DubT

If I remember how to do it here are pictures of the new cranks.

One thing that is really good about the new cranks is that the front "Q" factor has been reduced by around 18mm, the rear is reduced by about 3mm. The chain line is right at 51/52mm.

waynesulak

The cranks look good on your (very clean) bike. I hope Shimano keeps making tandem cranks.

Wayne

DubT

Wayne, these are the brand new ones that they just released, according to the tech guy they have been developing them for some time.

M.Salvador

could you describe the attachment method of the left rear crankset? thankyou!

DubT

The axle is splined as is the crankarm, external/internal and held on with a fixing bolt.

Here is a link to the Shimano tech document that shows how everything is assembled. https://techdocs.shimano.com/media/te...9830753886.pdf

Wayne

teamdonterri

I like the gray as opposed to the bare aluminum finish, and hope they don't scuff like our XT and XTR mtb cranks did...Very sharp with the white frame!

Chris_W

Thanks for the good quality photos and actual specs. This is very useful info.

It looks like there is lots of room behind the timing crank-arms to mount a belt-ring with a couple of spacers between it and the mounting tabs. We could then obtain the couple extra mm's we would need to make the ring clear the chainstays.

Now I just have to find out if the 170mm captain cranks are actually going to be available to buy, and decide if I can put up with the idea of losing the ability to easily change chainring sizes (this being the other big drawback of this crankset for me).

DubT

Can you tell me why you are going to use a belt drive? If I ever use one it will be the CDX (if they release it for tandem use) that uses narrower rings and a new design that will tolerate misallignment and keep it on the rings.

Wayne

jnbrown

Very nice. Is it possible to change the inner ring to a 28T?

Chris_W

Because we've been using it for the past 7,000 kms with minimal problems and are very happy with the setup. The positives outweigh the negatives for us, which I've discussed in other more relevant threads.

DubT

I do not know, a call to Shimano Tech should answer your question.

Wayne

Chris_W

Not easily; only if you also change the middle chainring.

The inner ring is bolted to the middle with an unusual 92mm BCD. To change the inner ring, you need to get a "Tripleizer" middle ring, with 130mm to 74mm BCDs. Stronglight and TA Specialites both used to make them, but I believe only one of those is currently available, but I can't remember from which company. Shimano has used this design on the more recent Dura Ace triple cranksets (models 7703 & 7803), and the current Ultegra triple (6703), which this tandem crank is based on.

I am wondering if anyone else thinks that not having dedicated mounting posts for the inner ring would reduce the stiffness, which could be a problem when a tandem team is climbing a steep hill? Will the problem be increased if using a tripleizer with a 74 mm BCD inner ring instead of Shimano's special middle ring with the slightly larger 92mm BCD? Or, should I not be worrying about this?

waynesulak

Good point. That is why I will stick with Square taper and Davinci cranks. Custom lengths front and back and custom Chainrings of any brand. Standard BCD including 74 granny. I have nothing against recent crank "standards" but I see no advantage that is worth giving up good fitting crank lengths and custom gear ratios.

In a perfect world a BB30 bottom bracket with lots of crank lengths and standard BCD is my choice.

Wayne

twocicle

I was looking at your photos to evaluate how you appear have installed a N-Gear Jump Stop chain guide on this Calfee. From my initial stab at doing the same, the mounting strap won't go low enough on the seatpost (due to the BB junction taper) to clear the front derailleur.

Did you run into the same problem and resorted to raising your derailleur 1/4" or so (seems higher than normal) to clear the Jump Stop?

JSNYC

putting on my n-gear thingie was a nightmare. have similarly tapered bb junction with a huge seat tube. here's what i ended up doing: took the crank off, heated the strap for about a minute in boiling water, then scrambled while it was still warm to pinch it enough with channel locks (covered in a rag, didn't want to scratch paint if slipped!) to get the bolt to grab the nut threads (of which there were precious few given the tube taper, i.e., the clamp was so far spread out).

it took me several tries to get it on, but i did. invented some new curse words along the way as well...

DubT

It took some careful fitting and you see the result, the derailleur is higher than normal but works GREAT!

Wayne

Chris_W

I'm still considering getting some of these cranks for us, especially now that we're going with a Rohloff hub and so don't need the inner ring. Chainline is important for the Rohloff, so can you just confirm how you measured the chainline: you said that it is 51/52 mm, I assume that this is measured from the center of the seat tube to the center of the middle ring, is that correct?

DubT

Chris, I just remeasured the chain line and the dimension from the edge of the boom tube to the C/L of the chain is right at 24 mm. That is a little bit easier to measure than the center of the boom tube.

Wayne

jfarwell

great looking bike. Plan to get a similar one soon. Did you look into Di2 shifting?

twocicle

With a .6mm + .1mm spacer on the drive side, my "edge of the boom tube to the C/L of the chain" is 21mm. From center of boom tube = approx 47mm.

DubT

I do not remember installing a spacer on the RH drive side of the rear cranks. Here are the instructions and I do not see a spacer on that side.
https://techdocs.shimano.com/media/te...9830753886.pdf

Waynd

DubT

Thanks!

I did not consider Di2 for several reasons:

I still want a triple for emergencies, we rarely use the middle ring let along the small ring but we had to use it a couple of times.

I like close spaced gears.

I am very happy with the way the bike shifts.

I do not want to have to mess with batteries/wiring etc in the drive train.

The mechanical is less expensive and I can fix/adjust it.

Looking forward to seeing your new ride!

Wayne

twocicle

Go find the exploaded parts doc: EV-FC-R603-3246_v1_m56577569830763644.pdf (sorry I don't have the link handy). You will see Item No. 12 Y1F913000 Spacer (6.5 mm) on the drive side.

Yesterday during my install process I called Shimano tech support to inquire about some of these points since there is some discrepancy between the install doc and the tech blowout doc.

Basically, the first thing you're suppose to do immediately after installing the BBs, is to figure out the minimum number of spacers needed. Then it's up to you which side you install the spacers on, as long as you use the same total value.

Since I wanted near identical front-rear timing alignment, I adjusted to use .7mm of spacers on the drive side, leaving only the single spacer with the built-in rubber ring/washer on the timing side.

The other trick to timing alignment is to add some washers on the timing bolts between the spider and the rings.

I'm learning as I'm going here, so anyone that knows what they're doing feel free to correct me or suggest a better approach. Thanks.

DubT

Here is the URL: https://techdocs.shimano.com/media/te...9830763644.pdf

Very interesting, I still do not remember that spacer. My crankset is an early unit, I bought it from the rep, it was his demo unit. Maybe they made some changes, mine fits great and works great.

twocicle

Well, another important consideration I forgot to mention is that both cranks are the same distance from the centerline. ie symmetric. Not sure why when I added .7mm to the drive side, my 21mm measurement from the boom tube edge is less than your measurement without any spacers in your setup on the drive side. Strange. We both have 68mm BBs.