Go Back  Bike Forums > Bike Forums > Tandem Cycling
Reload this Page >

Intermediate Shaft on daVinci tandem

Notices
Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

Intermediate Shaft on daVinci tandem

Old 07-19-21, 07:38 AM
  #26  
Alan_F
Senior Member
 
Join Date: Jul 2017
Location: Maryland
Posts: 52

Bikes: DaVinci Joint Venture Ti S&S, DaVinci Symbiosis 27.5", DaVinci Symbiosis XC 29", Motobecane Century Ti ETap AXS, Motobecane Fantom Ti hardtail, Diamondback Haanjo Carbon, Motobecane Fantom 4x4 29'er, SE F@R fatbike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Likes: 0
Liked 8 Times in 7 Posts
Originally Posted by jethro00 View Post
I tested it. After I replaced the right grip shifter, all 3 chains, cassette, and 2 timing chainrings, a chain was still grinding and slipping. Now that I replaced the 3 sprockets on the intermediate shaft, it is not slipping. That suggests the sprockets on the intermediate shaft were worn. The bad news is that it is still making a grinding noise. The chains all look seated on chainrings and the cassette. What could cause the grinding sound?

There is one likely candidate left. If you had enough miles on the chains, the freewheels on the double freewheel block (DFB) may be worn and grinding on the new timing chain. I had this happen back in December when I replaced the rear timing chain after about 8,000 miles. The chain never measured any significant wear on a chain checker, but the chain/freewheel combination had clearly worn out. The stoker's timing chain made a horrible grinding sound under any sort of load, and the sound went away when I swapped the old chain back onto the bike. I ended up buying a new DFB from DaVinci and rode with the old chain until it arrived. If you don't mind a little downtime you can just send them the old one and they'll swap the freewheels and send it back to you, which would be less expensive. You could also just buy new freewheel cogs to install on the DFB but replacing those requires a special tool. I sent my old DFB back to have the freewheels replaced after the new one arrived so that I now have a spare.

My new maintenance plan is to use two sets of chains and swap the chains every 500 miles. I'm hoping I'll be able to extend the life of all the other drivetrain parts by doing that. I was going to go 1,000 miles between swaps, but my last drive chain was already worn to the point of needing to be replaced at 1,000 miles, so I'm switching to a 500 mile interval. I use the gear tracking function in Strava to keep tabs on the mileage of the individual parts.

Pro tip (from an amateur) - always hang on to your old chains when replacing them until you've got a few miles in on the new ones, assuming the bike was functioning ok before the change. That way when you realize other parts are worn (cassette, chainrings) you can just go back to the old chains while you source new parts. Like most things that I know, this was learned the hard way when I changed a chain on a tandem (non-Davinci drivetrain) before a week-long tour and then found the middle chainring was slipping under load with the new chain. I was lucky to be able to track down a chainring before the week was out, but the next time I found myself replacing a chain just before a tour I packed the old chain and took it with us just in case. Of course if I was smart I'd make sure that I wasn't doing maintenance before a big ride if I'm not going to have time to do some shake-down miles first.
Alan_F is offline  
Old 07-19-21, 08:27 AM
  #27  
jethro00
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Likes: 0
Liked 13 Times in 12 Posts
I will test tonight or tomorrow and report back about when it does and does not grind.
For now, I can provide additional information about how this got started and I have a question. We got the Grand Junction in the summer of 2016.
Until late last year, we rode the Grand Junction every day for about 45 minutes (75 minutes on Sundays). We started to get chain slip (but not grinding) when going up a hill or pushing hard on the pedals. At that time, I did not know to check for chain stretch. I got a chain gauge and learned that the chains were stretched. I got a set of chains from daVinci. After installing the new chains, we got chain slip and grinding and could not ride it. That's when I embarked on my odyssey of sourcing a cassette and chainrings and replacing them. Yesterday, I got no slip, but constant grinding upon pedaling.

My question is about having the bearing above center when adjusting the EBBs to ensure the set screws are pushing into the thick part of the EBB, not the thin part near the bearings, which would result in premature bearing wear. I use an Allen wrench to loosen and tighten the eccentrics. Should that set screw be rotated so it and the series of holes around it be above a horizontal diameter of the EBB?

Thanks.
jethro00 is offline  
Likes For jethro00:
Old 07-19-21, 05:11 PM
  #28  
Joint Venture
Senior Member
 
Join Date: Sep 2017
Posts: 82
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 25 Post(s)
Liked 4 Times in 4 Posts
I donít know when da Vinci changed the design of their eccentric. Our 2001 had the old school style where the eccentric was fixed in place by set screws in the frame located under the BB shells. Our 2016 doesnít have the set screws going through the BB shell but rather the eccentric expands to fit tightly in the BB shell by inserting a hex wrench in through the side and turning to tighten and loosen. It sounds like maybe jccaclimber has the old style eccentric design and you have the newer one. The newer design removes the concern of having set screws driving smack into the eccentric straight on. I have set my crank axle both in the lower and in the higher position (to provide more rear bar height by having to raise my saddle) with no issues at all. Even if you have the new expandable eccentrics, though, you may still need new BBís.
Joint Venture is offline  
Old 07-19-21, 05:16 PM
  #29  
jccaclimber
Senior Member
 
Join Date: May 2005
Location: SFBay
Posts: 2,009

Bikes: n, I would like n+1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Likes: 0
Liked 27 Times in 22 Posts
Correct, I have an old style eccentric. I forgot that design had changed, disregard that portion of my comment, it is not relevant to the newer bikes.
jccaclimber is offline  
Old 07-20-21, 08:33 AM
  #30  
jethro00
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Likes: 0
Liked 13 Times in 12 Posts
We were able to take a test ride this morning.
As with my previous solo test ride, there was no chain slip.
So, that continues to make me believe the 3 sprockets on the intermediate shaft needed to be replaced.
Here is the data on the grinding in-line below in red in response to Jccaclimber's questions.


<<As for your grinding noise, it shouldn't be hard to track down, although we need a bit more information.
1. Is it coming from the front of the back or the rear? It seems to be located at the front.
2. Does it happen when both people pedal, when just one pedals, or when coasting? It does not make the grinding noise when coasting or when just the stoker pedals. It only makes the grinding noise when the captain pedals and it constantly makes the grinding noise when the captain pedals, whether or not the stoker also pedals.
3. Does it happen if you are not on the bike, ie with the rear wheel off the ground and you are turning one of the cranks by hand? I have a 2 sided kick stand that makes this very easy for me to test, but a stand, flipping the bike over, or having someone hold it up for a moment would all serve the same purpose. It does not happen with the bike on the stand or up on the 2-sided kickstand.
4. Does it happen in every gear, or just some of them? It happens in every gear.
5. What if you spin the intermediate shaft backward by hand (on the output side), without the rear wheel moving? It's not quiet when I spin the intermediate shaft backward by hand, but it's not a grinding sound.
6. Are all the bearings smooth? This is easier to check in the BBs if the chains (or drive side cranks) are not installed, but removal is not required.
I don't know. How do I check that?
jethro00 is offline  
Old 07-21-21, 02:28 AM
  #31  
jccaclimber
Senior Member
 
Join Date: May 2005
Location: SFBay
Posts: 2,009

Bikes: n, I would like n+1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Likes: 0
Liked 27 Times in 22 Posts
Originally Posted by jethro00 View Post
We were able to take a test ride this morning.
As with my previous solo test ride, there was no chain slip.
So, that continues to make me believe the 3 sprockets on the intermediate shaft needed to be replaced.
Here is the data on the grinding in-line below in red in response to Jccaclimber's questions.


<<As for your grinding noise, it shouldn't be hard to track down, although we need a bit more information.
1. Is it coming from the front of the back or the rear? It seems to be located at the front.
2. Does it happen when both people pedal, when just one pedals, or when coasting? It does not make the grinding noise when coasting or when just the stoker pedals. It only makes the grinding noise when the captain pedals and it constantly makes the grinding noise when the captain pedals, whether or not the stoker also pedals.
3. Does it happen if you are not on the bike, ie with the rear wheel off the ground and you are turning one of the cranks by hand? I have a 2 sided kick stand that makes this very easy for me to test, but a stand, flipping the bike over, or having someone hold it up for a moment would all serve the same purpose. It does not happen with the bike on the stand or up on the 2-sided kickstand.
4. Does it happen in every gear, or just some of them? It happens in every gear.
5. What if you spin the intermediate shaft backward by hand (on the output side), without the rear wheel moving? It's not quiet when I spin the intermediate shaft backward by hand, but it's not a grinding sound.
6. Are all the bearings smooth? This is easier to check in the BBs if the chains (or drive side cranks) are not installed, but removal is not required.
I don't know. How do I check that?
This narrows it down quite a bit. It's somewhere between the captain's feet and the DFB.
My first guess from your description is captain's timing sprocket or BB, but you already replaced the timing sprocket, and a bearing needs to be pretty bad to make a grinding sound. I find the easiest way to feel a BB bearing is to remove the crank arms and rotate the spindle or bearings by hand while side loading them a bit. If it's inconvenient to pull the cranks off (mine are self extracting) then at least pulling the chain off will get you close. A smooth bearing feels just that, silky smooth. There may be some very mild seal drag, but it's still smooth (and likely no seal drag on bearings that have been in service a while). A bad bearing often feels like someone put some sand in it, and the balls are running into it.

If it doesn't happen normally on the 2 sided kickstand, you could try pedaling with the rear wheel off the ground while dragging the rear brake, but that really shouldn't be much different than riding normally. I suspect you'll find that the grinding gets louder with load.

Because it doesn't seem to matter if the stoker is pedaling I don't expect an interaction between the two freewheels on the DFB.

As another poster pointed out, this points to the captain's freewheel being worn enough that the chain slides a bit as it engages each tooth. I'd replace them both. Before you do that though, can you give us a nice clear picture of the freewheels? It's probably actually a bit easier with the chain still on, but we also need to be able to see the teeth where there is no chain.
jccaclimber is offline  
Old 07-21-21, 11:28 AM
  #32  
jethro00
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Likes: 0
Liked 13 Times in 12 Posts
Well, the list of suspects has been trimmed to two. I'll pull the chains later this week and take pictures of the two freewheels and rotate the spindle. If that doesn't yield an answer, I'll search for Youtube videos on removing the cranks and learn a new skill
Can BB bearings be greased? I have a tube of Park Tool PPL-1 Polylube 1000 Grease.
jethro00 is offline  
Old 07-21-21, 03:51 PM
  #33  
jccaclimber
Senior Member
 
Join Date: May 2005
Location: SFBay
Posts: 2,009

Bikes: n, I would like n+1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Likes: 0
Liked 27 Times in 22 Posts
Originally Posted by jethro00 View Post
Well, the list of suspects has been trimmed to two. I'll pull the chains later this week and take pictures of the two freewheels and rotate the spindle. If that doesn't yield an answer, I'll search for Youtube videos on removing the cranks and learn a new skill
Can BB bearings be greased? I have a tube of Park Tool PPL-1 Polylube 1000 Grease.
It could be your pedal bearings as well, but IME you feel that but donít tend to hear it. I donít remember if you listed your crank type, but Iíll assume itís square taper for now. A picture will clear that up. If itís not self extracting (typically an 8 mm allen) then youíll need a crank puller. Not hat to use and not expensive, but it is critical the tool be fully installed by hand and used properly. The threads inside cranks are especially easy to strip out, in a not so reversible sort of way.

Cartridge bearings (at least the ones on my older Davinci) can be regreased, but once the bearings are crunchy itís better to just replace them. Todd sells them as a spare part, but they are a common bearing. Just donít replace them with the junk on Amazon.
jccaclimber is offline  
Old 07-21-21, 08:26 PM
  #34  
jethro00
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Likes: 0
Liked 13 Times in 12 Posts
According to the specs on daVinci's web site, the cranks are Sugino XD 175 front, 170mm rear.
jethro00 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.