14 socket wrench. If you change the type of drive cable, you may often need to readjust these nuts as one type might be slightly thicker than another, which could cause the wedges to lie more outwards or inwards.
- With the clutch button fully pressed, the snek blocker must lock (the lever must fall completely between the teeth of the Snek gear) and the wedge pushers must be fully pressed so that the aluminum hex nuts on both sides touch the aluminum wedge housing, thereby fully releasing the drive cable.
- The control cable(s) must not be too tight, otherwise, there is a risk that the drive cable will slip in the wedge housing; you will then shift unexpectedly.
- This means that in the locked state, there should be space between the wedge pushers and the nylon blocks pushing the wedge pushers. There must not be pressure applied to the wedges in the locked state; they need to be able to secure themselves firmly in the wedge housing.
- If the cable begins to slip in the clamp, try to intervene immediately; the wedges wear down quickly.
- If the drive cable is getting thinner (and the wedges wear slightly), the wedge pushers move further outward. At some point, those wedge pushers cannot move outward anymore because the nylon blocks, which are operated by the shift cable, hold them back. The wedges then cannot secure themselves properly on the cable, so they can start slipping. If slipping begins, the wear accelerates, worsening the problem. If this slipping starts, ensure that the shift cable is not too tight; but first, check whether the space between the aluminum wedge pushers and the wedge housing is adjusted correctly. You can turn the aluminum hex nuts in or out. Ensure that there is approximately 3 mm space between the wedge pusher and the wedge housing in the locked state.
How does the cable sometimes fall off?
In the early days with a CVT rowing bike, it is almost inevitable that the cable sometimes slips off. The CVT system is actually much simpler than a derailleur or hub gear; you just need to know the (operating) technique.
The cable can slip off the Snek for two reasons:
- You have shifted too lightly. This means that the returning drive cable (which is underneath) has landed at the end of the groove on the Snek (on the side with the largest diameter). If you have downshifted too far, the cable is at a standstill on the Snek. You cannot pull the foot sled back any further. If you do pull the foot sled back, the upper part of the drive cable, the section between the foot sled and the upper side of the Snek, will go slack because the lower bow pulley recoils backward, due to the cable tensioner. If there is no more tension on the cable, it can slip off the Snek.
- Incorrect shifting and/or incorrect adjustment of the control cables of the Snek. You must always press the clutch button entirely or not at all. A half-pressed shift button invites problems! The clutch button (the right thumb button) simultaneously operates the Snek blocker (the lever that falls into the Snek gear) and the release of the cable clamp on the foot sled. The control cables of these two items must be adjusted so that the cable clamp is fully released when the Snek is locked. If the Snek is locked while the cable clamp is not yet released, you will experience the same problem as described above; the bow pulley recoils when pulling back the foot sled, and the tension on the upper part of the drive cable (between foot sled and upper side of Snek) is lost, leading to it slipping off.
How do you put the cable back on:
- Stand the bike upright so that it is on its wheels.
- Put the foot sled in the rear position, thus facing the handlebar forward.
- Remove the cable from the bow pulley so that there is no more tension on it.
- Try to roll the cable tightly onto the groove of the Snek (clockwise, with the groove) from both ends, starting from the outside.
- Roll the cable from the outside (the side with the smallest diameter) of the Snek until there is tension on the cable between Snek and foot sled. This piece of cable cannot slip off anymore (if the bike is still on its rear wheel) and you can leisurely roll the other piece of cable from the larger diameter side of the Snek counterclockwise onto the Snek. Until you see that the cable is heading towards the bow pulley.
- Lay the cable back over the lower bow pulley and your bike is ready to ride.
The above may not always work because you need to roll from both sides simultaneously, which is not easy with just two hands.
A second method that is easier is to disassemble the drive cable on the wheel side of the Snek.
- You need to remove the drive cable from the bow pulley again and then give the cable at the bottom of the Snek a bit more room so that you can pull the cable end on the back of the Snek and detach the end nipple.
- Now remove this cable end completely from the Snek.
- You can carefully pull the remaining cable on the Snek a little tighter (toward the foot sled) and then carefully roll the entire cable off the Snek until it can no longer go.
- You can now start over with putting the drive cable back on. Use the same method as when laying a new cable:
- First, insert the cable into the cable clamp in the lightest gear position: Keep the foot sled in the rear position. Pull the cable that comes out of the cable clamp at the front over the bow pulley and pull the end through so that it is just past the rear axle, about 6 cm. The cable is now clamped in the lightest gear position.
- Now, while the bike is standing on both wheels, you can roll the cable tightly onto the Snek by holding tension on the cable with your right hand and turning the Snek back with your left hand. At some point, the cable will tighten between the foot sled and the rear wheel.
- After that, you can leisurely remount the other cable end onto the Snek and finally put tension on the drive cable by laying it over the bow pulley.