Monday, October 28, 2013

Avanti Inc 3: Special Crankset Setup

After I got my new Avanti Inc 3 a few weeks ago, I have been preparing it for proper service. It is not that easy to get it ready, as it is not a normal bike. This was not helped by the fact that the internal hub gears were not adjusted properly. All the adjustments and crankset installations described below are done over several days as it is very time and energy consuming.

When I was testing the new bike after delivery, I found that there were only 10 selectable gears, instead of the 11 gears in the Alfine 11. I found that the shifter inner cable was not connected properly at the internal hub end, which caused one gear to be lost. Normally the internal hub gear indexing is done at gear 6 for Alfine 11, by ensuring that the yellow lines are aligned. However, I found that the yellow lines actually match up at gear 5! This means that the initial setting wasn't done properly. Re-adjusting the inner cable took a bit of time, but it was eventually set up properly at gear 6.

Yellow lines match at gear 6! For Alfine 11, this means that the gear indexing has been done correctly.

There was also an intermittent creaking of the bike whenever I pushed hard on the pedals. This could be due to many reasons. It could be the pedals itself, the pedal threads, the chainring bolts, the crankarm attachment to the BB, the BB in the eccentric BB unit, the eccentric BB in the frame bottom bracket shell, and so on. It was only solved after much tweaking, which will be described in the next blog post.

One thing which I didn't like about the bike was the crankset. The FSA Vero crankset looks pretty decent, but it is actually quite flexible under load. I found that just by stepping on the pedal when the crankarm is at the 6 o'clock position, I could feel the crankarm bending inwards. This was not acceptable for me, so I decided to get a better crankset for the bike.

The best crankset to match the Alfine 11 internal hub is of course the Alfine crankset. It is a single chainring Hollowtech II crankset, using the Hollowtech II BB. This system will definitely be stiffer than the ISIS system used by the FSA Vero (at least it wasn't using square taper BB).

New Alfine crankset!

Black colour spec with 45T chainring. I will actually only require the crankarms as I am using the Gates belt drive front pulley.

Removing the existing crankarms and pedals are always a pain, and those who do their own bike maintenance will know how troublesome it is. The pedals came off rather easily, which was quite surprising. Next, the crankarms came off only with much effort, even though I used the proper crankarm extractor tool to pry the crankarms off the BB spindle.

After that, the ISIS BB itself needs to be removed from the eccentric BB. This required the BB tool plus a long leverage pipe to remove the BB. Again, it took quite a bit of effort to get it off.

Once the FSA Vero crankset has been removed, I removed the Gates front pulley from the FSA Vero crankset, and installed it on the Alfine crankset. This is again troublesome as it means removing 10 chainring bolts that are stubbornly stuck on both the crankarms.


Sorry that I don't have any pictures of all these, as my hands were pretty much covered in grease throughout these operations.

Next, the Hollowtech II BB (105 BB from previous crankset) was installed onto the bike. I had initially planned to extract the eccentric BB from the frame to take a look, but it was stuck really tightly. The pin spanner that I had got to turn the eccentric BB did not fit at all, thus it could not be used.

Pin spanner for adjustment of eccentric BB

The two pins are supposed to go into 2 holes on the eccentric BB, allowing you to rotate the eccentric BB in the frame. But it does not fit anywhere and cannot be used at all.

Finally, I could install the Alfine crankset! However, as soon as I put the crankset spindle through the BB, I realised that I had a big problem. The other end of the spindle that sticks out from the left side was too short! There was no way I could tighten the left crankarm onto the short length of spindle that was sticking out. I could not even screw in the left hand crank cap as it was too far out to engage the thread in the spindle.

After some investigation, I found that the BB shell width on the Avanti (eccentric BB) was 73mm! I had assumed that it was 68mm, since it came with a 5-arm crankset which is typical for a road crankset. Road cranksets normally use a standard 68mm bottom bracket width, which would have accepted the Alfine crankset without any problems. This meant that I was 5mm short in spindle length.

At this point, I was stuck. There was no way I could continue to use the Alfine crankset as the spindle is too short. No way to fit a crankset meant for a 68mm BB width onto a BB of 73mm width. I had two options: To reinstall the FSA Vero crankset, or to get a MTB crankset (with longer spindle). Using a MTB crankset would require getting a 4-arm Gates front pulley, which adds on to the cost. I decided to put everything on hold and think about it.

The graphics below show the approximate measurements for a few crankset and BB setups. It will help you to understand the differences and how I eventually managed to solve the issue.

1) Standard Road Double Crankset in Standard 68mm BB Shell Width


This is the ideal setup, with a standard BB shell width of 68mm for road, and the usage of a road double crankset. The spindle length of a road double crankset is about 110mm. This leaves about 20mm of protrusion at the left side for the fixing of the left side crankarm. This would have been the ideal case if the Alfine crankset was installed into a BB width of 68mm.

2) Alfine Crankset in 73mm BB Shell Width


This turned out to be the actual case for the Avanti Inc 3. I attempted to fit a 110mm spindle through a 73mm BB shell, which gave me only 15mm remaining at the left side. This was due to the BB shell which was 5mm wider (73mm vs 68mm).

Through some research, I found that the difference between a road Hollowtech II BB and a MTB Hollowtech II BB is actually the width of the BB cups. The MTB BB cups are actually about 1mm narrower on each side! I also knew that a road triple crankset has a longer spindle, to accomodate the larger chainline required for a triple chainring setup. I realised that by combining these two features, I could actually make it work!

2) Road Triple Crankset with MTB BB in 73mm BB Shell Width


This was the final solution which I thought of. I found a road triple crankset, and measured the spindle length to be 112.5mm, which is 2.5mm longer than the road double or Alfine crankset. I also used a MTB BB, which have BB cups of 10mm wide on each side, instead of the 11mm of a road BB. Together, I managed to get an extra 2.5+1+1 = 4.5mm of spindle length on the left side! This is almost the same as the required 20mm, which means that I did not have to reinstall the FSA crankset or to use a MTB crankset (which will greatly affect the chainline).

Difficult to see, but the road BB cup on the left is about 1mm wider than the MTB BB cup on the right.
 
Using the MTB BB, together with the road triple crankset, there is sufficient spindle length on the left side for proper fixing of the left crankarm.

Final setup with a Sora triple crankarm, Gates front pulley and Shimano PD-A530 pedals.

For optimum chainline, the front pulley needs to be installed on the inside of the crankarms.

At this point, the crankarm has finally been installed successfully, but other problems have surfaced. Somehow the belt tension has decreased after I removed and installed the new crankset. Also, the creaking sound is still present. Seems that I have no choice but to try adjusting the eccentric BB, both to increase the belt tension and to also eliminate the creaking sound. This will be continued in the next blog post!

Extra Info: Standard MTB Triple Crankset with MTB BB in a Standard MTB 73mm BB Shell Width


A MTB crankset spindle is much longer than a road crankset, to allow it to pass through the wider BB shell, and also to have a more secure attachment to the left crankarm (24mm, more than 20mm for road).

Note that all these length and width measurements are approximate measurements and calculations, and are not official design dimensions. They may vary from my calculations.

19 comments:

  1. This sounds a bit concerning. I have an Inc 3 2014 on order and I thought the crank arms didn't look too heavy duty on the Inc 2 they had on the floor. For the asking price one would expect it to have top quality componets. I hope the crankset is satisfactory or I'll be pretty pissed off.

    Well done for improving the bits you could anyway, I know I'd succeed in fudging it up beyond repair if I tried tinkering.

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    1. The crankset is OK, its just that I am a bit fussy.

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    2. Sure. though I'd say anyone who coughs up for the top spec Inc would be fussy. I'm guessing you'd way a few less KGs than me too since you have the small frame Inc. I'm 80kg's on a large so it could be interesting.

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    3. I weight around 65kg, and my height places me right between small and medium sizes, according to the frame size guide on the Avanti website.

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  2. Thanks for publishing your findings. Agree that the FSA Vero crank is quite flexible. I'm swapping for Shimano 105 - model FC-5703-L and bottom bracket SM-BB5700. The missing piece of the puzzle is a Bushnell Featherweight eccentric and 55mm shim. This will get you around the 73mm issue. The BB shell on the Inc 3 is 66mm which appears to be the industry standard. For some strange reason Avanti have used an eccentric that has 'extensions' / 'extrusions' to take the width out to 73mm where the BB threads in. You can see these in your photos. By swapping the Avanti eccentric for a 66mm eccentric that accepts a 68mm BB (English Thread required not Italian Thread) you can use a triple ring 105 set with matching BB and mount the Gates ring in the middle ring position for a nice straight chain line of 45mm. Specifications on the Alfine 11 rear hub say it has a chain line of 41.8mm, but my measurements on the Inc3 show 44.5mm so this should be a great match for the 105 middle ring position.

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    1. Thanks for sharing the info! It is so good to hear from someone who knows about these eccentric BBs. Yes I wonder why a 73mm eccentric BB was used.

      Great to hear about the chainline measurements. However, I am in the process of getting a new front chainring! I find that the entire gear range of the Alfine 11 is too high for me, and I only use the gears 1-8, making it an "Alfine 8" instead.

      The smaller 42T chainring will be of the 4 arm type, with 104 BCD. This means using a MTB crankset instead. This will solve the problem of the 73mm BB and also the short spindle issue.

      I also forsee that the chainline will be moved outwards due to the MTB crankset, and I have sourced for longer chainring bolts with spacers to adjust the chainline. Will update once I figure everything out!

      Do share how the upgrade on your side is going!

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    2. One question I have about the Bushnell BB with the 55mm shim: What is the current BB shell diameter on the Avanti? Is there a need for a shim, or will it fit without the shim?

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  3. My measurement of the Avanti eccentric shell inner diameter is 55mm, but the Bushnell is made for 53.8mm to 54mm. They make a shim (sleeve) for 55mm and also 57mm which appear to be the other common dimension eccentric shells. I've ordered the parts and they should be in the mail now. I'll let you know how it turns out. I'd prefer not having to use a shim, less parts is always best, particularly for creaks etc, but I'll grease it up and see how I go. Really looking forward to getting rid of the FSA cranks. I considered the MTB 4 arm crank option also and will be interested to see how your's turns out. The spacers should get the chainline where you need it. I was wondering how to fix that problem. The Gates website had a lot of options for front and rear CDX sprockets and belts. You should be able to tune your ride just how you like it. Do you need to get a shorter belt?

    ReplyDelete
    Replies
    1. Thanks for the valuable info about the eccentric BB, this will come in useful should I ever need to replace the eccentric BB.

      I just received the last piece of the puzzle, which is the 42T chainring today. Will fix it up this weekend and see how it goes. Yes I will be putting on a new 113T belt for the smaller chainring.

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  4. Hi, I have an inc 3 and have a question about the FSA Powerdrive BB. Mine is clicking a bit and I think needs changing, the bike is pretty new so may be a duff one? anyway, I'm not sure if it's a standard ISIS fit and so I can get an FSA platinum instead or if it's something different and I can only get an identical replacement to fit the cranks. Lastly, what length should I buy? 68 or 73, 113 or 118 or whatever? Appreciate any advice.

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    Replies
    1. It is an ISIS mounting, so any ISIS BB will be OK. It should be a 73mm width. You can check the specs when you remove the BB from the frame.

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  5. I have an inc2, looking to replace the cranks at some stage, from this writeup and the images I take ti the Shimano Soma and alpine are the same thing?

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    1. They have similar dimensions. The main difference is that the Sora has a double chainring while the Alfine has a single chainring.

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    2. thanks, though yours are a single? and have sora printed on them and arrived in an alfine (computer is determined to correct that to alpine) box???

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    3. I first tried an Alfine crankset which didn't work, I then tried the Sora triple crankset which worked.

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  6. Hi Steve,

    I own a Carbon Drive Tikit and would like to change the Crank to Shimano 105 crank. One of the bike shops i went to suggested that in order to use the 105 crank, they would need to put spacers to align the belt drive.

    currently my bb is a 111.5mm BF Sealed 68xEnglish.

    Do you think there will be any issues?

    Thanks!

    -HB

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  7. The bike shop is right in that spacers might be needed to offset the Gates front pulley to suit the rear pulley chainline. If you change to the 105 crankset, you will also need to change the BB.

    The only issue might be that you will need the appropriate spacers and longer chainring bolts for this modification. Do check with the bike shop to see if they have these parts before starting the modification.

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    Replies
    1. Hey man!

      Thanks for your reply and advice!

      So the model i should get is
      Shimano 105 5700
      52.39t
      130mm bolt circle?

      Yea they have the BB. I would need to check if they have the spacers and longer chainring bolts.

      -HB

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    2. Yes that would be correct. Just make sure your current front pulley can be fitted on the new crankset.

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