jacks1071

Is there any reason why we shouldn't run a Track/BMX chain as our timing chain?

My bike came with a 10sp chain as the timing chain - its holding up so far.

I have snapped the drive chain which was a YBN chain that came on the bike - I re-joined it and hoped it was a once off event as this happened on my first ride, then it broke again on the 3rd ride. YBN drive chain is in the bin and a new Ultegra 6701 chain is on there now - we went into the hills tonight and no issues. The timing chain is also a YBN 10sp which has me a little worried but so far so good.

The bike has Shimano 10sp groupset with a MTB Rear Mech and MTB 10sp cassette.

I don't mind the idea of the 10sp chain as the timing chain as it means only one type of joining link in the spares kit but I think we must loose a bit of power in chain stretch. With the bike standing still if you push on a pedal there is for sure some flex in the drive train.

I don't have much clearance on the rear chainstay but there is enough there to fit the bigger chain. Would I be advised to fit the wider track sprockets as well?

I could goto a little smaller sprocket to increase the chain stay clearance. I'm a little worried if we drop the timing chain, a WIDER chain would be more likely to get jammed in there damaging the frame whereas the 10sp chain has pleanty of clearance so it couldn't really get jammed anywhere so that is one consideration for us.

Interested to hear everyone's feedback. I've done some reading on the belt drive setup but not sure if I want to goto that sort of expense and I think I prefer the idea of a chain over a belt just from a spares availability perspective.

TandemGeek

Just about any type of a chain will work for a sync chain so long as you get pretty good engagement on the timing rings. MTB / Fixed Gear chains almost want for a matching ring, given how wide they are. 8 speed chains also work.

The only down side to having a sync chain that's a different width than your drive chain is the inability to do a field repair of your sync chain with links stolen from the drive chain. The work-around is easy; just carry a small piece of each size chain in your repair kit along with the correct size quick-links.

I'm not sure what may have caused your chain breakage issues, but I always suspect the one-time-use pins and/or a bad shift under heavy load at low RPM. If it's the former, re-useable links like a SuperLink III or the ones from KMC, Wipperman or SRAM typically solve that. I haven't used a press-in pin in a long time on a drive chain... saw way too many coming apart at those one-time-use pins.

If they're breaking while you're shifting, chances are you're waiting too long to get into an easier gear. Gotta keep the pedal revs up to achieve the best possible shifting performance with a tandem. Two people put a LOT of load on that drive chain and those chains just don't want to move off their sprockets without a fight once the revs. get down below 70 and into the 60's or 50's.

jacks1071

I always use the SRAM Powerlock ones, the bike we've got is pretty good but for some reason they used cheap chains and a cheap cassette. On the first ride the pins in the cassette failed - no problem we just use the working gears and ride home, then the chain snapped.

It is possible the chain slipped and grabbed and maybe we damaged it due to the sprocket failure. I replaced the sprocket but didn't want to throw out a brand new chain which was a mistake I won't make again...

We've learned a fair bit since the first outing. Since we put the MTB rear mech on (long cage) - it shifts heaps better under some load than with the short cage, I just back my power off a little and shift - I only tell the stroker to soft pedal for front changes.

Understand what you mean about stealing some links - I might put a bit of left over chain in my saddle bag otherwise I'll need a bag of joining links!!

If running the big single speed chain - surely as long as I keep an eye on stretch it must be nearly impossible to break?

I also like the idea of reducing power loss in the drive train through chain stretch.

TandemGeek

My experience tells me, if I have the spare parts I need for some type of failure... it never fails.

So, as improbable as a sync chain break is -- even with a heavy-duty BMX chain -- I'd rather be prepared to ward-off the gremlins.

After all, what's the likelihood that someone will have a spare "link" if it did fail? Kinda like riding a tandem with 27" tires these days.... not too darn many.

rdtompki

We've only been riding tandem for 2 years/7000 miles, but I would think most any 8 or 9 spoeed chain would work fine for timing. 9 speed is attractive for most folks since 9-spd cassette is so common. The TC is running true on the rings and I've seen no reports in either Hobbes or hereabouts regarding timeing chain failure.

Regarding calling out RD shifts it's been our experience that most of the time it's not necessary even with our ICS drive train, but I would think when climbing if you do let the revs get low before shifting and especially if you have a strong stoker, you can put a really big load on the drive train. YMMV.

waynesulak

When we purchased our Comotion Speedster in 2006 it came with a single speed timing chain. The weight weeny in me pushed me into going with a 9 speed chain when it needed replacing but the single speed worked well.

Wayne

Dean V

Stick with the 10sp timing chain. No need for anything heavier.

diabloridr

How about something cheaper and more durable?

Dean V

I never thought a good quality 10sp chain was that expensive, and not much different to a good quality 1/8" chain.
As for durability I have always found them to last a long time.
Overall a small % of the cost of keeping the bike on the road.

diabloridr

Our only experience is with the SRAM Red stuff on the stoker's single, everything else we own is Shimano 9-speed.

She managed to wear out a PC 1091R in one year (maybe 3000 miles of riding), replacement of 9-speed stuff on her old bike was much longer, so much so I don't keep track. Let's just say 2 years to be conservative.

Cost wise, I pay $30 to $40 for my 9-speed chains, the PC 1091R routinely goes for $80, though I scored a couple on Amazon for $53 each.

Hope she doesn't wear the cassette just as fast, SRAM XX cassettes are going for almost $300 <gag>

As always, YMMV.

jacks1071

I've decided to leave the 10sp chain on there for now - when the sprockets are worn out I'll consider fitting track sprockets and chain.

The track sprockets being a little wider should be more durable and the chains I am sure would take a lot more breaking.

I don't think there would be much performance gain in the lighter 10sp chain, anything we are gaining in weight I think is probably lost in flex. The drive train seems pretty flexy and I think the timing chain is the source of 70% of that flex.

The rear chain I can do nothing about since I want to run 10sp.

I'm surprised its not something more people have done.

I've read some more on the belt drives and I am positive I want to stick with a chain setup.

chas58

Sounds like you are doing the right thing.

Track chains and chain rings are incredibly strong. Keep in mind track chain rings are 144BCD, and you are unlikely to find 1/8" chain rings in 130 BCD. The 1/8" chain would work fine on a 3/32" chain ring though.

jacks1071

Anyone know if Davinci can supply the timing rings in 1/8" with their cranksets? I've emailed them but no reply yet. I noticed on the weekend that the spiders and the chain rings on the rear crank are a bit bent. I've straightened them out as best I can but we are up for a new crank sometime in the not so distant future.

TandemGeek

They and just about everyone else in the bicycle business is at Interbike in Las Vegas this week.

https://www.interbike.com/

jacks1071

I'll have to be patient then :-) Funny they should have a bike show in what must be one of the most bicycle unfriendly places in America. We spent sime time in Las Vegas last November and the drivers there were among the worst in the world. I didn't see one propper cyclist the whole week we where there.

sch

8spd chain is quite strong, dirt cheap compared with 10spd and works very well. Since the timing chain is an inline chain that never shifts the failure rate is much lower
than drive chain. Carrying a Park chain tool, a couple of spare links and quick connects for both the timing and drive chains costs only about 3 oz and gives a lot of
peace of mind. Nothing like being 50 miles out with a broken chain, been there. We just changed our TC for the first time at 13 kmi. We are on our 5th drive chain
(10spd DC). We reversed the timing CW a few thousand miles back. Weight difference 8->9->10spd chains is negligible, typically less than 30 grams.

jacks1071

Still no reply from Davinci - what are my other top end crank options? Should I re-consider the belt drive given that I'm replacing the cranks?

I had origionally discounted the belt drive option but now that our rear crank is bent and I'm thinking of replacing the set maybe its worth re-considering?

chas58

The biggest problems with a belt is getting it through the frame, and not being able to change gear ratios. Those are not an issue in this case. It might be an interesting option. Hmmm....

TandemGeek

Give them a phone call if you're anxious to communicate: (303) 936-1241

Most of the tandem builders are very small firms with little or no admin staff. If you really, really, really need to reach someone at a tandem manufacturer the best bet is ALWAYS picking up the phone.

I suspect they're still buried from Interbike and sifting through and prioritizing their Email.

wheelspeed

Jacks- Are you still having chain problems? It seems you found several reasons for your first mishap, between a bad chainring, re-using a chain because it was 'new' even though it may have been damaged, and finding your spyder with some misaligned tabs. If you've corrected those, and now you haven't had more problems, then you may want to consider this whole subject closed. At least until you have another problem, if you do.

Of course, sometimes it's nice to have an excuse to go shopping! (I know all about that.)

jacks1071

The only issue we still have is if we are on the middle chainring, and we are getting towards the smaller sprockets on the rear cassette like the last 3 gears - the chain will sometimes jump between the middle and big rings and slip.

I am guessing the BB probably needs to be wider as the chainline gets very crossed up.

I've also had to bend the chainrings to get them as straight as possible - they arn't perfect but reasonably good.

I'm still looking to replace the cranks though for something stronger and I'd like shorter cranks for the rear as we have 175 all-round at the moment and the stoker is only 5ft tall.