Advertise on Bikeforums.net



User Tag List

Page 3 of 5 FirstFirst 12345 LastLast
Results 51 to 75 of 106
  1. #51
    Clipless in Coeur d'Alene twocicle's Avatar
    Join Date
    Mar 2012
    Location
    Coeur d'Alene, Idaho
    My Bikes
    Calfee Tetra Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
    Posts
    1,168
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Turbotandem View Post
    If you go with the inboard mounting you will gain some stiffeness / responsiveness in the frame bottom tube. The closer to the centerline of the frame the less bending stresses are induced. If you have only 1mm, the sprocket and axle do deflect a bit so it is tight. I would put one of those clear 8mm protective film/dots on the stay right where the belt might rub, just in case.

    PS. When I used the term "inboard" in prior posts to refer to our bike, that is to mean inboard of the chain rings. A few makers have attempeted a belt installation outboard of the chain rings, but this induces so much bending in the frame so far from the center line. Better to put the belt on the left than to put it outboard of the chainrings on the right.

    DONE, well, sort of.

    I tweeked our rear Ultegra R603 crank alignment to allow the timing ring enough space + mud gap (more on this below) from the chainstay. However, our front Ultegra R601 crank timing alignment seems to be somewhere either left or right of the rear timing ring no matter which orientation (in or out), so I ended up with the front timing ring on the outside and then shifting the EBB a couple mm inward to achieve a close alignment with the rear ring. Having the rear timing ring mounted on the inside of the spider is probably the more important of the two, so mission accomplished there.

    Mud:
    Initial ride with the rear ring on the inner side was last weekend when road conditions were wet and very gritty. With only 1mm or so of chainstay clearance, accumulated muck on the chainstay was rubbing the side of the belt. Having now increased the clearance to +2mm I'm hoping that will be sufficient to avoid problems in mucky conditions. Should we encounter that problem again, stoker has been instructed to squirt the chainstay with water. Also, having framesaver tape at that spot proved very worthwhile.

    New observation about chainring bolts and no recesses in the CDX rings:
    The Ultegra chainring bolts supplied have a backing nut depth of only 4mm, while the CDX ring + Ultegra spider totals 7mm thick. As the CDX rings do not have a bolt head recess, the rings tend to float on the spider because the ring holes are much bigger than the bolt thread width and the nut is not long enough to reach through and hold the ring in place. If these rings had head recesses, that would help hold the rings in place, but without the recess the rings move around a lot until you tighten the bolts. With the rings floating around, trying to get them perfectly centered is a real hassle.

    Solutions:
    1) Flip the bolt/nut around so the nut (now on the outside) will hold the ring in a centered position (or if you mount the ring on the inside you can leave the bolt/nut in the normal orientation)
    or
    2) use longer chainring nuts. ie: for the Ultegra spiders, 5-6mm nuts in normal orientation will reach the timing ring and hold it in place.


    Your setup may vary. My comments above are based on experience with the Ultegra R601/603 cranks.
    Last edited by twocicle; 03-23-13 at 01:40 PM.

  2. #52
    Senior Member
    Join Date
    Sep 2009
    Location
    Central Illinois
    My Bikes
    Trek Speed Concept 9.9, 2011 Calfee Tetra Tandem
    Posts
    912
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Where are the pictures? And why did you do this?

  3. #53
    Clipless in Coeur d'Alene twocicle's Avatar
    Join Date
    Mar 2012
    Location
    Coeur d'Alene, Idaho
    My Bikes
    Calfee Tetra Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
    Posts
    1,168
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DubT View Post
    Where are the pictures? And why did you do this?
    Reason for inner mounting the rear timing ring per comments from Turbotandem above. FWIW, it's also explained in the PR info for the Paketa Vr2 (possibly the original source?) regarding advantages of moving the timing setup as far inward as possible.

    On our 2013 Calfee, alignment seems to work out better with the rear ring in and the front out. It was either mount the rings in this fashion, or else the original/normal mounting on the outside of the spider required addition of 2mm chainring spacers on the front ring to get the front/back alignment close enough.

    Gates made the ring holes far too large for typical chainring bolts to hold the rings firmly in place without a bolt head recess like most chainrings have, but a nut sleave will hold them fine when placed directly against the ring (or if you have sleaves long enough to reach through the spider arm. Here's a couple snaps of our CDX rings...

    First, is the rear ring on the inside of spider with bolt/nut in normal orientation:



    Next is the front ring mounted on outside of spider but with the bolt/nut reversed to hold the ring in place better:


    Wayne, if your crank nuts are 4mm like mine, and you mounted your rings on the outside with normal bolt orientation, then you can test this out... just loosen your ring bolts and see how much the ring moves. You'll see that it moves a lot. Then, flip the bolts/nuts around and do the same test. The ring should be much more stable on the spider arms because the nut sleave is just long enough to go through the ring plus catch the spider arm. I believe this helps get and keep the ring centered and shear torque is applied more to the nut sleaves rather than the bolt thread area.

    -

    BTW, moving the rear timing ring to the inside has another minor advantage (when either belt or chain is used)... clearance is improved for a stoker crank mounted computer magnet.
    Last edited by twocicle; 04-02-13 at 09:49 AM.

  4. #54
    Senior Member WNY tandem's Avatar
    Join Date
    Aug 2011
    Location
    Rochester, NY
    My Bikes
    Co-Motion Speedster, His & Her Trek Madone singles, Specialized Rockhopper
    Posts
    165
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I was able to mount both front and back rings on the inside on my Co-Motion Speedster

  5. #55
    Clipless in Coeur d'Alene twocicle's Avatar
    Join Date
    Mar 2012
    Location
    Coeur d'Alene, Idaho
    My Bikes
    Calfee Tetra Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
    Posts
    1,168
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by WNY tandem View Post
    I was able to mount both front and back rings on the inside on my Co-Motion Speedster
    Without more information, that is like saying "I have tires on my bike".

    1. Ring alignment. did your rings align perfectly OOTB, or how did you configure to achieve it?

    2. Crank symmetry. ie: how close are your cranks to being of equal distance from the BB center?

  6. #56
    Senior Member WNY tandem's Avatar
    Join Date
    Aug 2011
    Location
    Rochester, NY
    My Bikes
    Co-Motion Speedster, His & Her Trek Madone singles, Specialized Rockhopper
    Posts
    165
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by twocicle View Post
    Without more information, that is like saying "I have tires on my bike".

    1. Ring alignment. did your rings align perfectly OOTB, or how did you configure to achieve it?

    2. Crank symmetry. ie: how close are your cranks to being of equal distance from the BB center?
    but I do have tires on my bike! LOL

    Ring alignment: I installed a new set of FSA SL-K Light cranksets with the both Bottom Brackets installed centered with one Bottom Bracket spacer installed on each side. I did have to cheat the eccentric about 2cm to the right to align the Rings.

    Crank Symmetry: The Belt Rings are about 4.5cm from the center of the bottom bracket shell. The belt sits about 2cm from the chain stay.

  7. #57
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Crap...

    After seeing the black CenterTrack sprockets on a Calfee and a few other tandems at the Tandems East Expo two weeks ago, being pinged by brother USPSPRO on the results of our custom Gates belt test from a few year back, and then spending way too much time analyzing the drive train noise coming off our sync chain & rings during a Saturday ride this past weekend my interest in fiddling with the belts was piqued once again.

    Worse yet, I made the mistake of building a little spreadsheet-based table to figure out what size sprockets would be needed on our tandem to work with the 250t / 2000mm Gates CarbonDrive tandem sync belt. Son-of-a-***, if my math is correct it would appear 60t CDX sprockets would support a nearly perfect fit on our 30" boom tube.

    I've got questions into Gates as well as da Vinci to see if all of the various bits and pieces I'd need are available and if there's any past experience in mounting CDX sprockets to the da Vinci cranks to know if there would be any interference issues, i.e., can the sprockets be mounted either in-board or out-board on the da Vinci spiders.

    Debbie's gonna slap me up side the head if I mess with "her" tandem again.... but sometimes I just can't help myself. Inquiring minds 'need' to have answers to esoteric things such as the power of FARKLE.
    Last edited by TandemGeek; 04-01-13 at 10:49 PM.

  8. #58
    Tandem Mountain Climber
    Join Date
    Mar 2007
    Location
    San Mateo, CA
    My Bikes
    Calfee Tandem, Custom CAAD9 BB30, 90 Santana Arriva Tandem, 02 CAAD4 errand bike, 87 Cannondale "Black Lightning"
    Posts
    4,090
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TandemGeek View Post
    Crap...

    After seeing the black CenterTrack sprockets on a Calfee and a few other tandems at the Tandems East Expo two weeks ago, being pinged by brother USPSPRO on the results of our custom Gates belt test from a few year back, and then spending way too much time analyzing the drive train noise coming off our sync chain & rings during a Saturday ride this past weekend my interest in fiddling with the belts was piqued once again.

    Worse yet, I made the mistake of building a little spreadsheet-based table to figure out what size sprockets would be needed on our tandem to work with the 250t / 2000mm Gates CarbonDrive tandem sync belt. Son-of-a-***, if my math is correct it would appear 60t CDX sprockets would support a nearly perfect fit on our 30" boom tube.

    I've got questions into Gates as well as da Vinci to see if all of the various bits and pieces I'd need are available and if there's any past experience in mounting CDX sprockets to the da Vinci cranks to know if there would be any interference issues, i.e., can the sprockets be mounted either in-board or out-board on the da Vinci spiders.

    Debbie's gonna slap me up side the head if I mess with "her" tandem again.... but sometimes I just can't help myself. Inquiring minds 'need' to have answers to esoteric things such as the power of FARKLE.
    I'm thinking of having some davinci 130mm BCD 5-arm spiders machined, that would allow for any standard 130mm rings including the belt drive setup.

    Actually.... doesn't the main stoker spider have the same spline pattern as the timing gears? I could just order two of those from Davinci.

    Shame... I just got done drawing this to be CNC machined (note I didn't measure the square spline yet... it was just a placeholder).

    Last edited by uspspro; 04-02-13 at 06:05 AM.

  9. #59
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by uspspro View Post
    I'm thinking of having some davinci 130mm BCD 5-arm spiders machined, that would allow for any standard 130mm rings including the belt drive setup. Actually.... doesn't the main stoker spider have the same spline pattern as the timing gears? I could just order two of those from Davinci. Shame... I just got done drawing this to be CNC machined (note I didn't measure the square spline yet... it was just a placeholder).
    Yeah, you answered your own question regarding the da Vinci spiders. They have all of the key configurations and dimensions covered: Four Arm 104mm - 64mm, Standard 110mm - 74mm, and - Road 130mm (with 74mm triple option) in the Five Arm variety that bolt up to either drive or timing side cranks. In fact, I converted a set of 130mm BCD road cranks into 104mm off-road cranks for our Ventana back in 2002 using the interchangeable spiders. daVinci makes some really cool (and super light) stuff... and all of this stuff has been around since the mid-90s!

  10. #60
    Clipless in Coeur d'Alene twocicle's Avatar
    Join Date
    Mar 2012
    Location
    Coeur d'Alene, Idaho
    My Bikes
    Calfee Tetra Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
    Posts
    1,168
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If it were not for the square taper BBs, I'd be on board for the DV cranks.

    I'm curious if Todd or anyone else tested using a 24mm HTII/Mega style axle that threads into the drive crank instead of being permanently pressed in as those two mfr do? That way you could simply swap axle lengths to whatever you needed and still have the advantage of using outboard bearings and a much bigger/stiffer (and lighter?) axle.

    As far as CenterTrack feedback, it has been a "set it and forget it" experience. The belt is performing quietly and smoothly. After the expected install tweeking / learning curve, we have had no issues. Belt tensioning is a snap to do with external HTII BB cups, as rotating the EBB by hand is simple even without a pin spanner tool. For the most part, I haven't bothered with precise tensioning and just going by feel and plucking the belt to hear the tension pitch. Plus, not having to clean & lube a long timing chain has been a real pleasure.
    Last edited by twocicle; 04-02-13 at 10:38 AM.

  11. #61
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by TandemGeek View Post
    Son-of-a-***, if my math is correct it would appear 60t CDX sprockets would support a nearly perfect fit on our 30" boom tube.
    Doh! I forgot the tandem CarbonDrive / sync drive system and the regular Gates CarbonDrive / drive-side systems use belts and sprockets that have a different pitch: 8mm for the tandem application and 11mm for the drive-side.

    However, timing is everything -- no pun intended -- and it turns out Gates was already working to bring a 66t sprocket system to market this summer for Calfee & Cannondale that will work with a 30" boom tube dimension. So, I'll have to cool my jets until June when they become available via Gates or Calfee.

    I'm also told "no worries" on the daVinci cranks + 130 bcd spider + Gates sprockets; they work fine together. There has been some talk but no movement as of yet on a spiderless CDX sprocket for da Vinci. Wouldn't that be nice.

    I have no qualms about using square taper BB's. The day I / we can generate enough wattage or torque to bring BB axle deflection into play as a concern is the day I quit my day job and begin training for the Nationals & sign-on for the TransRocky challenge. I've only had one rear bottom bracket -- a very, very light Erickson Ti BB -- ever show clear signs of axle deflection. Never a hint of it with Shimano UN72s, UN73s, UN52s, Race Face TaperLock or our Phil Wood SS or Ti BB's. Being a lightweight, recreational team apparently has its advantages. Don't get me wrong, I like the simplicity of the MegaEXO, GigaPipe, Hollowtech and other crank interface systems, but I really get tired of hearing creaky tandems with under-torqued BB bolts or stories of chewed up BB bearings due to alignment or low-torque issues.

    Just my narrow view... as I look forward to June and some additional FARKLE for our tandem.

  12. #62
    Senior Member
    Join Date
    Sep 2009
    Location
    Central Illinois
    My Bikes
    Trek Speed Concept 9.9, 2011 Calfee Tetra Tandem
    Posts
    912
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by twocicle View Post

    As far as CenterTrack feedback, it has been a "set it and forget it" experience. The belt is performing quietly and smoothly. After the expected install tweeking / learning curve, we have had no issues. Belt tensioning is a snap to do with external HTII BB cups, as rotating the EBB by hand is simple even without a pin spanner tool. For the most part, I haven't bothered with precise tensioning and just going by feel and plucking the belt to hear the tension pitch. Plus, not having to clean & lube a long timing chain has been a real pleasure.
    I totally agree the belt is great, set it and forget it, I did use the iPhone app to set the tension. We just returned from a 3,000 mile road trip (tandem in the back of the Odyssey) and it was so nice not having to worry about a bag or suitcase toucing the tandem chain. The belt is clean!

  13. #63
    Gear Combo Guru Chris_W's Avatar
    Join Date
    May 2007
    Location
    Switzerland
    My Bikes
    Spec' Tarmac (road), Spec' Secteur Disc (commuter & tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder), a train pass, and NO car :)
    Posts
    2,090
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by twocicle View Post
    I'm curious if Todd or anyone else tested using a 24mm HTII/Mega style axle that threads into the drive crank instead of being permanently pressed in as those two mfr do? That way you could simply swap axle lengths to whatever you needed and still have the advantage of using outboard bearings and a much bigger/stiffer (and lighter?) axle.
    That sounds somewhat similar to Cannondale's Hollowgram cranks and axle - they have the bigger axle that is separable from both cranks. However, the bearings are internal and fit BB30 frames only. I've head of the system being referred to as "ISIS on steroids" - there are some similarities to ISIS, but with the axle and bearings way oversized and all separable.

  14. #64
    pan y agua merlinextraligh's Avatar
    Join Date
    Aug 2005
    Location
    Jacksonville
    My Bikes
    Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er
    Posts
    27,414
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TandemGeek View Post
    I have no qualms about using square taper BB's. The day I / we can generate enough wattage or torque to bring BB axle deflection into play as a concern is the day I quit my day job and begin training for the Nationals & sign-on for the TransRocky challenge. I've only had one rear bottom bracket -- a very, very light Erickson Ti BB -- ever show clear signs of axle deflection. Never a hint of it with Shimano UN72s, UN73s, UN52s, Race Face TaperLock or our Phil Wood SS or Ti BB's.
    I wonder how BB deflection compares on a tandem, versus a single, at least for the captain. The last square taper BB I had was on a single steel bike. I could definitely flex it to the point of inducing chain rub. However, my bet is that was more flex in the frame than the BB itself.

    My understanding is that one of the advantages of newer BB configurations is the larger BB shell, allowing designers to stiffen the frame around the BB.

    With a tandem, you've already got a large BB shell for the eccentric. Thus, my bet that the difference between square faced spindles, and newer systems doesn't result in much if any change in flex of the entire system.


    Also , old sqaure taper BB's still have about the lowest friction of anything available.
    You could fall off a cliff and die.
    You could get lost and die.
    You could hit a tree and die.
    OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

  15. #65
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by merlinextraligh View Post
    Thus, my bet that the difference between square faced spindles, and newer systems doesn't result in much if any change in flex of the entire system.
    You're on the right track, at least by my way of thinking as it pertains to tandems. Of course, I could be completely out of mind too.

    Here's the deal: If someone has never done so, it's very eye-opening to put your tandem on a rear-wheel resistance trainer with the front wheel in a wheel chock and then to observe the left-to-right, back & forth movement of the entire front crank/eccentric bottom bracket assembly. It's rather significant and it makes perfect sense why there's that much movement: it's the most unsupported part of the frame in terms of lateral bracing with contributions to the overall amount of deflection you see coming from axle-to-axle contributors, such as the tires, wheels fork/rear stays + frame.

    So, given that deflection will come from the weakest links in the chain, what are the chances that it's that short, very stiff axle that's bending when pedal loads go into the cranks?

    The rear bottom bracket is a different story altogether since the rear bottom bracket axle on a cross-over crankset tandem is being pushed and pulled in four different directions; two directions per side and always in opposing directions left vs. right. Right side drive becomes more attractive here because at least the fore/aft forces have a bit of a cancelling effect.

  16. #66
    Tandem Mountain Climber
    Join Date
    Mar 2007
    Location
    San Mateo, CA
    My Bikes
    Calfee Tandem, Custom CAAD9 BB30, 90 Santana Arriva Tandem, 02 CAAD4 errand bike, 87 Cannondale "Black Lightning"
    Posts
    4,090
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    My wife's single bike has the last model of Record Triple cranks and a Record square taper BB. That thing spins like butter. They are also very durable.


  17. #67
    Senior Member WNY tandem's Avatar
    Join Date
    Aug 2011
    Location
    Rochester, NY
    My Bikes
    Co-Motion Speedster, His & Her Trek Madone singles, Specialized Rockhopper
    Posts
    165
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I broke down and purchased the Gates Carbon Drive Krikit Tension Gauge. I want to compare it's measurement against the iPhone App.

  18. #68
    Senior Member Bent In El Paso's Avatar
    Join Date
    Nov 2009
    Location
    El Paso, TX
    My Bikes
    Co-Motion Speedster Co-Pilot
    Posts
    187
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by WNY tandem View Post
    I broke down and purchased the Gates Carbon Drive Krikit Tension Gauge. I want to compare it's measurement against the iPhone App.
    Since I started using the app, I have never resorted back to the Krikit. I find the app to be much more repeatable. The whole key is to find the spot in the belt with the most tension and take the measurement in that same spot every time. Since I started using the app, my belt worries have been nonexistent. I set the tension to about 75 Hz and forget about it.

    Periodically the belt will begin to creak under pressure. That is when I know it is time to wipe it and the pulleys down with a wet rag. Since our riding is exclusively in arid climates, I think the dust and sand collects in the grooves of the belt where it is "packed" in as the belt goes over the pulley. Without moisture on the roads to periodically "wash" the belt during rides, this dust and sand just continues to accumulate until the belt gets noisy. If it gets real annoying during a ride, I will give it a squirt out of a water bottle and that will quiet it down for 10 miles or so.
    Fred

    Behind every good captain is a great stoker!

    Co-Motion Speedster Co-Pilot

  19. #69
    Clipless in Coeur d'Alene twocicle's Avatar
    Join Date
    Mar 2012
    Location
    Coeur d'Alene, Idaho
    My Bikes
    Calfee Tetra Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
    Posts
    1,168
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Bent In El Paso View Post
    Since I started using the app, I have never resorted back to the Krikit. I find the app to be much more repeatable. The whole key is to find the spot in the belt with the most tension and take the measurement in that same spot every time. Since I started using the app, my belt worries have been nonexistent. I set the tension to about 75 Hz and forget about it.

    Periodically the belt will begin to creak under pressure. That is when I know it is time to wipe it and the pulleys down with a wet rag. Since our riding is exclusively in arid climates, I think the dust and sand collects in the grooves of the belt where it is "packed" in as the belt goes over the pulley. Without moisture on the roads to periodically "wash" the belt during rides, this dust and sand just continues to accumulate until the belt gets noisy. If it gets real annoying during a ride, I will give it a squirt out of a water bottle and that will quiet it down for 10 miles or so.
    We had one super gritty, wet ride where maybe every moving part on the bike started making ugly noises, so I can't say if the belt was contributing or not.

    Maybe a belt treatment spray would help... silicone or something. Call Gates support and ask, then report back here.
    Last edited by twocicle; 04-04-13 at 02:51 PM.

  20. #70
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by twocicle View Post
    Maybe a belt treatment spray would help... silicone or something.
    Y'all just need to brush your teeth once in a while!

    We saw (OK, heard) the same thing during our small-pulley testing. A soft bristle brush with soapy wash water did the trick.

  21. #71
    Senior Member Turbotandem's Avatar
    Join Date
    Nov 2011
    Location
    Boulder, CO
    My Bikes
    Paketa V2r di2, C-Dale MT 3000, Teesdale, 1963 Huffy Daisey
    Posts
    165
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    [QUOTE=TandemGeek;15459733]... it turns out Gates was already working to bring a 66t sprocket system to market this summer fora 30" boom tube dimension.[QUOTE]

    Note that as the sproket gets smaller the tension in the belt goes up and therefore the deflection induced in the bottom tube. I don't know how to calculate the percent differnce between, say, 74t, 69t and 66t.

    I have no qualms about using square taper BB's. The day I / we can generate enough wattage or torque to bring BB axle deflection into play as a concern is the day I quit my day job and begin training for the Nationals & sign-on for the TransRocky challenge. [QUOTE]

    I knew a strong team once that swisted the stokers square taper axle from the captains power. Saw the result myself.

    Quote Originally Posted by twocicle View Post
    Maybe a belt treatment spray would help... silicone or something. Call Gates support and ask, then report back here.
    I use a dry film silicone spray meant for timing belts in a car engine. Works very well. Spray liberally once every month or two if I get any squeeks from belt squirm.
    Andy
    Boulder Colorado

  22. #72
    Gear Combo Guru Chris_W's Avatar
    Join Date
    May 2007
    Location
    Switzerland
    My Bikes
    Spec' Tarmac (road), Spec' Secteur Disc (commuter & tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder), a train pass, and NO car :)
    Posts
    2,090
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by twocicle View Post
    We had one super gritty, wet ride where maybe every moving part on the bike started making ugly noises, so I can't say if the belt was contributing or not.

    Maybe a belt treatment spray would help... silicone or something. Call Gates support and ask, then report back here.
    Our CenterTrack timing belt makes some noise after each extended section of dirt road. A couple of quick squirts from the water bottle doesn't quiet it down. Some continuous squirts from a full 750 ml water bottle while back-pedalling until the bottle is empty always does the trick (but I have to wait until we find a water fountain to do this so that we don't waste a valuable bottle of water). This is fine on a road/touring bike that only occasionally encounters dirt roads, but it makes me wonder how mountain bikers cope who are using the system - they must have an almost-permanently noisy drivetrain!

  23. #73
    Senior Member Turbotandem's Avatar
    Join Date
    Nov 2011
    Location
    Boulder, CO
    My Bikes
    Paketa V2r di2, C-Dale MT 3000, Teesdale, 1963 Huffy Daisey
    Posts
    165
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    For those following sprokets here but not reading the di2 thread, I'll repost here:

    Below is the production version of Paketa's proprietary, 69 gram, adaptor. This is hot off the CNC line for mating a right side belt drive 130bcd gates sproket with a 110bcd compact crank, and a 52t and 34t chainrings in our case. At NAHBS 2013 the protoype was revealed as an option for the V2r. I'd previously posted a picture of that prototype in use on our bike, but it was hard to appreciate without removing the crank. And the final version now looks much more refined. It adds a lot of flexibility even if a team didn't want 34t inner ring, the adaptor works for any 110bcd set up, say 54-38, or 52-34 as we have. I don't think any other builders have solved a right side belt, so the details of the adaptor are not something most will need. But is is a beautifully solved bit of engineering, and the machining is sweet. Chaulk up another point for the custom world of high performance tandems where few things are off-the-shelf. Both normal chainring nut and bolts, and 12mm chainring bolts are involved in the assembly. Here, the adaptor is mating a CDC sproket, but it is also designed to propery space with a CDX sprocket. Since the belt for CDC and CDX is the same just with a groove, the front cranks use a CDX sproket to manage the drift of the belt(not pictured)

    compact adaptor ver 2.jpg
    adaptor on itw own.jpg
    Andy
    Boulder Colorado

  24. #74
    Tandem Mountain Climber
    Join Date
    Mar 2007
    Location
    San Mateo, CA
    My Bikes
    Calfee Tandem, Custom CAAD9 BB30, 90 Santana Arriva Tandem, 02 CAAD4 errand bike, 87 Cannondale "Black Lightning"
    Posts
    4,090
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Turbotandem View Post

    I knew a strong team once that swisted the stokers square taper axle from the captains power. Saw the result myself.
    It can happen to any axle: (this is a DA 7900)


    Worn/failed bearings are big contributors to axle damage.

  25. #75
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,162
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by Turbotandem View Post
    Note that as the sproket gets smaller the tension in the belt goes up and therefore the deflection induced in the bottom tube. I don't know how to calculate the percent differnce between, say, 74t, 69t and 66t.
    Yes, it does and we have a little bit of experience with running very small sprockets & belts on our Calfee.



    They ultimately proved to be too small to be practical and were a bit problematic given the force they generated on the bottom bracket axles. But, that's in part what the experiment was investigating; how small is too small.



    66t sprockets would be even a bit larger in diameter than the 34t da Vinci timing rings we've been using on all of our road tandems since 1998 and on two different Ventana off-road tandems since 2000. Given that we've never had any issues running 34t timing rings relative to excessive deflection at the boom tube or accelerated wear and tear of the bottom brackets (square taper on all five of the tandems that have used the daVinci cranks & 34t rings), I have no concerns about the 66t sprocket coming out this summer. 100% static tension is another issue altogether and only time will tell what the long-term effects might be, but that would be the same for any tandem riding a sync belt. Again, as for driven loads generated by a belt system I don't see them being any higher than an equivalent diameter chain system as I'm convinced the sync belts are performing more-or-less like a chain where the upper run carries most of the load vs. a true synchronous drive belt system where it distributes the load on both / all spans. Harley's aren't all that different under hard acceleration as you can see their lower belt runs flopping around.
    Last edited by TandemGeek; 04-05-13 at 06:02 AM.

Page 3 of 5 FirstFirst 12345 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •