Tandem Cycling - Lightning Crank Question

Swapping notes with Lightning about their cranks, but responses from them are terse. They seem to think setup with a double and Gates belt all on the right better than the more conventional setup with the Gates belt on the left. Assuming you are OK with a double, what are the pros/cons to running the timing belt on the same side as the rest of the drivetrain?

Pretty much the same as same-side drive

Pro #1: Less wear and tear on the rear bottom bracket.
Pro #2: Ever so slight, somewhat more efficient transfer of power
Pro/Con: Eye catching look that draws attention
Con #1: You typically give up the triple / granny gear
Con #2: Over-shifts into the right side, rear timing ring/pulley can be ugly
Con #3: Right side pulley may need to go outboard (big ring position) due to it's size

Con #2: Over-shifts into the right side, rear timing ring/pulley can be ugly
Con #3: Right side pulley may need to go outboard (big ring position) due to it's size

With the Gates system, I'm thinking an overshift might equal a new belt. If you torqued the belt, or nicked it up, I'm not sure I'd keep riding with it.

As for No 3, fiting the Gates ring would seem to be rather problematic as you allude to. It's substantially wider than a conventional chainring. I'm thinking on many frames, if you put the timing ring on the inside, and moved the crank far enough right to clear the stays, you'd have a chain line issue.

http://i72.photobucket.com/albums/i165/bobstewart/carbontimingbeltclearance.jpg

Mburchard,

If you don't mind saying, what price are they quoting you for both cranks?

Mburchard,

If you don't mind saying, what price are they quoting you for both cranks?

Haven't asked yet. Want to figure out what I want, then will ask how much. Have Santana carbon cranks on DA Octalink BBs now, will also want to understand weight delta.

I'll have a tandem set of Lightning cranks in route. Fedex will deliver them Friday. I'll get total weights when they are here.

One of the nice things about Lightning is that you get to communicate with the owner of the company, and the inventor (http://www.google.com/patents?vid=USPAT6443033) of the crank, Tim Brummer.

The sync side spyder on the Lightning crank doesn't create sufficient clearance for the wider Gates belt/ring, and thus needs to be reversed to clear the chainstay. It works fine, but doesn't look very good. Tim has told me that he will make a new spyder when he gets a CNC Machine (http://www.sheldonbrown.com/dp-forging.html).

This spyder problem is obviated by having all the rings on the drive side, and this I think is the origination for Tim's preference for the belt on the drive side. I think that if Lightning had a sync spyder that fit a Gates on the non-drive side, you'd not be hearing so much about having it on the drive side.

This is the tandem Calfee exhibited at the Northwest Tandem Rally with a drive-side sync Lightning, only with a chain rather than belt.

http://img28.imageshack.us/img28/2259/drivesync.jpg (http://img28.imageshack.us/i/drivesync.jpg/)


http://img443.imageshack.us/img443/8674/drivesync2.jpg (http://img443.imageshack.us/i/drivesync2.jpg/)

This bike is awesome. Couldn't stay away from it at the ralley. A claimed 22lbs as it sits. I'm saving $$$$$.

A claimed 22lbs as it sits.

Scale shots are very useful in this regard.

http://img199.imageshack.us/img199/8272/2195s.jpg (http://img199.imageshack.us/i/2195s.jpg/)

Dripping with excitement. Replacing the rim brake with a disc seems likely in my neighborhood. Throw a Scrub rotor on there and the weight won't seem so bad, and will look very trick, along with the rest of the bike. It looks fast sitting there. N+1

I'm not seeing an inner of the double chainrings on that Calfee. It looks like it just has a 50t ring and a wide ratio rear cassette. Are the pictures misleading, or is it set up for riding in Florida / the Netherlands only?

I'm not seeing an inner of the double chainrings on that Calfee. It looks like it just has a 50t ring and a wide ratio rear cassette. Are the pictures misleading, or is it set up for riding in Florida / the Netherlands only?

I saw the same thing but dismissed it under the heading of 'who really cares'. My guess was, it was left off to garner a few less grams for the "ooooh" factor of the bike show. In fact, I was surprised that the front derailleur was left on, even if only used as a chain guide to keep it from droping into and locking up the sync chain.

Neat bike, and the weight is obviously impressive. But, IMHO, you've got to question the gearing tradeoff. To make up for the triple you're forgoing, they appear to be using an XX rear cassette that in addition to costing $328, give you the following spacing:

either 11,12,14, 16, 18, 20, 22, 25, 28, 32.

or 11, 12,14, 16, 18, 21, 24, 28, 32, 36.

Those are fairly big jumps.

If you need low gearing I'm thinking most teams would be better served with a triple, better spacing, better shifting, albeit at a bit of a weight cost.

It has an 11-36 with a compac crankset

^ which is going to give a very low gear and a wide range, but big jumps.

In spite of my post above, I'm intrigued by the setup for our use. We'd be fine with a 50/34, and an 11/23 in the back for 95% of our riding.

And for the other 5%, put on a larger rear cassette, and accept the spacing tradeoff.

I'm not seeing an inner of the double chainrings on that Calfee. It looks like it just has a 50t ring and a wide ratio rear cassette. Are the pictures misleading, or is it set up for riding in Florida / the Netherlands only?

I emailed Mike Moore at Calfee to inquire about the missing inner ring. He sent me some more pics, and lo, there is an inner ring.


Hi Ritterview,

We have a compact set-up with 2 rings (34/50) and then a pair of 34t timing rings. The visual symmetry of the rings is quite nice and might explain the errant diagnosis. It works swimmingly and I've already sold this exact configuration, on Dragonfly frames, no less than 4 times these last couple of months.

Here are some photos illustrating our drive-train. We also weighed the bike with 25c tires, among other "tandem-ready" specifications.


http://farm5.static.flickr.com/4123/4813121998_65a133344f.jpg

http://farm5.static.flickr.com/4078/4813122396_46e2410540.jpg

http://farm5.static.flickr.com/4137/4813122528_c36fdc44d9.jpg

Pretty slick. I retract my earlier "who really cares".

That said, I'm not thrilled with the aesthetics of the out-board, same side drive, but that's just me.

I swear I've typed this out. I must keep forgetting hit submit..

Mine arrived. 1091grams is the weight of everything but rings. It is a traditional setup with the Gates drive belt on the left and triple on the right.

With the roads around here, we're going to just run a double with a 38/53 or a 54 and an 11-28 rear. With 11-25 in the rear, we rarely put it in the middle ring. With the 11-28, I doubt we would except for our cadence drills we do.

+1 about talking with Tim at Lightning, there's no doubt that he's an engineer. Nice guy, knowledgeable and delivered exactly in his time frame promised. (1 month) Which isn't bad considering the Tandem setup is custom.

Has anyone done something similar to the Lightning crank setup by using a triple crank for the stoker and a compact crank for the captain. The triple crank could be 52/38/36, and the compact crank would have just a 36t on the inside. The one issue with this is finding a 36t x 74mm chainring for the triple. I did find one made by Stronglight in France.

It seems that this would yield a better chainline since the cassette is already pushed out by 5mm or more with 145 spacing. Also, you could use a variety of different crank manufacturers.

One concern would be no granny gear, but we currently ride a 52/42/30 with an 11-28 cassette, and we rarely want to use the 30, so by going to a 38 we don't think we would have any issues.

If someone has tried this, can you post pictures?

Scale shots are very useful in this regard.

http://img199.imageshack.us/img199/8272/2195s.jpg (http://img199.imageshack.us/i/2195s.jpg/)

Impressive weight. But you cannot ride a bike without pedals.

Impressive weight. But you cannot ride a bike without pedals.

Well, its not my bike, so I won't be riding it anyway. But since pedal weight is so variable and individual, and the bike is often sold without pedals, comparative weights more often than not are sans pedals.

Well, its not my bike, so I won't be riding it anyway. But since pedal weight is so variable and individual, and the bike is often sold without pedals, comparative weights more often than not are sans pedals.

I know, you're right. Just one of things :-)