jethro00

I have not been able to squeeze out the time to coordinate with my LBS, so I plan on joining the chain gang. Alan F, I reread your instructions and they are so detailed, it would be a shame to not give them a go. Chain tools look inexpensive enough. Can anyone recommend a particular chain tool? Also, any suggestions for a degreaser? Many thanks.

Looking at:
Oumers Bike Link Plier+Chain Breaker Splitter+6 Pairs Bicycle Missing Link, Chain Plier Quick Link Opener Remover Plier for 6/7/8/9/10 Speed Chains Repair | Professional Bike Chain Repair Tool Kit

https://www.amazon.com/Oumers-Breake...s%2C290&sr=8-7

jethro00

<<Your da Vinci has three chains, two timing chains and a drive chain. You can get those already sized to length from Todd at da Vinci. >>
Joint Venture, thanks for pointing this out. For some reason, I was not seeing a link for that on the daVinci web site. I ordered a set of 3 chains from Todd today. I also ordered a chain tool, chain brush, degreaser, and lubricant today. It looks like my bike maintenance repertoire is getting ready to expand. Thank goodness I got that bike stand

jethro00

Thanks to all for the replies. I bought chain pliers, chain brushes, degreaser, and oil, and the 3 chains from Todd at DaVinci. I printed out Alan F's step-by-step instructions. The 2 timing chains did not come connected. At first, I was disappointed about that, since they can be removed and installed intact by loosening the eccentrics. But, it worked to my advantage. I used those 2 chains to learn how to use the chain pliers with the chains on the work bench. I had to take a break and watch a YouTube video to learn how to use the pliers. But, once I got the 2 timing chains linked, it was a snap to link the drive chain. I did get a second pair of hands to hold the ends of the drive chain while I used the pliers to make the link. Now that I have a chain gauge and know to check for stretch periodically, I will definitely replace why own chains when needed going forward.

The suggestions about using degreaser on a new chain and chain pliers were good suggestions. The new chains were sticky. The degreaser took care of that. The pliers really help and don't cost much.

As to the "riding buddy who can only count to 9 and a half now because he got a finger caught in the chain of his fixie while working on it," I am pleased to report that all 10 of my fingers (and tips) are present and accounted for.

jethro00

Today was our first attempt to ride the Grand Junction after changing the 2 timing chains and drive chain and right grip shifter. Everything looked and sounded fine turning the pedals on the stand. But, as soon as we mounted to ride and pushed on the pedals, the chain slipped on the front chain ring. Then, it stopped slipping and made a grinding noise at the front chain ring like it somehow is not lined up correctly on the front chain ring. But, it looks fine and the chain looks tight. We could not ride it. When we got off and spun the pedals, it's fine. When we tried to mount and ride again, the same thing happened. Is there any explanation other than the front chain ring (4 years old and in use every day) needs to be replaced? If the front chain ring needs replacing, how hard is that to do?

unikid

This video should give you some ideas. Although this is for a single bike, the front of a tandem should be the same if not easier, once you've loosened the chain.

Joint Venture

Disregard the above as it doesn’t apply. On a da Vinci tandem, the chainrings are hyperglide cogs mounted to an intermediate shaft with the double block freewheel on the other end, which forms the heart of the Independent Coasting System. The cranksets have only the timing rings on them.

There are instructions for removing the intermediate shaft in the Owner’s Manual section of their website:

https://www.davincitandems.com/owners...mediate-shaft/

I’ve done it both with and without the special tool. It’s not hard.

jethro00

Joint venture,

Thanks for the link. I will ponder whether to give it a go or check with LBS on this.
Either way, I will order parts. I see:
Chainrings for da Vinci Tandem: 12, 18, 24, 30 tooth $58
Chainrings for da Vinci Tandem: 12, 18, 24, 30t with conical spacers $92
Double Freewheel Block (DFB) Tool $25
I think I will get the tool, even if I take it to the LBS.
Do I need the conical spacers or can the current ones be re-used?
Am I correct that you get a set of chainrings for the listed price?

Thanks.

Joint Venture

If those are the chainrings you have currently (4-speed front shifting) and they have the conical spacers (which act as shifting ramps), then order just the quad rings set (yes, that’s a set they’re selling) as the spacers can be reused. If you have 3-speed front shifting, then order the set of triple rings they offer, instead of the quad. If you have something custom, call Todd directly to order or source individual cogs yourself.

Most LBS have never worked on the da Vinci ICS, so it’s a good idea to become your own expert, unless they have. Good luck and have fun!!

jethro00

Joint Venture,

I am working on becoming my own expert. Replacing the 3 chains and right grip shifter are progress. Thanks to you and everyone else who has replied with the info I need to learn how to work on our tandem. Since we ride every day, we keep our Trek T900 as a backup on those days when I am going through the learning curve working on the Grand Junction.

We have 3-speed shifting. So, it looks like item #: CG. 13, 21, 28 tooth is the right set. I emailed Todd at DaVinci to make sure.

jethro00

Good thing I checked with Todd at DaVinci before ordering. Todd says I need the 14, 21, 28 tooth set, which is not listed in their online components. Todd says he will send me the ones I need for the Grand Junction.

Joint Venture

Todd is a great resource for product support. I’ve spoken with and e-mailed him many times over the years. Great product and great guy!

jethro00

I've looked at the instructions for removing the intermediate shaft in the Owner’s Manual section of DaVinci's website:
https://www.davincitandems.com/owners...mediate-shaft/

At this point I am just replacing the front chainring. Alas, Todd sent me what Joint Venture was referencing, 3 chainrings that go on the intermediate shaft. I thought the front chainring was part of the chainring set that I was getting. How do I identify the front chainring that goes on the captain's cranks and holds the front part of the timing chain? I think that is where the problem lies.

Joint Venture

What you are referencing are commonly called “timing rings” in the tandem world. On a da Vinci tandem, the front/rear timing rings are the same as most conventional tandems and attach to the left side of the captain/stoker cranks. On a conventional tandem, these timing rings would be joined together by one long timing chain, but with ICS there are two timing chains (one for each crankset) and they each drive the double freewheel block on the intermediate shaft, which in turn drives the cogs that serve as chainrings, which are connected to the rear hub cassette cogs via the drive chain.

Replacing your timing rings is a matter of figuring out the BCD (bolt circle diameter) of those rings, 110mm is common, and replacing the rings (I suggest in pairs). There is nothing special or proprietary about these “chainrings,” on a da Vinci Grand Junction model. Just get ones that fit your cranks and make sure they are the same size front/rear. Stick with the same tooth count as the old “chainrings” when purchasing new ones to serve as your timing rings or else you’ll alter the gearing of your da Vinci, due to the ICS! Note: since timing rings don’t shift, they don’t need to be ramped and pinned, so you can get by with inexpensive chainrings for that application!

jethro00

It looks like the timing chain rings are sometimes referred to as "spider" rings.
On our GJ they are both etched with PE 110-34.
The ring on the captain's cranks is also etched KS H06.
The ring on the captain's cranks is also etched KS I01.
I can't figure out what KS H06 and KS I01 refer to.
The only replacement I see is Surly Stainless Steel Chainring
Silver, 110mm, 34 Tooth, 5 Bolt
ITEM # CG408A26.
This chainring is ideal for single-speed, fixed gear or tandem timing chain applications. It is not ramped or pinned for shifting assistance, so shifting will be a bit slower if using these with a front derailleur. NOTE: (all) 94mm BCD, (all) 104mm BCD, and 110mm BCD x 34/35/36t chainrings are made with a 2.2-2.3mm thick stock plate and they work best with 5- to 8-speed chains. The 110mm BCD 38-50t and all 130mm BCD chainrings are machine finished to have a 2.1mm tooth thickness and will work fine with 9-speed chains.

Our GJ has a 9-speed grip shifter.
So, it looks like it should fit.

Joint Venture

Spider refers to the arms, usually 4 or 5, to which the chainrings attach. Some cranks have spiders which can be changed out, but most are fixed. I saw a pic of a Grand Junction on eBay and it appears to have cranks with 5-arm 110mm BCD for the timing chainrings. You should be able to get 34t rings much cheaper than your link - probably half that cost or less. Check online.

UPDATE: My bad, when I went to your link, the price was $70 for the default. But when I noticed it was not for 34t 110BCD 5-bolt rings, I found that when I changed the selection to what you need, the price was only $35 each. Not cheap, but stainless steel should last MANY times longer than aluminum and you’ll likely never notice the slight increase in weight!

jethro00

Well, my stoker voted that we take the Grand junction to the LBS for diagnosis before buying new spider rings. We dropped it off late last week, but it has still not been evaluated. The LBS is swamped with bikes being dropped off for repair. So, we picked the bike up today and ordered 2 Surly Stainless Steel Chainring, Silver, 110mm, 34 Tooth, 5 Bolt, ITEM # CG408A26. I will replace the timing chainrings and see if that solves the problem.