Need more clearance btw deraileur and ground

[Rick Mason]

Hey Yakers,

I'm looking for ways to gain more clearance between my rear derailleur and the ground.

I have a new NWT - 18 speed / two ring.  It came with the microSHIFT M46S MarvoLT Short Cage rear derailleur, an 11-34 cassette, 53/39 chain rings, and 1.35 (35mm) wide tires. When in the Lowest gear (39/34) the bottom of the derailleur cage is less than an inch from the ground, and less than 1/2 an inch from the side of the tire. In this condition, there is no way I would want to ride on anything rougher than light gravel.

For reference, the NWT this bike is replacing, has a Shimano Deore rear derailleur, 52/42/30 triple, and an 11-28 cassette. The bottom of the cage on that bike has plenty of clearance to the ground, and is above the tire, so has clearance there to.

I'm looking for ideas for how to deal with this.  My ideas are:

1) Buy a new derailleur (suggestions welcome).

2) Shorten the chain - I think it may be too long anyway as the shifting at the extreme ends (both between the 28 and 34 cogs, and the 11 and 13 tooth cogs) is pretty poor.

3) Swap the triple on my old bike with the double on the new one, and reduce the large cog to 28 (could even swap the entire drive trains...)

4) Something else??

The MicroSHIFT website doesn't list the arm length under specs, but my measurements put the length at 97 mm vs 102 on the Deore (measured center to center between the jockey and tension pulleys), Not sure, but that would seem to suggest that the it has a short cage.

Thoughts?

Do any of you have a newish bike configured with this derailleur/cassette combination, and if so, what do you measure as cage length?  Note that this is the basic design.

Thanks

[Paul Webb]

Hi Rick,

Assuming the old NWT has 9 or fewer cogs on the cassette, the Deore RD from your old NWT should work fine with the MicroShift shifters on the new bike.  It's a fairly quick experiment.

Paul

[Wolfgang Ketterle]

Your derailleur cages are rather on the long side.  I have an 105 GS (medium cage) and a vintage long-cage Deore XT which both have a length (center to center of pulleys) of 87 mm.
They should have enough capacity for your application and should give you more ground clearance than your 97 or 102 mm cages.

For a Brompton (with 16" tires), I have just mounted a Deore XT short cage (with a length of 69 mm).  But here I had to modify the cage to get enough capacity:
see
https://www.facebook.com/groups/796190400521866/posts/3135315776609305/?__cft__[0]=AZVRSXMnqIfrcS7xvu3fuRsMIpuLMQh4D_YG8k0PxJ7M5LQv5RB8hL0WEjIUN71vuqj9UqR-Z0jX7ge0TV80ZbQqmylFZWPRT6ILfkRUCSBnAqdWfJBl4NvYaIRL7-Tvt4WZr_FbM-e64g0tNggi6h5ZCIgIM_n5-28n-sq9n7Nw5rwgfHDrpeSRGhSQuTaUZ_0&__tn__=%2CO%2CP-R

On a Tikit, I now have 11-36 10-speed with a Shimano Zee derailleur which has an ultrashort cage length of 50 mm.  Works great with a single chainring, and has excellent ground clearance.  But it doesn't have the capacity for a double chainring.

--
another great conversation from the Bike Friday Yak!
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[robert clark]

Long ago (& the company since has closed but..) Sun Tour Used to make a 3 pulley rear derailleur 

the chain took a long route over 2 lower pulleys  to wrap up chain slack differences.. rather than a long cage..

You can probably find pictures on the internet,  then  seek a person to replicate something  like it..

 I bought a Rohloff hub Llama , had i gotten a  newer NWT Silk,

 I could have even done without the short cage chain tensioner..

[robert clark]

An internally geared crankset has 2 or 3 speeds but 1 chainring  

Schlumpf  has a reduction gear  & 2 overdrive  gear models, 

Efneo GTRO has a  3 speeds with 2 overdriven ratios ,,

the  gears between the crank spindle & the chain ring allows them to turn at different rates

overdrive the chainring turns faster-more often than the pedals 

a reduction gear the pedals turn faster than the chainring.

yea they're heavier than physical aluminum chainrings..

[Rick Mason]

Thanks all,

I should add that I would like to keep costs as low as possible, so internal hubs or bottom bracket solutions are probably too spendy.

I do like the mid length cage idea - I can get a 9 speed medium cage Sora rear derailleur for a reasonable price. It works with a 34 tooth max cog, and 16 tooth max front difference, so it should match my gears.

I think doing that will work. If I shorten the chain a bit, the derailleur arm should be at a forward angle when in the 34 tooth.  I'll give that a try. Not free, but reasonable. I expect to gain 1/2 to 1 inch of extra clearance.

As for poor shifting, I read on a review for another bike using a cheap cassette that it had inconsistently spaced cogs, resulting in poor shifting, and "hunting" between gears at the far ends of the cassette. That's exactly what I see with the standard Sunrace cassette, so perhaps replacing it with something better will help.

None the less, I'm unclear why Green Gear specifies the NWT with a derailleur so close to the ground.

[Wolfgang Ketterle]

Another possible cause for poor shifting can be a bent derailleur hanger.

[Rick]

True. I do have the Park tool to measure / fix that. I'll definitely check it.

------ Original Message ------

From "Wolfgang Ketterle" <kett...@mit.edu>

To "Rick Mason" <rick.a...@gmail.com>; "Bike Friday Yak!" <y...@bikefriday.com>

Cc "ro3ert...@gmail.com" <ro3ert...@gmail.com>

Date 7/7/2023 4:41:24 PM

Subject Re: [yak] Re: Need more clearance btw deraileur and ground

[John Thurston]

Check the alignment of the derailleur hanger. The symptom you describe can be explained by the axis of the derailleur-pivot not being parallel to axis of the wheel.

On 7/7/2023 2:34 PM, Rick Mason wrote:

As for poor shifting, I read on a review for another bike using a cheap cassette that it had inconsistently spaced cogs, resulting in poor shifting, and "hunting" between gears at the far ends of the cassette.

-- 
John Thurston
Juneau, Alaska

[Stephen Turk]

If the poor shifting is only in one direction (i.e., from 28 to 34, from 13 to 11) then you should check your limit screws. If it's generally poor in both directions, that's probably not the problem.

Stephen Turk

SteveT...@gmail.com

(213) 300-4149

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[Rick Mason]

Lots of good suggestions - Check hanger for alignment, limit screws. etc. I'll look at this to see. I did some of this already, but it doesn't hurt to double check. I also tweaked the "B" adjustment. That definitely helped on the low (large cog) end.

My initial concern was to get more clearance to the ground, and the most consistent message is to get a shorter arm dérailleur - ideally a mid length model.

I'll get this puppy dialed in yet!

[Geof Gee]

On Wed, Jul 5, 2023 at 2:40 PM Rick Mason <rick.a...@gmail.com> wrote:

Hey Yakers,

I'm looking for ways to gain more clearance between my rear derailleur and the ground.

I have a new NWT - 18 speed / two ring.  It came with the microSHIFT M46S MarvoLT Short Cage rear derailleur, an 11-34 cassette, 53/39 chain rings, and 1.35 (35mm) wide tires. When in the Lowest gear (39/34) the bottom of the derailleur cage is less than an inch from the ground, and less than 1/2 an inch from the side of the tire. In this condition, there is no way I would want to ride on anything rougher than light gravel.

For reference, the NWT this bike is replacing, has a Shimano Deore rear derailleur, 52/42/30 triple, and an 11-28 cassette. The bottom of the cage on that bike has plenty of clearance to the ground, and is above the tire, so has clearance there to.

Lots of good suggestions including your own idea of the amount of chain. 

I'll add that you can use wider tires which also have more height. So if you go from 35 mm to 45 mm tires, the derailer should be roughly another cm higher off the ground.  

-G

Arlington, VA 

--

"Sometimes I forget things.  Who I am.  Where I am.  Unimportant things. But I'm not insane. "

[Paul Webb]

It's something to look at, but the wider tyre might work against you too!  ;-)  

I've been more concerned about tyre clearance then ground clearance.

Paul

On Wednesday, 12 July 2023 at 09:42:16 UTC+10 geo...@gmail.com wrote:

On Wed, Jul 5, 2023 at 2:40 PM Rick Mason <rick.a...@gmail.com> wrote:

I'm looking for ways to gain more clearance between my rear derailleur and the ground.

I have a new NWT - 18 speed / two ring.  It came with the microSHIFT M46S MarvoLT Short Cage rear derailleur, an 11-34 cassette, 53/39 chain rings, and 1.35 (35mm) wide tires. When in the Lowest gear (39/34) the bottom of the derailleur cage is less than an inch from the ground, and less than 1/2 an inch from the side of the tire. In this condition, there is no way I would want to ride on anything rougher than light gravel.

[John Thurston]

Clearance in the frame is one thing. But one also needs to watch clearance between the tyre and the chain.

With a smooth-wall tire (like the tioga powerblock), the chain getting bounced over against the tire isn't a show stopper. But if that tire is (for example) a fat knobie, then a knob can catch and foul the chain. (ask me how I know)

On 7/12/2023 5:53 PM, Paul Webb wrote:

I've been more concerned about tyre clearance then ground clearance.

-- 
John Thurston
Juneau, Alaska

[Rick Mason]

I left this thread with lots of suggestions, but may have left the impression that I didn't or wasn't going to do anything with them. So it's time for an update, and to tell you what I have actually have done.

The main thing was to replace the Microshift Marvo Long cage deraileur that came stock on the bike, with a MicroShift R9 medium cage. The R9 is basically the road equivalent of the Marvo, and is the matching rear derailleur to the R9 front derailleur that came on the bike. The Marvo allows a large cog of 28 to 36 teeth. The bike comes with an 11-34 cassette. Going to a 36 large cog would REALLY be pushing the bottom pulley too low, so realistically, 34 is as big as will fit. The Marvo also has a total capacity of 45 teeth. Given my 11-34 cassette (25 diff), and 53-39 crankset (14 diff), I have a total wrap need of 39 teeth. The R9 can wrap up to 39 teeth, so it meets the required wrap, even if barely.

I can already hear some of you saying that I should pick a derailleur with more capacity than I need, but in my experience, manufacturers tend to be conservative on their "max" ratings, so I wasn't worried about bumping up to the limits, and what I've found in the 100+ miles I have ridden this set up, this derailleur works just fine.

Now the good part. If you look at the pictures I have included, you will see:

First, just how close the Marvo comes to the ground. While I didn’t include a picture of the clearance to the tire, it’s less than ½ of an inch. The present tires are 35 mm wide. If I want to do gravel, I'd likely look to use something close to the max the frame is capable of - 1.95 inches / 50 mm. If I do that, I'm looking at 15 mm wider tires, or 7 mm / 0.3 inches less clearance on each side - pretty much all the clearance available with the Marvo.

Old derailleur - nearly touching the ground! Also note the angle of the derailleur, and compare it to the new derailleur below. 

And no, I haven't scratched the derailleur up, it's just dirty for riding across puddles from all the rain we've received lately.

Close up of the clearance to the ground

Second, looking at the picture of the two derailleurs side by side, you can see the difference between the cages length. It's about an inch! On top of that, the Marvo derailleur body hangs almost straight down, where as the R9's hangs at about a 45 degree angle.

Third are pictures after changing the derailleur. You can see that there is *A LOT* more clearance to the ground - about an inch more, and the bottom of the cage is even with the rim, not the tire, so if go to a larger tire, I should still have the same clearance I have now.

Clearance to ground with the new derailleur. Also note the 45* angle the body has.

Close up of the new clearance. Note that the cage is now above the tire.

Not a great picture, but you can see the clearance to the tire. And from above, with the cage above the tire, I should have no issues fitting fatter tires.

-------------------

I expected to need to significantly shorten the chain, but found that removing 1 link balanced the needs between the two worst case cross chained limits. Bottom line, the clearance issues are solved.

In the end, I'm probably more concerned than I need to be, but I'd rather be safe than sorry. So thank all of you for your input!

Hopefully, this is / will be useful to future readers thinking of buying a new NWT, as something to consider.

The other part I raised in this thread was shifting issues. I received some other good input on that as well. I used my measuring / adjusting tool (Park DAG-2.2 Derailleur Hanger Alignment Gauge) when the derailleur was off, and found a small amount of error. Not much, but enough that I tweaked it a bit. Whether that was enough deviation to be the cause I don't know, as I'm still working on getting the shifting perfect, but at least works well enough to use all gears now, I just have to slightly over shift going to larger cogs, but that's pretty minor.

So, there you have it.

[Kristi DuBois]

I have been following this string of posts. This all seems a bit odd to me, as my NWT, ordered this spring came with the Microshift R9 on the rear. I wonder if they had trouble getting them in when you ordered your bike? Looks like you now have the same drive train setup as mine. Too bad you had to go through all of this to get it. Let's hope it works well for us.

I have mostly ridden mine on the pavement, but am hoping to ride it on gravel roads as well. I hope to replace my 1.75 wide Marathon tires with wider tires with a little more traction at some point. Let us know what fatter tires you end up getting for yours.

Kristi

Missoula, MT

[Rick Mason]

Thanks Kristi. 

That does seem odd that your bike has the R9, which it looks like mine should have. I had wondered why Bike Friday would use a derailleur that hung so low. Maybe they did have trouble getting the R9, though I found several places that did have it in stock.

I did find a few other anomalies as well - The cable to the front derailleur was routed over the under bottom bracket guide instead of through it (simple fix), as well as the shifting issues that I had out of the box.

I haven't decided on fatter tires, but yes, I'll post that, as well as a link to a review I will likely put on my personal web site.  When I do use bigger tires, I may even build a second set of wheels, probably with a tighter cassette for more aggressive (read club rides) times.

Rick

[robert clark]

Long ago the Sun Tour company made a 3 pulley derailleur 

kind of triangular,

2 on the bottom, to take up the slack made an equivalent

long way around   for the chain slack take-up, without sticking down so far..

I was Younger , Too...

[chintan jadwani]

Microshift has a super short cage Advent derailleur now that goes up to 38t with enough clearance - https://www.microshift.com/models/rd-m6195s/

The issue is that there is no cross-compatibility with Advent and Shimano and one would need a new cassette, shifter, and RD.

[John Thurston]

The RD-M6195S is an interesting product, with some interesting limitations:

• It can handle a 38t large cog, but is rated only for an 11t small cog.
• It only works with "Advent" trigger shifters
• The Advent shifters are 9-speed
• Can absorb 27t of chain
  

So if you are running flat bars, can live with 9 gears, and accept an 11t small cog, then it's worth looking at.

There are probably other shifters which can be made to control it, but its cage will have been designed to handle a 9-speed chain. Making it control a 10 or 11-speed chain is going to require a lot of hacking.

On 8/29/2023 1:26 AM, chintan jadwani wrote:

Microshift has a super short cage Advent derailleur now that goes up to 38t with enough clearance - https://www.microshift.com/models/rd-m6195s/

The issue is that there is no cross-compatibility with Advent and Shimano and one would need a new cassette, shifter, and RD.

-- 
John Thurston
Juneau, Alaska

[Rick Mason]

Keep in mind that I have a double chain set. So my required total "absorption" is 37 teeth (53-39 + 34-11). That's 10 teeth less than the RD-M6195S can handle.

[robert clark]

I see the pivot in the cage  has been  moved  lower, in between the 2 pulleys  to let top pulley move forward more as the lower one moves back.  

where others the pivot is nearer or concentric with the upper pulley.. 

FWIW Old <C> record  were only 45mm between the pulleys,

Pivot 25mm from & A bit ahead of the top pulley about 20 from a point equidistant  between the pulleys..

[robert clark]

they were expecting 10t  difference in chainrings t count   & for 13-26t cog differences