V20 Build - MBB newbie

[dtseng]

Are you using 50-tooth big chainring? The problem is the hanger is placed too high on that little post. This problem has been discussed in S40 threads. I am surprised that the problem has not been corrected in the new V20 chain stay. I remembered that I read it some where that someone mentioned to leave it as is at 1 cm, it would shift OK. Some front derailleurs have two mounting holes, use the top hole would work.

 

[nobrakes]

Yes, 50T big ring. I’ll try it as-is and see how it goes. Also discovered that there’s not enough clearance on the 40T biggest ring on the cassette with the GX2.1 adjusted as far out as it can go, there’s still some interference. Is a wolf tooth the magic solution?

 

[nobrakes]

So I currently have about 8 usable gears on the small ring, the bike is otherwise complete. Decided it was enough to get started so put some lights on, my old MTB bear trap pedals and went out to do some drills in the dark round the village. Probably gave a few people a scare, lurching down the road on this strange black contraption.

Did some flintstoning, some freewheeling with legs in the air, some freewheeling with feet on pedals, felt totally weird at first but soon got used to it. Then did a bit of pedalling, moved on to some turns and then pedalled along the village to an empty car park to do some figure eights. Had a few death wobbles on the way, but relax and sit up, everything was kept under control.

After about 20 minutes I was comfortable pedalling figure eights, not exactly Olympic standard elegance but good progress nevertheless. Was feeling quite pleased when I got back - and my forearms are sore! That was with me making an effort to be relaxed.

The pedal steering wasn't anywhere near as bad as I thought it was going to be. Certainly no harder than learning to ride the Fuego and most of those skills have transferred across, particularly low speed turning leaning out of the turn etc. I think because it is a fairly reclined semi-low racer a lot of the balance stuff is already drilled in. I am not worried about the learning curve though after tonight, I can relax knowing that I can definitely get comfortable on this platform.

Only gripe I have is that the lid on the carbon race case makes an absolute racket. It rattles constantly - going to need to do something about that.

So I need to get my front derailleur working and extend the usable range of the rear derailleur. I believe it has the tooth capacity but there's a bit of hard interference on the larger rings of the cassette. Is this the extra that I need? https://www.wolftoothcomponents.com/collections/derailleur-optimization/products/roadlink

 

[Bill K]

I've been using the Wolftooth road link with an 11/42 cassette (DI2) for almost a year. It works pretty well but does not shift quite as crisply.
I like it better than not having low gears for the hills around here.

 

[ratz]

Only gripe I have is that the lid on the carbon race case makes an absolute racket. It rattles constantly - going to need to do something about that.

Go to the hardware store and get the special velcro they make for Fabric. It's much thinner than standard and has a bitter grip. You can the use thin strip of that in strategic place to make the lid stop rattling. I replaced all the stock velcro with fabric velcro and neither of our lids rattle anymore.

 

[ratz]

Did some flintstoning, some freewheeling with legs in the air, some freewheeling with feet on pedals, felt totally weird at first but soon got used to it. Then did a bit of pedalling, moved on to some turns and then pedalled along the village to an empty car park to do some figure eights. Had a few death wobbles on the way, but relax and sit up, everything was kept under control.

After about 20 minutes I was comfortable pedalling figure eights, not exactly Olympic standard elegance but good progress nevertheless. Was feeling quite pleased when I got back - and my forearms are sore! That was with me making an effort to be relaxed.

The pedal steering wasn't anywhere near as bad as I thought it was going to be. Certainly no harder than learning to ride the Fuego and most of those skills have transferred across, particularly low speed turning leaning out of the turn etc. I think because it is a fairly reclined semi-low racer a lot of the balance stuff is already drilled in. I am not worried about the learning curve though after tonight, I can relax knowing that I can definitely get comfortable on this platform.

Ding ding. that's the key;

 

[nobrakes]

Today I got the front derailleur working, had to fudge the angle and it’s not optimal but it seems to work well enough. You’d definitely be better with something that doesn’t have the yaw though, it’s designed to be much closer to the chainring than I can get it.

Ratz - will definitely be doing some rattle dampening. Went out again tonight with the lid off and it still rattles, so more investigation needed.

Second run tonight was a little better, more turning / figure eights for 20 minutes and then out the village into the pitch black to do a couple of miles of rollers with the lights on. It’s amazing how much easier it is to honk up hills, I can feel it in my abs now. Great to not have to gear right down and spin.

I’m very much impressed so far, looking forward to getting enough skill to do some proper runs.

 

[ratz]

Today I got the front derailleur working, had to fudge the angle and it’s not optimal but it seems to work well enough. You’d definitely be better with something that doesn’t have the yaw though, it’s designed to be much closer to the chainring than I can get it.

Thoughts on the FD

You might want to search the forum on yaw and check out some of the videos we've posted. A few of us had to re-learn how to do yaw versus traditional and then it's a piece of cake. To date I've personal done a ton of V20/S30's with wire pull yaw and they have all worked just fine. It makes me think you might have MTB spacers on your BB Cups or if you have the old chain stay it's mount off center. Last possibility is the triangle is not square. Something has to be wrong or we'd have heard more of this by now.

So square the triangle you have to loose everything after marking the positions with tape then tighten them back up in this order: QR Wheel skewer; BB Clamps, Boom/Slider length clamp; and last the Pivot clamp. That will square it up and might just fix you FD problems.

 

[nobrakes]

I’ll check that ratz, but I think the problem is just that the FD is too far away from the chainring which puts the whole thing in a suboptimal position because the yaw is designed to work with the FD 1-2 mm away. I can see it would work perfectly if the FD was closer. I can’t get it closer though because the braze on mount doesn’t have enough adjustability for my 50T chainring.

 

[ratz]

I’ll check that ratz, but I think the problem is just that the FD is too far away from the chainring which puts the whole thing in a suboptimal position because the yaw is designed to work with the FD 1-2 mm away. I can see it would work perfectly if the FD was closer. I can’t get it closer though because the braze on mount doesn’t have enough adjustability for my 50T chainring.

Understood but that shouldn't be true unless your q-factor is wide right. Got photos of the nose of the bike? Did you put a spacer between the BB-shell and the BB-Cup? It's worth asking if we can get it sorted out for you.

 

[nobrakes]

I'm not sure I understand - Q-Factor is the crosswise width between the cranks, is that correct? The BB did have spacers but I took them off when I put the BB in (first attempt with spacers on and the bb locked itself up when I tightened it down lol). The distance I am talking about is the lengthwise distance along the bike between the FD and the chainring, not the crosswise distance. Maybe I am not understanding what you mean though. Here's a picture of the FD / chainring with the FD as far forward as it goes on the mount to show what I mean - I can't push it closer to the chainring as per the Sram documentation.

If you install the FD so that it is vertical in the mount, the yaw design means that it doesn't push the chain up onto the big chainring properly because of the slant of the shifter, as the part of the shifter pushing the chain is too far down and is therefore further away from the chainring. You can't adjust the FD to be further towards the big chainring, as then the top of the FD snags on the chain. I got round this by rotating the entire FD towards the cranks (i.e. pulling the bottom of the FD round until it is just about hitting the right crank) which means there is lesss 'yaw' on the derailleur and it pushes the chain further without interference on the chainring. It does work although there is very tight clearance between the FD and the crank. When I said this was suboptimal I meant that it's not really using the yaw feature as I have had to rotate the FD to make it more 'vertical' as per a standard FD. I can see that the yaw would work perfectly if the FD was closer to the chainring. If I had a larger chainring I don't think this would have even been an issue.

I can't post a picture of the nose of the bike just now as I'm in the office but can do one later if you think I've still got the wrong end of the stick.

Cheers

 

[ratz]

FD as far forward as it goes on the mount to show what I mean

I still think of that as "down" not forward



Now I under understand. it looks like you are getting bit by the length of your boom; and the way the stalk rotated.

There's a shim from Rotor; I'll look the part number up. You put it on the derraillur and will let you shift it that last little bit; it's designed to solve that exact sort of conflict with Qrings. (They also make one that push the derailluer rear ward that solve the problem too although that second solution makes it a touch trickier to tune the first time.

 

[nobrakes]

Thanks ratz, appreciate the help. It does work as-is, possibly not as smoothly as it should though.

 

[Jeremy S]

it looks like you are getting bit by the length of your boom; and the way the stalk rotated

Don't think that matters here, the stalk is designed to fix the geometry regardless of boom length/rotation. On my Silvio 2.0 a 50t works fine. Seems like Cruzbike changed the spec on the stalk on recent models.

 

[nobrakes]

Don't think that matters here, the stalk is designed to fix the geometry regardless of boom length/rotation. On my Silvio 2.0 a 50t works fine. Seems like Cruzbike changed the spec on the stalk on recent models.

Are you running an sram yaw derailleur too Jeremy?

 

[ratz]

Don't think that matters here, the stalk is designed to fix the geometry regardless of boom length/rotation. On my Silvio 2.0 a 50t works fine. Seems like Cruzbike changed the spec on the stalk on recent models.

I would have thought it should be the same, maybe not. My point of reference is the RAMM bikes and we didn't have that problem on them all the ETAP stuff is YAW too; those were 50 QLX and the reach was good even on the middle diameters....; but granted they aren't Force 22. I do have a Force in the basement but it's on a bigger ring so I can't compare. On the winter list I guess as it would be good to know.

 

[dtseng]

(1) file the lower slot edge 2 or 3 mm; (2) if there is space on FD, drill and tap a hole higher.

 

[Jeremy S]

Are you running an sram yaw derailleur too Jeremy?

Looks like I got my details wrong. I have a Rival 22 (Yaw) FD now, but with a 50t Q ring which has variable radius and is wider than a standard round ring at its peak. Its clearance is fine but the derailleur is near or at the bottom of the adjustment range on the stalk. Back when I had round rings, I had an older (non-Yaw) Rival FD which has two mounting holes, and I was using the hole that put the derailleur closest to the chainring.

 

[Jeremy S]

I have no personal experience with this product, but maybe worth a look:

https://www.artscyclery.com/SRAM_Braze-On_Front_Derailleur_Shim/descpage-SRFDSH.html

 

[dtseng]

I think this is a factory QC problem. The hanger post is welded on the chain stay too high and slanted too much to the back.