Going from a triple to a double – what don’t I know?

[drevil]

@EasyRider 159007 wrote:

Since drevil is my ask-questions-guy, does that mean that chainline on two-piece cranks/external BB is not at all adjustable? I do like that about square taper cartridge spindles … you can use them on all sorts of bikes. If the chainstays are wide or narrow, you just get a wide or narrow cartridge so they don’t hit the chainstay. Varying spindle length is also useful for fixed gear conversions.

Haha, thanks?

Chainline (i.e., lateral adjustment) is adjustable on external BBs by varying the spacers on each side between the frame and BB cup. Quick Googz has this pictorial with decent pics of how to do it:
http://cycleseven.org/hollowtech-ii-chain-line-and-q-factor

As for narrowing the width (or tucking the crankarms closer to the frame) for a lower Q factor, I don’t think that’s possible. With the external BBs and cranks I’ve worked with (Shimano XT, SLX, Middleburn), the Q is the Q is the Q

[EasyRider]

Pardon my ignorance … is chainline on 2-piece cranks adjustable, or does having an integrated spindle mean that it is what it is? Do 2-piece cranks typically have fairly wide tread/q-factor to accomodate a range of bikes, or are they pretty narrow/ergonomic?

Agree with drevil, the argument for 3-piece cranksets, including square taper, is versatility/adjustability. Almost any square taper crank can be used on almost any bike because BB spindle length and chainrings can be changed out.

Gonna do a 2 piece on my next build.

[huskerdont]

@TwoWheelsDC 159006 wrote:

Did a shop put it together? Maybe they just used a ton of grease to lube the shell and some has come out with pedaling pressure? I guess if it’s coming out of the bearing itself, that wouldn’t be a great sign…

Yes, this bike was purchased assembled. The only thing I’ve done to it is change the brakes on it to Spyres. I did not notice any grease prior to last night–in other words, I don’t think it was there originally, but that it has come out sometime during or after the Skyline ride Sunday.

[Harry Meatmotor]

@drevil 159005 wrote:

Six years ago… custom fat bike

As a mechanic, this notion, although cool, is the issue. The builder should’ve said something when only one company makes a suitable BB – what if Phil stops making them? or better yet, the builder should’ve been frank and said a 5mm difference in chainstay length is negligible and pushed out to 420mm. but that’s just my opinion.

The fat bike/plus bike/boost/boost+ standards are still kinda sorting themselves out BB spindle-length-wise. IMHO, it’s 90-95% of the way there. By MY18-19 I think things will mostly be settled out.

but, add to that the CX/Gravel conundrum that no single spacing standard yet (imho, after this year we’ll finally probably get there with a generic TA disc standard for all BB styles/frame materials for both “gravel” and CX), and I’d try to live within the parts envelope of “easy to find, or generally well stocked”.

[drevil]

@Harry Meatmotor 159013 wrote:

As a mechanic, this notion, although cool, is the issue. The builder should’ve said something when only one company makes a suitable BB – what if Phil stops making them? or better yet, the builder should’ve been frank and said a 5mm difference in chainstay length is negligible and pushed out to 420mm. but that’s just my opinion.

I’ve never heard of anyone breaking a Phil Wood spindle, and bearings aren’t terribly difficult to change if you have the right tools and knowledge (which I have).

Vertigo (aka Sean Chaney) is an innovative builder, and we both wanted a fat bike that was totally different than anything else at the time. When we were discussing the design in early 2011, most fat bikes until then were designed to be very stable, and work best in snow, sand, and soft conditions. I wanted a playful and snappy mountain bike that just happened to have fat 4″+ tires, and part of that meant designing the chainstays as short as possible. We didn’t know exactly what would work, but we knew that we could make something work (he’s also well versed in machining – he made these and this ). I knew what I was into, and Sean was very vocal during the whole build process. There was an issue later on*, but nothing that prevented me from riding the bike.

* – Apparently a titanium 155mm bottom bracket spindle flexes/bends more (thus creakier) than a steel spindle of the same size I now have the steel spindle in the bike, and the ti sits as an (expensive) backup because it talks too much.

[hozn]

So I’ve got a related question for the more-experienced on here from my current (new) coupler-frame gravel build.

For the new build I decided to go ahead and replace my RD with a Rival 1 long-cage so I could put a wider range cassette on there, since I already had over 5k on my previous cassette & chain and I don’t tend to get much more than that. I’m running 10sp, so I have an 11-40 Sunrace cassette. I’m using a KMC SL10 chain. My chain ring is a 44t Wolf Tooth N/W; it’s worn, but should have another cassette-worth of miles in it. (Around ~5k miles now)

(1) I’m having a hard time getting the RD to correctly put the chain on the big (40t) cog. It wants to be adjusted a little too far inboard compared to the rest of the cogs. It isn’t an issue with limit screw and I’ve played with the b-screw a bit to see if that has an affect (it might, but I couldn’t easily discern a difference).

(2) And then when I backpedal, I’m dropping the chain down at least one cog (sometimes a few cogs). This doesn’t feel great, though I don’t know how that will play out in practice. Backpedaling can be useful on technical stuff, though, and I kinda imagine that would be the sort of environment where I’d be using that cog.

For now I’ve downsized to an 11-36t cassette which seems better as far as the indexing is concerned, but still does drop the chain down a cog or two when backpedaling.

The chain line doesn’t look very good from that big cog. But a few things make this puzzling to me:
– I don’t think I had an issue with backpedaling on my previous frame, which was spec’d to have the same length chainstays (430mm). Different cassettes (11-36 Shimano XT) and chain (KMC 10.93). I have another Shimano cassette I might swap on just to see.
– I have checked and corrected my derailleur alignment. To be fair, I didn’t put back on the big cog cassette after making some tweaks to alignment, but since I still have chain dropping off the 11-36, I suspect that aspect is still in play for the larger one.

I’ve ordered a SRAM X-Sync chainring which will hopefully fix the issue by moving the chainline in by 2mm. I haven’t measured chain line on the new system, but it’s a double crank with the N/W ring on the outside. Should be the same as previous setup — same 68mm BB shell, etc.

Anyway, wondering if there’s anything else I should consider besides chainline with the chain falling off backpedaling. And maybe anything I’m not thinking of when it comes to things that affect chain line. Puzzled by how this could be different on a frame that is at least supposed to match dimensions exactly. I’ll start taking some measurements, I guess, to confirm that belief. Also puzzling that I don’t have any problems with my 40t cassette and a 50t ring on my road bike with 415mm stays (!)

[drevil]

@hozn 159019 wrote:

So I’ve got a related question for the more-experienced on here from my current (new) coupler-frame gravel build.

For the new build I decided to go ahead and replace my RD with a Rival 1 long-cage so I could put a wider range cassette on there, since I already had over 5k on my previous cassette & chain and I don’t tend to get much more than that. I’m running 10sp, so I have an 11-40 Sunrace cassette. I’m using a KMC SL10 chain. My chain ring is a 44t Wolf Tooth N/W; it’s worn, but should have another cassette-worth of miles in it. (Around ~5k miles now)

(1) I’m having a hard time getting the RD to correctly put the chain on the big (40t) cog. It wants to be adjusted a little too far inboard compared to the rest of the cogs. It isn’t an issue with limit screw and I’ve played with the b-screw a bit to see if that has an affect (it might, but I couldn’t easily discern a difference).

(2) And then when I backpedal, I’m dropping the chain down at least one cog (sometimes a few cogs). This doesn’t feel great, though I don’t know how that will play out in practice. Backpedaling can be useful on technical stuff, though, and I kinda imagine that would be the sort of environment where I’d be using that cog.

For now I’ve downsized to an 11-36t cassette which seems better as far as the indexing is concerned, but still does drop the chain down a cog or two when backpedaling.

The chain line doesn’t look very good from that big cog. But a few things make this puzzling to me:
– I don’t think I had an issue with backpedaling on my previous frame, which was spec’d to have the same length chainstays (430mm). Different cassettes (11-36 Shimano XT) and chain (KMC 10.93). I have another Shimano cassette I might swap on just to see.
– I have checked and corrected my derailleur alignment. To be fair, I didn’t put back on the big cog cassette after making some tweaks to alignment, but since I still have chain dropping off the 11-36, I suspect that aspect is still in play for the larger one.

I’ve ordered a SRAM X-Sync chainring which will hopefully fix the issue by moving the chainline in by 2mm. I haven’t measured chain line on the new system, but it’s a double crank with the N/W ring on the outside. Should be the same as previous setup — same 68mm BB shell, etc.

Anyway, wondering if there’s anything else I should consider besides chainline with the chain falling off backpedaling. And maybe anything I’m not thinking of when it comes to things that affect chain line. Puzzled by how this could be different on a frame that is at least supposed to match dimensions exactly. I’ll start taking some measurements, I guess, to confirm that belief. Also puzzling that I don’t have any problems with my 40t cassette and a 50t ring on my road bike with 415mm stays (!)

These are obvious, and you probably checked them already:

• The cogs of the new derailleur aren’t sticky and spinning smoothly
• The freehub freewheels smoothly and isn’t binding
• KMC chains: does it use a pin or quick link to put it together? If the former, there’s no binding?

BTW, I’ve had this problem on 2 mountain bikes where I backpedal and it drops from 42T cog. I fixed one, and live with the other.

[Harry Meatmotor]

@drevil 159017 wrote:

I’ve never heard of anyone breaking a Phil Wood spindle, and bearings aren’t terribly difficult to change if you have the right tools and knowledge (which I have).

Vertigo (aka Sean Chaney) is an innovative builder, and we both wanted a fat bike that was totally different than anything else at the time. When we were discussing the design in early 2011, most fat bikes until then were designed to be very stable, and work best in snow, sand, and soft conditions. I wanted a playful and snappy mountain bike that just happened to have fat 4″+ tires, and part of that meant designing the chainstays as short as possible. We didn’t know exactly what would work, but we knew that we could make something work (he’s also well versed in machining – he made these and this ). I knew what I was into, and Sean was very vocal during the whole build process. There was an issue later on*, but nothing that prevented me from riding the bike.

* – Apparently a titanium 155mm bottom bracket spindle flexes/bends more (thus creakier) than a steel spindle of the same size I now have the steel spindle in the bike, and the ti sits as an (expensive) backup because it talks too much.

I get all that, and it’s certainly cool, but I don’t see it as a viable case for saying to the OP: moving to an outboard BB and modern 2-piece/3-piece cranksets is a bad idea. A custom ca-2011 fatbike with super short chainstays is an outlier.

[drevil]

@Harry Meatmotor 159022 wrote:

I get all that, and it’s certainly cool, but I don’t see it as a viable case for saying to the OP: moving to an outboard BB and modern 2-piece/3-piece cranksets is a bad idea. A custom ca-2011 fatbike with super short chainstays is an outlier.

Oh, I never said that. Did I give that impression? I’m all for 2-piece cranks and much prefer them. Someone asked what reasons are there to use 3-piece cranks and I gave some reasons why.

[Harry Meatmotor]

@hozn 159019 wrote:

My chain ring is a 44t Wolf Tooth N/W; it’s worn… [snip] …Also puzzling that I don’t have any problems with my 40t cassette and a 50t ring on my road bike with 415mm stays (!)

without seeing the bike in the stand, this jumped out at me. Actual chainline is a compound “thing” – My guess is bringing the chainline in 2.5mm towards CL (on the 44T chainring bike) will help. But I’ve also seen bikes that did the same thing with new chainrings versus worn chainrings of the same size. Worn chainrings didn’t produce drops while backpedaling.

[hozn]

@drevil 159021 wrote:

These are obvious, and you probably checked them already:

• The cogs of the new derailleur aren’t sticky and spinning smoothly
• The freehub freewheels smoothly and isn’t binding
• KMC chains: does it use a pin or quick link to put it together? If the former, there’s no binding?

BTW, I’ve had this problem on 2 mountain bikes where I backpedal and it drops from 42T cog. I fixed one, and live with the other.

Thanks– good suggestions. I’ll double check the pulleys, but I believe they were all spinning fine. At first I didn’t have the chain seated correctly on the pulleys (they’re narrow/wide now on the Sram 1x derailleurs!), but that was quite immediately obvious. I’ll check the freehub, but I think it’s fine. This is a KMC with a quick link, no binding that I can tell.

Now that I’ve got that part done, I’ll ride it tomorrow and hopefully get a few more data points as it settles in.

[hozn]

@Harry Meatmotor 159025 wrote:

without seeing the bike in the stand, this jumped out at me. Actual chainline is a compound “thing” – My guess is bringing the chainline in 2.5mm towards CL (on the 44T chainring bike) will help. But I’ve also seen bikes that did the same thing with new chainrings versus worn chainrings of the same size. Worn chainrings didn’t produce drops while backpedaling.

That’s interesting — wonder if the worn cassette could have same issue re: drops. (I imagine it could.) . I’m tempted to put on a lightly worn XT 11-36t to see if that behaves differently than the new Sunrace 11-36t.

In the end if the new X-Sync ring fixes the problem, there isn’t much more to worry about. It just means I’ll stick with X-Sync or a setup that achieves similar chain line. In reality I spend 90% of the time in the bottom 3 cogs, so that’s probably the more important chain line to have right.

[hozn]

@hozn 159019 wrote:

So I’ve got a related question for the more-experienced on here from my current (new) coupler-frame gravel build.

For the new build I decided to go ahead and replace my RD with a Rival 1 long-cage so I could put a wider range cassette on there, since I already had over 5k on my previous cassette & chain and I don’t tend to get much more than that. I’m running 10sp, so I have an 11-40 Sunrace cassette. I’m using a KMC SL10 chain. My chain ring is a 44t Wolf Tooth N/W; it’s worn, but should have another cassette-worth of miles in it. (Around ~5k miles now)

(2) And then when I backpedal, I’m dropping the chain down at least one cog (sometimes a few cogs). This doesn’t feel great, though I don’t know how that will play out in practice. Backpedaling can be useful on technical stuff, though, and I kinda imagine that would be the sort of environment where I’d be using that cog.

For now I’ve downsized to an 11-36t cassette which seems better as far as the indexing is concerned, but still does drop the chain down a cog or two when backpedaling.

I’ve ordered a SRAM X-Sync chainring which will hopefully fix the issue by moving the chainline in by 2mm. I haven’t measured chain line on the new system, but it’s a double crank with the N/W ring on the outside. Should be the same as previous setup — same 68mm BB shell, etc.

So, switching to the 46t X-Sync ring did not help. That was disappointing.

Then I switched my cassette to the lightly used 11-36 XT cassette I had and the problem went away! The profile of the teeth in the big cog is a bit different; I guess that must be the difference! Anyway, I’m happy with the XT cassettes, so I’ll just keep using them.

[hozn]

@hozn 159251 wrote:

So, switching to the 46t X-Sync ring did not help. That was disappointing.

Then I switched my cassette to the lightly used 11-36 XT cassette I had and the problem went away! The profile of the teeth in the big cog is a bit different; I guess that must be the difference! Anyway, I’m happy with the XT cassettes, so I’ll just keep using them.

I’ve learned more about this than I thought I’d need to.

Here’s a great video on chain dropping when backpedaling: https://www.youtube.com/watch?v=H6bvQha4FPk

This prompted me to go ahead and replace my KMC SL10 chain with a SRAM X1 chain. Yeah, the X1 is 11sp and I’m running 10sp, but it seems to work fine. I also switched back to the 11-40t cassette. It still comes off backpedaling, but the behavior is better.

It’s odd, though, to have enough tension to keep it in the big cog (where chain is pulling at a bit of an angle), I have to adjust it so that I end up with some I-want-to-shift noise in the little cogs. I double checked that derailleur hanger is aligned; it is — at least within a few mm both vertically and horizontally. I did discover a loose derailleur hanger bolt, so I tightened that but it hasn’t changed the overall behavior. It only seems to happen with the 11-40t cassette; the 11-36t Sunrace cassette behaves just fine as far as the shifting indexes. That one did have chain fall off in packpedal too — I haven’t re-tested it with the X1 chain, but it wouldn’t surprise me if it’s fixed now.

The shifting noise is not making me happy, but it’s not too bad so I’m probably leaving it alone for now. I’d like the 40t for the gravel double metric Saturday.

I think I’m done with Sunrace cassettes, though. The SRAM or Shimano cassettes seem to be much better, at least when it comes to shifting. The Sunrace look blingy with their red carriers & spacers, but they’re noisy and the lack of big-cog tooth profiling leading to backpedal drops is pretty annoying. I just wish Shimano or SRAM made a 10sp 11-40. Maybe I’ll consider a Praxis or Hope 11-40 if I can find one on sufficient sale.

I suspect I could also solve the backpedal by swapping out my Rival double crankset for a Rival 1, but then I’d have more extreme chain line in the little cogs, which is where I do spend more time (but maybe the angles would matter less there since the cogs are smaller, making the effective contact points further apart).

[Harry Meatmotor]

@hozn 159496 wrote:

…but maybe the angles would matter less there since the cogs are smaller…

Ding Ding Ding!!!

It’ll be a bit noisier and there’ll be some hesitation dropping into the top 2 or 3 cogs, but cheating the chainline towards the BB with some chainring spacers will get you pretty damn close to fixing this. I’ve also noticed (at least on my 1x CX setup: Rival 40T XSync, Red 11-32 Powerdome, with Specs goofyass SCS crap) that running the chain a link or two long helps, too).

Also, didn’t want to say it earlier and make you feel bad, but IMHO too, Sunrace is kinda janky. Would not recommend.

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