Mixing and matching ISO and JIS Square Taper BBs
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Mixing and matching ISO and JIS Square Taper BBs
I like to ride Campagnolo 10 speed triple setups (like the feel and mechanisms of Campagnolo and like the range of a triple).
For one of my current bikes, the FD (campagnolo 10 speed triple FD), the FD can't quite get out far enough (with the limit bolt as loose as can go) to shift from the middle to the big ring. If I push the chain a little with my finger, it'll go to the big ring and the cage is positioned nicely for it to stay on the big ring once there, but I just can't get it to shift to the big ring.
I've used the Campagnolo FD alignment tool to make sure the FD cage is straight and high enough, it just doesn't get quite there. Which makes me think that, for whatever reason, the crankset (Campagnolo Centaur Triple) is just a bit too far outside. Since it's a Campagnolo crankset, it's ISO square taper.
I've been using a Centaur 111 mm ISO BB. When the chain is on the little ring, there is plenty of clearance (at least 5 mm) to the chainstay. My thought was to try a BB with a shorter axle. Unfortunately, because square taper is so long out of use (and ISO even moreso - and Italian threaded even more yet), when I go looking for ISO BBs, my 3 choices appear to be 115, 111, and 102. While there is some room between the chain on the inner ring and the frame, dropping down 9 mm looks like it might be too much.
While searching for a BB in the 107 to 109 range, I remembered reading (and looked it up again) that Sheldon Brown had said that because the sloping of ISO and JIS square tapers were different, you could use a JIS BB on a square taper crank and it would push the crank ~4mm out and using a JIS crank on a ISO BB would push it ! 4 mm in.
Has anyone tried this? Would using a 103 mm JIS BB position my ISO crank as if it were on a 107 mm ISO Crank? Also, would there be enough engagement between the crank and the BB that it wouldn't ruin the crank?
What I really wish was there was a FD adapter that would just push the FD out a couple mm from where it is now (Braze-on Mount FD with an adaptor - OmniRacer - because it's a non-braze on frame). IF someone knows of one of those instead, I'd happily do go that route.
For one of my current bikes, the FD (campagnolo 10 speed triple FD), the FD can't quite get out far enough (with the limit bolt as loose as can go) to shift from the middle to the big ring. If I push the chain a little with my finger, it'll go to the big ring and the cage is positioned nicely for it to stay on the big ring once there, but I just can't get it to shift to the big ring.
I've used the Campagnolo FD alignment tool to make sure the FD cage is straight and high enough, it just doesn't get quite there. Which makes me think that, for whatever reason, the crankset (Campagnolo Centaur Triple) is just a bit too far outside. Since it's a Campagnolo crankset, it's ISO square taper.
I've been using a Centaur 111 mm ISO BB. When the chain is on the little ring, there is plenty of clearance (at least 5 mm) to the chainstay. My thought was to try a BB with a shorter axle. Unfortunately, because square taper is so long out of use (and ISO even moreso - and Italian threaded even more yet), when I go looking for ISO BBs, my 3 choices appear to be 115, 111, and 102. While there is some room between the chain on the inner ring and the frame, dropping down 9 mm looks like it might be too much.
While searching for a BB in the 107 to 109 range, I remembered reading (and looked it up again) that Sheldon Brown had said that because the sloping of ISO and JIS square tapers were different, you could use a JIS BB on a square taper crank and it would push the crank ~4mm out and using a JIS crank on a ISO BB would push it ! 4 mm in.
Has anyone tried this? Would using a 103 mm JIS BB position my ISO crank as if it were on a 107 mm ISO Crank? Also, would there be enough engagement between the crank and the BB that it wouldn't ruin the crank?
What I really wish was there was a FD adapter that would just push the FD out a couple mm from where it is now (Braze-on Mount FD with an adaptor - OmniRacer - because it's a non-braze on frame). IF someone knows of one of those instead, I'd happily do go that route.
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If your FD can't go out far enough. Then does the crank you are using have the correct chain line for the rear cassette?
Or is the Campy FD not the correct FD for that bikes rear spacing and required chain line?
Though you say it's Campy with Campy. So maybe it's just that you don't have the cable attached properly to the FD that it won't go out far enough. Or have you verified that by detaching the cable and moving the FD with your fingers.
Or is the Campy FD not the correct FD for that bikes rear spacing and required chain line?
Though you say it's Campy with Campy. So maybe it's just that you don't have the cable attached properly to the FD that it won't go out far enough. Or have you verified that by detaching the cable and moving the FD with your fingers.
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Not sure I've tried with the cable detached, but I have tried putting the shifter all the way to the inner ring and then pulling on the cable with my hands and haven't been able to get it far enough outward.
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There are quite a few Shimano FD's that if the cable wasn't properly routed and put in the pinch bolt the correct way they wouldn't go out far enough. They even had some models that came with a fixture you had to use at installation time to see if your cable had the proper routing and if not, you had to reposition a switch on the FD.
I've no idea if Campy ever had similar issues.
I've no idea if Campy ever had similar issues.
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The 1990s Campy Ergo levers can have an issue with the lever (the G springs engaging the index wheel) being able to hold that last click of the front lever when shifting into the big ring. Ders that have strong return springs and/or worn G springs (and ultimately the index wheel) make this more likely. The symptom can be the lever will throw the der as far as the lever's range will allow for but will settle "back" one click" and the lever will have that last bit of travel still remaining. I doubt this is the problem but...
IIRC the JIS taper share the taper angle but not how wide across the taper it is. I believe the JIS is slightly wider. So a JIS taper axle will snug up in a ISO crank arm but not quite as far into the tapered hole. There are two considerations here. One is if there's enough overlap between the JIS axle and ISO crank arm to transfer the power without any tapered hole degradation. IME there usually is but one needs to pay greater attention to the arm's retaining bolt's tightness as it could change with greater axle seating into the hole with use. Second is that for the same length JIS axle the ISO arm will sit further out. By how much is not a precise science as the tapers do have some tolerance and the Al arm will see some tapered hole wear.
Generally I aim for a couple/three MMs of inner ring clearance, just be sure the arm ends still miss the stays. Andy
.
IIRC the JIS taper share the taper angle but not how wide across the taper it is. I believe the JIS is slightly wider. So a JIS taper axle will snug up in a ISO crank arm but not quite as far into the tapered hole. There are two considerations here. One is if there's enough overlap between the JIS axle and ISO crank arm to transfer the power without any tapered hole degradation. IME there usually is but one needs to pay greater attention to the arm's retaining bolt's tightness as it could change with greater axle seating into the hole with use. Second is that for the same length JIS axle the ISO arm will sit further out. By how much is not a precise science as the tapers do have some tolerance and the Al arm will see some tapered hole wear.
Generally I aim for a couple/three MMs of inner ring clearance, just be sure the arm ends still miss the stays. Andy
.
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I'll probably just take it into the shop and make sure I have everything routed right before I do anything just to make sure. Hopefully, there's something obvious about the routing that I'm missing. For whatever reason, I have a lot harder time getting my FDs adjusted than my RDs.
The ergo bodies are fairly new (swapped the single click powershift Centaur for the ability to shift multiple gears at once with the record ultrashift - still has the original Centaur brake lever, but everything else is 6 months old).
The ergo bodies are fairly new (swapped the single click powershift Centaur for the ability to shift multiple gears at once with the record ultrashift - still has the original Centaur brake lever, but everything else is 6 months old).
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Ooh you had me excited (my wallet not so much), but it looks like they only do English Threaded (68/73) for the cartridge bearing. Could look into getting a spindle from them and then finding a vintage cup/cone. Probably better to take it to the shop first and see if I've done something incorrectly first rather than that I have a setup so unusual.
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the adapter rings are typically 20-40 bucks per set. The BB itself does not have threads, just "shoulders" on which the adapter rings sit.
/markp
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I made a gravel bike from parts. It had 10sp Campagnolo Chorus crank and a Shimano/Microshift drivetrain. The chainline was a wee bit medial of where it should be. The native Campy bearings weren't sealed and were rather old at this point. I used this as an excuse to get one of those super shiny IRD bottom brackets. If I recall, I got one one about 4mm shorter than I would have needed in ISO. It worked perfectly
It was 1x, so it didn't need to shift. Once it was dialed though, no chain drops. That part took some time though.
I don't know if that answers your question. Yes they're close enough to fit together. They don't randomly loosen. Nothing exploded. Just gotta account for the difference in where it would tighten to.
I do wonder if a JSO BB would deform an ISO crank, so that once you made the swap you can never go back. I don't know, I didn't try.
It was 1x, so it didn't need to shift. Once it was dialed though, no chain drops. That part took some time though.
I don't know if that answers your question. Yes they're close enough to fit together. They don't randomly loosen. Nothing exploded. Just gotta account for the difference in where it would tighten to.
I do wonder if a JSO BB would deform an ISO crank, so that once you made the swap you can never go back. I don't know, I didn't try.
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I don't know if that answers your question. Yes they're close enough to fit together. They don't randomly loosen. Nothing exploded. Just gotta account for the difference in where it would tighten to.
I do wonder if a JSO BB would deform an ISO crank, so that once you made the swap you can never go back. I don't know, I didn't try.
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On another thread, someone on here mentioned that you can increase front derailleur travel by removing some metal where the limit screw contacts (and when the screw is fully retracted, the linkage parts will touch there so take than into account). If possible, best to remove metal on the side where the screw end contacted, rather than the part with the threaded hole, as you don't want to shorten those threads if possible.