Sunday, May 26, 2013

How to Adjust Shimano Shadow Plus RD

About 1 month ago, I wrote about the Shimano Shadow Plus rear derailleur, and how it can be converted from a standard dropout mounting to a Direct Mount dropout. In this second part of the article, I will describe briefly how to adjust the clutch mechanism in the Shadow Plus RD.

The RD that I am operating on is the new SLX Shadow Plus RD, model number RD-M675. The construction of the clutch mechanism is quite similar to the XT and also upcoming Deore Shadow Plus RD. The mechanism is slightly different from the top-end XTR RD, but the adjustment principle is the same.

Before adjusting the clutch mechanism, set the switch to the OFF position. This is to release any spring tension in the clutch mechanism and to make it easier to adjust the mechanism.

Clutch switch in the OFF position

Before we go further, I am sure you want to know what you are adjusting! Sorry for not making that clear right at the beginning. What we intend to adjust on the Shadow Plus RD is the amount of resistance in the clutch mechanism. The clutch mechanism works by creating resistance to the RD cage movement. When traveling over rough terrain, the whole RD bounces around, and the bottom of the RD cage tends to swing forward/downward, causing a loss of chain tension and subsequently leading to chain drop.

When the one way clutch mechanism is turned ON, the cage resists any forward/downward movement, while still allowing the cage to rotate backwards easily. This ensures that chain tension is maintained, greatly reducing any chance of chain drop.

The downside of having a strong clutch is a higher shifting force at the shifter. Therefore, it is good to be able to adjust the clutch mechanism. Too light, and the clutch mechanism will not be effective in preventing chain drop. Too heavy, and it will be tiring to shift gears. The optimal setting is when the amount of resistance is just sufficient to prevent chain drop, while also minimizing the effort required to shift gears.

When adjusting the clutch mechanism, it is OK to leave the RD on the bike, as long as the switch is set to OFF and there is no pedaling.

The first step is to remove the 3 bolts securing the cover to the RD.

The 3 bolts on the cover of the clutch mechanism

Once the cover is removed, the clutch mechanism can be seen clearly. How it works: When the switch is turned from OFF to ON, a metal clamp band wraps and tightens around the one way clutch, creating resistance to cage movement. The tighter the clamp band, the more resistance there is. Therefore, what we are adjusting is the tightness of the metal clamp band.

One way clutch in the middle, with metal clamp band wrapped around it. Adjustment nut can be seen at the top left corner.

Adjustment nut located on the left side of the mechanism.

Turn the adjustment nut to adjust the tension on the clamp band. Turn the nut in minor increments, as even a quarter of a turn can cause a significant difference in resistance. It is difficult to judge exactly how much tension is needed, as the bike is not in an actual riding condition. For myself, I set the tension such that when I pull lightly on the cage, it does not rotate.

When doing the adjustments, avoid poking around the rest of the mechanism. If grease gets into places where it should not be, it may cause the clutch mechanism to malfunction.

Different riders on different terrains will need different amounts of clutch resistance. As I do not foresee myself going on super rough terrain, I will not need very high clutch resistance. In the end, the only way to find the optimum setting is to go for a ride, and make adjustments depending on the result. If you find yourself still getting chain drops, you may need to increase the resistance. If you get zero chain drops, you may have found the optimum resistance for yourself. You can even try reducing the resistance slightly, to reduce shifting force while ensuring that the clutch mechanism is still effectively preventing chain drop.

After adjustment, remember to close the cover, making sure that the rubber seal sits properly in the groove around the cover. Tighten the 3 bolts and you are good to go!

Recently I had the chance to see how well the clutch mechanism works. On a long flight of stairs, some of my friends took turns to ride different mountain bikes down the steps. As you can imagine, riding a hardtail MTB down a flight of stairs can be really rough, dangerous even. On other MTBs without the Shadow Plus RD, the chain often dropped off just halfway down the stairs. By the bottom of the stairs, all the MTBs already had dropped chains.

For my Polygon MTB, it was first tested with the clutch mechanism OFF. This meant that it functioned just like a normal RD. As expected, the chain dropped off the gears by the time the bike reached the bottom of the stairs. We then tried the run again with the clutch mechanism set to ON. The results were pretty amazing.

Looking at the RD as the bike went down the steps, it is clear that with the clutch mechanism ON, the RD only bounced slightly, preventing any loss of chain tension that would cause chain drop. When the clutch mechanism is OFF, the RD would swing wildly, with the chain whipping about furiously and eventually dropping outside the gears.

With this easy experiment, it can be clearly seen that with the clutch mechanism activated, the chance of a chain drop is greatly reduced. Although the shifting force is increased, it is a small price to pay for chain security without the need for any external chain retention devices. The ability to turn the clutch mechanism ON or OFF is also very useful. When traveling on smooth roads, the clutch mechanism is not required, and thus setting it to the OFF position will reduce shifting force. It only needs to be turned ON when tackling rough terrain.

After reading this article, you should have a pretty good idea on how the clutch mechanism works, how to adjust the mechanism, and why it is useful. Depending on your riding style and terrain, you may find this Shadow Plus feature very helpful in preventing chain drops.

Sunday, May 19, 2013

Installing FNHON Handlepost for Dahon Bikes (T-shaped, 31.5cm, Silver)

What you see in the title is not a typo error. Yes there is a bicycle brand called "Fnhon", and it is no surprise that they produce parts similar to Dahon bikes. From the name, it is obvious that it is a knockoff brand, but the quality seems to be pretty decent. In fact, it is getting popular in China, where there is a really hot market for folding bikes, with countless brands of folding bikes popping up.

I got to know of this brand through reading bicycle forums based in China/Taiwan, such as Mobile01 or 77Bike. From other people's reviews, this brand seems to be one of the better knockoff brands that are similar to Dahon.

Of course, there are many many brands that attempt to copy Dahon, making frames that look so alike that the only difference seems to be the colour and graphics. However, what makes Fnhon stands out from the rest is that they actually take Dahon's designs and improve on it, adding features and specifications that Dahon does not have.

For example, mounting the FD on Dahon bikes have always been troublesome, especially if the frame does not come with the FD mounting bracket. For Fnhon, what they improved on is that all their frames come with the FD mounting bracket AND also the cable stopper for the FD outer casing. This makes installing the FD and the cabling a breeze, as easy as installing the RD system.
The outer casing stopper located on the rear of the Fnhon frame seat tube. 
Simple but useful addition!

Another Fnhon component which I am impressed with is the handlepost. Although Dahon was the first to come up with the ubiquitous Dahon handlepost design, what I feel is lacking in Dahon designs is the choices available for the end user. For example, their T-shaped handleposts (such as on Speed Pro TT, Vector X27) are all outward folding only, and of only one height.

Fnhon saw a chance and came into the market, offering different handlepost specifications. Just to list a few, Fnhon has 1 piece, inward folding handleposts of at least 3 different lengths. Besides the different lengths and different colours (silver and black), there are also various mounting methods for the handlebar. You can choose between the T-shaped type (where you need an additional LitePro Stem), the popular quick release type (same page as the LitePro Stem), and a new bolted type. To see more, check out this Taobao page.

Warning: Very poisonous page for bike upgrading!

For my Dahon Boardwalk and Vitesse bikes, the handleposts are both of the inward folding type. Due to the special folding method that I use to fold the bikes, inward folding handleposts give a more compact fold with bullhorn or drop bars. This method also ensures that all the vulnerable parts such as the RD and shifters are on one side of the bike, and you can lean the bike on the other side safely. This are the reasons why I only use inward folding handleposts on the Boardwalk and Vitesse.

However, inward folding handleposts from Dahon are rather limited in choice. Besides the 2 piece handlepost on the Vitesse (which can be flexy and creaky, and may rotate if not tightened properly), and the Mu Uno handlepost on my Boardwalk (which is rather long), there are no other options from Dahon.

Therefore, when I came across the Fnhon range of handleposts, it felt like Fnhon has exactly the type of handleposts that I need! 1 piece, inward folding handleposts that are light and stiff.

This handlepost is meant for the Dahon Vitesse, to upgrade from the stock 2 piece handlepost to this 1 piece handlepost. Let us first take a look at the new Fnhon handlepost, and then a comparison with the Dahon handlepost to see the differences.

Fnhon T-shaped handlepost, 31.5cm length (excluding height of bottom section), silver colour.

Closer look at the T-shaped top and the Fnhon logo

My first impression of the handlepost is that it is rather well built. From the feel of the surface treatment and the welded joints, it looks just as good as Dahon handleposts. The hinge is also solid with no signs of excessive play.

Next, I took out the stock 2 piece handlepost from the Vitesse and compared it with this new handlepost.

Fnhon handlepost with the old type of safety latch

Dahon handlepost with the automatic safety latch, better but at a higher cost.

 Fnhon handlepost with a simplified construction of the latch mechanism. Instead of using a bolt with opposite left and right hand threads for adjustment, it was simplified to a long bolt that can be adjusted from the outside.

Adjust the tightness of the Fnhon clamp using an M4 Allen key from the outside

Dahon handlepost with the special oppositely threaded bolt, requires a wrench for adjustment.

Closer look at the Fnhon latch mechanism. Simple and elegant mechanism.

 The original Dahon latch mechanism. Ingenious, but comes at a higher cost than the improved Fnhon mechanism.

The base of the handlepost looks similar

Of course, a weight comparison. 521 grams for this Fnhon handlepost.

The stock 2 piece Dahon handlepost, 752 grams.

The most significant difference of all is the weight. The Fnhon handlepost is about 230 grams lighter, which is 30% lighter than the Dahon 2 piece handlepost. This dramatic reduction in weight is due to the absence of clamps on the top and in the middle of the handlepost, and the 1 piece construction.

Placing the handleposts side by side. Almost similar in length when the 2 piece handlepost is at its shortest.

Of course, the Fnhon handlepost is not perfect. There are some blemishes which can be seen, such as this.

Big burrs on the inside of the handlepost, at the T-shaped area. Does not affect function though.

Installing the handlepost is quite straightforward. Due to the open clamp design of the Dahon handlepost, the current bullhorn bar can be easily removed from the handlepost. Also, since the bullhorn bar already has the LitePro stem on it, it can be easily fixed onto the T-shaped end of the Fnhon handlepost. This is the reason why I chose the T-shaped handlepost for the Vitesse.

Bullhorn bar still on Dahon handlepost. The quick release lever limits the possible positions of the handlebar.

Remove the quick release clamp, and the handlebar can be removed easily!

Place the bullhorn bar to the side for now, and proceed to remove the handlepost from the bike. For more detailed instructions you can refer to the step by step guide here.

Next, we can install the new Fnhon handlepost. It goes on exactly the same way as the Dahon handlepost. No problems here.

Looking sleek!

 The surface of the handlepost looks really good. Can't tell if it is sandblasted and then anodised or painted.

After fixing the new Fnhon handlepost onto the bike, the handlepost is now ready to accept the handlebar!

Loosen the LitePro stem further, and remove the connecting tube in the middle. It is no longer required. Space out the clamps so that it can go onto the T-shaped handlepost.

Dab some Fiber Grip onto the contact surface with the stem to prevent unwanted rotation.

Place the LitePro stem over the handlepost, move them inwards onto the handlepost, tighten them and you are done!

Adjusting the angle of the LitePro stem. 

In this case, the stem is rotated behind the handlepost, as putting the stem at the front will make the reach too far, while putting it vertically up will set the bullhorn bar too high up. Since a bullhorn bar is used, the overall reach is still in front of the handlepost, which ensures the stability of the bike steering. It is not recommended to set the stem behind the handlepost when using a flat handlebar, as the resulting short reach will make the bike steering feel weird.

Bullhorn bar mounted on the T-shaped handlepost with a LitePro Stem

 Overall view of the Dahon Vitesse X20-TT with the new Fnhon handlepost

The Fnhon handlepost feels really stiff due to the 1 piece construction, and the removal of the height adjustment joint also means one less source of creaking. Bike fitting is maintained as the height is similar to what was used previously.

After these headset and handlepost upgrades, the Vitesse has also been thoroughly upgraded, with the only stock parts being the frame, fork, frame clamp and seat post clamp. It is almost at the level of the Dahon Boardwalk, where only the frame is stock!

I also have a handlepost upgrade for the Dahon Boardwalk...coming soon!

Wednesday, May 1, 2013

How to Install LitePro Headset for Dahon Bikes

The headset on a folding bike is rarely upgraded, as it is not considered an important part of the bike. However, the headset on a folding bike is under greater stress than conventional road bikes or even mountain bikes, due to the long handlepost fixed onto the bike. With this long handlepost, a lot of torque is exerted on the headset when the rider pulls on the handlebar. Thus it is important that the headset is regularly checked to ensure that it is turning smoothly with no excessive tightness or looseness.

I noticed that the Vitesse X20-TT has a headset that seems a bit worn out. When turning, the bearings feel notchy, and it is not possible to turn the handlebar more than 45 degrees to either side without the headset getting jammed. Riding the bike is still possible, as there is usually no need to turn the handlebar more than 30 degrees either side. However steering while pushing the bike is a problem as it can be difficult to turn the handlebar properly.

Due to this reason, I decided to change the headset for the Vitesse. Previously my Boardwalk also had its headset changed, along with the fork. The operation was done at MyBikeShop, as I did not have the proper tools or the skills to perform the change of headset. However I did learn how to change the headset by watching how it was done. Usually there is no need to change the headset unless it is really spoilt.

This time, I managed to borrow some headset tools that is required when changing the headset. These tools are pretty heavy and expensive, and they are also rarely used so there is no need to own a set of them unless you own a bike workshop. I borrowed the tools so that I can try changing the headset at home instead of bringing the bike down to the bike shop.

The new headset that I am going to install will be a LitePro headset. These headsets are specially made for Dahon bikes, as conventional headsets will not fit due to the extra large headtube on the Dahon frames. Both the steel and aluminium frames use the same headset.

LitePro headset in silver colour

Laser etched logo on the upper cover

The full set of headset parts

 This is the crown race, it sits on the steerer tube on the fork.

This is the compression ring, it sits on the top bearing, between the bearing and the upper cover. This part ensures a tight fit between the bearings and the steerer tube.

Bearing cup and sealed angular bearings. Same size for the top and bottom bearings.

 Upper cover. Provides a stable platform for the handlepost to rest on the headset.

Before installing the new headset, the current stock headset has to be removed. I feel that removing the headset from a bike is the most difficult operation of all, even harder than removing a square tapered BB from the frame.

First, mount the bike onto a workstand by the seatpost. If possible, rest the front wheel on the floor to provide more support. Next, the handlepost needs to be removed. Here is a step-by-step picture guide.

Use a M6 Allen key to loosen the clamp at the base of the handlepost.

Use a M10 Allen key to loosen and remove the compression bolt.

Compression bolt removed. Note that there is a brass shim under the compression bolt.

Lift off the handlepost, here you can see the black plastic headset upper cover. Place the handlepost + handlebar nearby on a stable platform. Take note not to overstretch the front brake cable as it is still connected.

Pull out the fork from the bottom of the headset. At this point the front wheel is still fixed onto the fork. You may find it easier to remove the front wheel when working on the fork.

There is a rubber seal resting on the crown race of the fork. Use a flat blade to remove it.

Those were the easy tasks! Now we will need to remove the bearings, bearing cups and crown race. From here on the operation will be more tricky and challenging.

Leave the fork aside for the moment, the crown race can be removed later on. Now the bearings should be removed from the bearing cups.

Use a flat blade to remove the circular spring clip that keeps the bearing cover in place.

Upon lifting the bearing cover, you will see lots of small individual ball bearings! Remove all of them using a magnet so that they don't drop all over the floor.

This is what you see when you remove all the bearings. What remains is the bearing cup.

After removing all the bearings on top, invert the bike frame and do the same for the bottom side. When all the bearings have been removed, what is remaining should only be the bearings cups in the head tube.

To remove the bearing cups, we need to use the head cup remover. This is a tool with split ends so that it will rest on the inside ledge of the bearing cups.

Universal Head Cup Remover

Split ends which will conform to different bearing cup diameters.

To remove the bottom bearing cup, insert the tool from the bottom and pull upwards.

If done correctly, the split ends will now rest on the inside of the bearing cups.

At this point, heavy knocking is needed to knock out the bearing cup. Use a mallet or hammer and knock on the top of the head cup remover. You will need a second person to help you hold the frame so that it doesn't move around. It can be rather difficult to knock out the bearing cups as they are press fitted into the frame.

Once done, flip the bike upside down and do the same for the other bearing cup.

Both bearing cups removed! Clean the inside of the headtube and apply some fresh grease.

Just for additional info, the bearing cups are press fitted into the head tube. Thus the bearing cup is designed to be slightly larger than the headtube, so that they fit snugly. The interference diameter will be around 0.1mm.

Inside diameter of headtube.

Outside diameter of LitePro bearing cup. Slight interference.

Lube the interface between the frame and the bearing cups for easier seating of the cups.

The bearing cups cannot be installed by hand, as it is too tight. A bearing cup press is required to set the cups properly. Do not knock in the cups using a hammer or other DIY tools, as it will damage the cups or frame, causing the bearings to malfunction also. You must use the bearing cup press to properly seat the bearing cups.

Bearing cup press. Yet another heavy tool.

The tool comes with a stepped block for different bearing cup diameters. Ensure that the block rests on the outside of the bearing cup.

 Bearing cup press ready to be used!

Once the block has been properly set on both the top and bottom, clamp the tool together and spin the handle on top to press both the cups into the frame. Do it slow and check to see that the cups are going in evenly. It should not be too difficult as this is a very powerful tool. For this frame, the bearing cups went in quite smoothly as the interference between the frame and cup is quite small.

Bearing cups seated properly in the frame. No gaps seen all around the edge of the cup.

Lube the bearing cups before installing the sealed bearings

Even though the bearings are sealed bearings, it is still a good idea to lube the bearing cups before placing the bearings into the cup. This improves sealing against water and also prevents creaks later on.

Now that the new bearing cups and bearings have been installed into the frame, let us come back to the fork. As the LitePro headset uses a different crown race, we will need to remove the stock crown race and install the new crown race on the steerer tube.

To remove the crown race, I will be using a crown race puller. This is a special tool that has blades which hook the crown race and pulls it out. If you can't find such a tool, you can use a flat bladed screwdriver and a mallet. But it will damage the crown race and possibly also the steerer tube.

The crown race puller. A very solid and heavy tool.

 The blades at the bottom of the tool, which will slide in under the crown race.

To use the tool, insert the entire tool over the steerer tube, and rest the blades on the bottom of the steerer tube.

Use the two knobs at the side to push in the blades, such that the blades are wedged in under the crown race. Take your time and double check to ensure that the blades are in the correct place.

Next, spin the handle at the top of the crown race puller tool. This forces the blades upwards, and hopefully the crown race is pulled off as shown!

The LitePro crown race uses a split ring design, so it is easy to fit the new crown race onto the steerer tube. 

Lube all contact areas on the crown race before seating it properly. This crown race will be in contact with the lower bearings.

Finally, insert the steerer tube back through the frame. Remember to put the compression ring on top of the top bearing, and cover the headset with the upper cover provided. Reinstall the handlepost and your headset upgrade is complete!

 View of the headset BEFORE the upgrade. Note the small gap at the bottom of the headset.

After installing the LitePro headset. Since there is no rubber seal ring, the gap appears to be bigger, and is a potential problem if water gets into the headset.

To solve that problem, a Lizardskin Headset Cover is used to wrap around the opening and reduce the chance of water getting into the headset bearings.

After this upgrade, the headset feels brand new again! The steering is smooth and consistent, with no notchy or friction feeling. One downside of this LitePro headset is that no rubber seal is provided to seal the bottom of the headset against water ingress. From what I know, newer versions of the headset come with a rubber ring on the upper cover to protect against water.

Overall, it was quite a tough job as it involved a lot of knocking and handling heavy tools. If there is a need to change the headset, it is recommended that you leave the job to the bike shop, where they should have the proper tools and skills to service the headset. Another advantage of changing to this LitePro headset is that in the future, if the sealed bearings need replacement, it will be just a 15 minute job, as you only need to remove the handlepost, pull out the fork, replace the sealed bearings and assemble everything back again. No need to replace the bearing cups or crown race unless those are the parts that are spoilt.