Vamoots RSL 44mm Headtube

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Vamoots RSL 44mm Headtube

26 posts from 10 voices

Started 1 year ago by wrpercival
Latest reply from tjwall78

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wrpercival
Member

I am considering purchasing a Vamoots RSL and would like to know more about how a 44mm head tube impacts the handling and performance of the bike.

For example, does it most benefit heavier riders, or strong sprinters due to stiffening of the triangle? Alternatively, is the primary impact increased stability in the frame/fork connection that benefits handling - say on rougher roads, or high speed descents?

If the larger head tube primarily benefits heavier riders, at what weight should a rider consider including it in their build over the standard head tube?

If it adds any context to my questions, I enjoy riding aggressively and being able to push a bike hard with confidence. I'm on a 56cm frame and weigh 180 lbs - all muscle of course. :-)

Thanks in advance for the input & perspective.

Posted 1 year ago #
teamfubar
Member

I'm sure Jon will chime in here soon, but the 44mm head tube would offer a few advantages. First, the ability to run a tapered steerer tube on your fork, increasing stiffness and control. Second, the larger diameter would offer a better surface area to weld the main triangle tubes to, while being able to get the tubes closer to the edges of the headtube. Third, with the "inset" headsets, a lower stack height, keeping the geometry on target with what Moots intended.

I wouldn't think there is much downside to the 44, no matter what the size of the rider is.

Posted 1 year ago #
Mikej
Member

Actually, you would need to get custom geometry to run the 1.5" taper. Otherwise your head tube would be up higher.

Posted 1 year ago #
wrpercival
Member

Thanks @team/@mike for the info.

In the event you use the larger head tube, does Moots have a tapered version of their fork, or will you need to use a third-party (tapered) fork to take full advantage of the larger size?

Thanks again.

Posted 1 year ago #
JonC
Administrator

All,
Thanks for chiming in....As stated above there are many benefits to the larger 44mm head tube. To sum up some:

--top tube and down tube can present a bigger footpring onto the head tube.....no need to ovalize them at the ends...stiffer, stronger...
--tt & dt can be held closer to the edge of the ht...wider stance
--you can run a tapered fork if you desire (however, custom geometry must be ordered so you will not upset the handling of the bike as stock), ....
--Even in the non-tapered fork setting this feature adds to overall stiffness no matter your body weight.

No, we don't offer our new fork in a 1.5 tapered set up....we had to start somewhere and the standard 1 1/8'' was it for now.

Let me know if you have any other questions...

Thanks!

Jon@Moots

Posted 1 year ago #
wrpercival
Member

Thanks Jon and others. I really appreciate the information.

Posted 1 year ago #
wrpercival
Member

Jon - sorry - one more question.

I went to King's website and I looked at the head set solutions they offered for a 44mm head tube.

It looks like if you select a tapered fork, the head tube length will have to be shortened to maintain target geometries. I that's true, in your opinion, what's the better option - go with a tapered fork, shorten the head tube (thereby decreasing the distance between the TT and BT), or go with the 1 1/8 fork to maximize the length of the head tube.

My apologies if I am getting a bit specific (read: anal), but I like understanding the evaluation process.

R/

Bill

Posted 1 year ago #
davidb
Member

Keep the technical stuff flowing. It's captivating.

Posted 1 year ago #
ROO
Member

Today was my day...I pulled the trigger on a Vamoots RSL!!!

As part of my VERY long decision process, I went throught the same questioning - here's what I found:

A standard 44 HT with the external bearing will raise the HT and change the HT angle by 0.5 degrees. Two ways to go, full custom up charge on the frame or use a 43 degree rake fork (assuming your frame size is standard with a 45 degree) which will effectively compensate for the HT angle change (almost). You'll be really close but still a little higher. Custom will allow you to keep, or change, the HT length to what works best for you.

ENVE, for example, only makes a 43 degree tapered fork.

I went custom to get the frame spot on for the HT angle and for a few other tweaks...now the waiting game begins!

Posted 1 year ago #
JonC
Administrator

If going with the external 1.5'' lower bearing and tapered fork set up, it's best to go custom. .5 degrees is noticable on the road, while you can get close by not going custom, it's still only that...close but still not the geometry we are looking for.

I hope that makes sense.

Thanks,

Jon@Moots

Posted 1 year ago #
nstilwell
Member

Not trying to hi-jack this thread, but I have a similar question for the MXYBB
(Jon - feel free to move to a new topic if warranted)

I'm under the impression you have two headset options for the MXYBB when getting the stock 44mm headtube.

1) Fully inset headset to use a straight 1-1/8" fork (King Inset 1), or
2) "mixed" inset with the external bearings at the bottom to use a 1.5" tapered fork (King Inset 7)

Is this true or will the latter option raise the front end and upset the geometry. I wouldn't think it would on a mountain bike, but thought I should ask the question.

Posted 1 year ago #
tjwall78
Member

nstilwell- You are correct, those are the 2 headset options for any 44mm head tube from king. And yes going with an external lower baring well raise the front end, about 10mm, and slack the HT angle about .5° slowing your handling.

wrpercival- I ordered a RSL about 4 weeks ago and went through a similar process. I went with a 44mm HT and enve tapered fork for a few reasons. One was for stiffness and handling; the other reason was b/c a Moots is a life time bike and the market is moving towards a tapered fork (I was worried that a tapered fork would be all that is available at the high end of the market in a few years). The RSL geo is for a 1" 1/8 fork; if you want to go 1.5 taper go custom spend the extra money. If you're spending the cash for a RSL make it perfect not just close. I also added length to the HT, b/c you lose about 12mm stack height from the standard 1"1/8 external king headset and I did not want to run the extra spacers need to make up that height (It would not change handling I just don't like the look of a ton of spacers).

Hopefully Santa will bring my bike for Christmas.

Posted 1 year ago #
egordon
Member

Does the custom geo also apply in running a tapered for in the Mtn RSL?

Posted 1 year ago #
ROO
Member

tjwall78-

I agree 100% with going custom with the tapered fork. I just went custom on a RSL too and was told the if you go with a 44 HT option MOOTS adds ~20mm to compensate for the lack of external headset (Chris King in this case). I'm still waiting for my CAD drawing so I might be off and also have to add some length to the HT. Either way I thought I'd put it out there. Can anyone clarify?

Also, any suggestions/option to add if I'm going custom? I'm going with the 44 HT, slightly shorter TT, possibly larger DT. Any other thoughts?

Thxs

Posted 1 year ago #
wrpercival
Member

tjwall78 - Thanks for the info & (long term) perspective.

Originally I had thought that introducing a tapered fork would increase the overall stack height, necessitating a reduction in the head tube length to maintain the standard geometry, and that would correspondingly reduce the main triangle stiffness resultant from the decrease in spread between the top tube and down tube.

If I understand your explanation correctly, you actually need to lengthen the head tube to maintain the target geometry and, based on Jon's earlier response, that should beneficially maintain, or increase main triangle strength. Therefore, the integration of a tapered fork actually results in a stronger triangle, stronger frame fork connection - a win/win. Excellent.

That's what I really wanted to understand. In pursuing the head tube question/evaluation, I did not want to sound indifferent to the added cost of customizing the build but, like you, I fundamentally believe it is worth "getting it right", particularly in the long run. Your perspective on future compatibility is also good.

Two questions: Do you know if it is possible to have Moot's paint a custom fork to match the frame, or alternatively, to get the paint specs and have a third party finish it. Also, I noticed from one of your posts (mid November) that you had spec'd a threaded BB versus a PF. Can you tell me why you chose threaded versus PF?

Thanks again for the info. Hope your frame arrives soon.

Posted 1 year ago #
JonC
Administrator

ergon,
Not so much on the MX RSL as there are more variables to be messed with, such as sag....Putting just a touch more sag into the 100mm fork on the RSL can get you pretty close to the intended geometry....if sitting with no weight on the bike, yes it will measure slack, but once you sag the fork with rider weight and move through the travel it's not too far off....some even like the touch slacker set up depending on your riding style.

Thanks,

Jon@Moots

Posted 1 year ago #
tjwall78
Member

wrpercival-

The correct geo is maintained by changing the HT angle when going with a tapered fork. I added heigth to the HT to compensate for the loss of height that comes from going with and interal instead of a external upper bearing. I also added a little to the seat tube.

I chose a 68 threaded BB over BB30 for a few reasons.
1. I like shimano and that is currently the best option for a shimano crankset (moots does not offer bb86).
2. Easier maintanance and less reports of creaking problems.
3. I like the larger contact surface area that a threaded bb offers.
4. The idea that i will flex a 68 mm wide ti tube with a diameter of 30mm and 4 other tubes welded to it is silly. Its the diameter of the chain stays and down tube that provide most of the added stiffness.
5. The idea that i will flex a 68 mm BB tube and not compress the nilon sleeve of a pf bb30 is even sillyer.
6. With a lot of the larger companies moving to the longer BB86, BB90, BB92, BB95 ect i feel that is the way the market is moving. Not all of these types of BB's will survive 5 years from now and i think the movement is to a wider and longer BB, and a standerd 24 mm spindle is convertable to most of these types while a bb 30 crankset is not.

This is just my bias and speculation and i could be way off. The bottom line is i just trust the 68 mm threaded bb more.

Posted 1 year ago #
wrpercival
Member

tjwall78 - Thanks for the response/info. Appreciate the detail.

Posted 1 year ago #
Mojo Man
Member

wrpercival,

I totally agree with you. I’m not sure why Moots has opted to use this on most of their newer designs. The extra stress of the narrow bearing placement concerns me.

Now if they were mounted out board or the BB was wider, then I could see considering this route.

Just my $.02

Mojo

Posted 1 year ago #
tjwall78
Member

The inner diameter of a english 68mm bb is 33.8mm not 30mm. Sorry for the error.

While I went with the english threaded 68mm bb, it was not a easy descision. PF 30 has advantages as well.

1. Lighter frame and crank set.
2. Less machining of the seat tube and down tube.

Weight was not my primary concern. My rigor has a 68mm engilsh bb and a 35mm ST (and i believe a similar diameter down tube) and the machine work on those tubes are a work of art so i have faith in moots machining ability. That coupled with my reasons stated above was why i when with a english threaded bb.

Posted 1 year ago #
JonC
Administrator

Gents,

There are a couple more reasons we went with the PFBB30 route on our road, mountain and cross offerings...let me explain:

PFbb30 allows the use of the larger diameter bearing of course....along with this you get to use the larger diameter crank spindle, that is: stiffer, lighter and has a narrower Q-factor. Remember Q factor? Yes, it's a good thing to have the option of not running outboard bearings along with wider and wider crank systems that make you feel like you've mounted a saddle on a horse. While it's not that drastic, it does factor in.

We also us the PFbb30 because it isolates the bearing from the metal shell. Our initial prototypes used the standard BB30, where the bearings pressed directly into the shell, which gave us metal on metal contact...in this case stainless steel on ti.....you want to talk about creaking! No lube/paste/anti-seize can stop that issue.

Diameter....We also choose PFBB30 for its large outside diameter, which allows us to use bigger diameter down tubes, seat tubes and chain stays and not have to ovalize the tube to make them fit.... Foot-print is king when you want to increase stiffness and by using the PFbb30 shell, we are able to keep the tubes large, thus increasing the stiffness of the drive line.

PFBB30 is easy to maintain, has a good life span and if and when you need to replace it, won’t break the bank either. My testing ground has been the Psychlo X RSL that I've ridden and raced for over a year...power washers and ugly mud races...yes, I've gone through some bearings, but most any bearing out there will not hold up to that...

Yes, there are many bb's coming into the market, not all of them are perfect and it will take some time to sort out exactly what will stick and what will not....but in the end we felt the PFBB30 to be our best avenue to accomplish our goals with the RSL family. Stiff, light and durable, while maintaining the Moots build quality we are known for.

I’m biased, yes…I live, work and breath Moots…but I’m also one of the first to be skeptical of changes to our bikes without reason, and trust me when I say, we have good reason to build like we do…..also, after spending over a year and a half going back and forth on a PFBB30 to standard English thread bb, I can say I’m a convert….

That's my .2

Thanks,

Jon@Moots

Posted 1 year ago #
Mojo Man
Member

Sorry wrpercival,

I ment to refer my reply to tjwall78

I like technology as much as the next guy and improvements also, but I'm having a tough time seeing it with this PF30

Mojo

Posted 1 year ago #
tjwall78
Member

I agree with JonC 100% that PF30 is the best option going if weigth is one of your main goals. And for most people going with the RSL line a perfect fit. It seems that the creaking issues noted here before have been worked out, so i can take that off my list of reasons i went with a english 68 BB. That fact that Moots has it as a option is ironically one of the reasons i will ALWAYS go with Moots. I love how they research new technologies and incorprate ones that have benefit, and PF 30 has a pretty big weight benefit. I also love how they keep it ti only!!!!!!!!!!!!

I do have a question about q factor. Q factor is as much about the angle of your crank arm as it is about spindle length. It's been awhile, but i've measured sram red bb30, DA 7800, and Ultrgra 6600 and i believe all of them came out at about 145-147mm at the threads for the pedal spinle; pretty close.

The aluminum spindle is definatly lighter but how much stiffer. Steel has a much high younger molecule number; making it inherently a stiffer/denser metal (given the same diameter/thickness tube). I don't know for sure that adding 6mm to the diameter would make up that differance (i'm sure there is a equation for that); i think it would but by how much. Plus the spindle only sticks out about 20mm past the bearings, i doubt i would be able to flex either with that being my lever arm.

PF30 is a good option that does have some clear benefits, most notability weight. It just was not for me, but like i said before i'm bias and have very little experience with PF30. I like how Moots has this and other options (44mm HT) added to now go across the line, and with more people goint to a 30mm spindle it was likely a nessessity.

Posted 1 year ago #
JonC
Administrator

tjwall78,
The Q factor difference from Red (GXP outboard) to Red BB30 is 5mm total...so 2.5mm on each side...not a ton, but better.

On the stiffness side the BB30 AL spindle along with the larger bearings is up around 20% stiffer. The BB30 crank also saves 130 grams at the same time...

Thanks,

Jon@Moots

Posted 1 year ago #
Mojo Man
Member

I'm going to play devils addvocate here with the PF30. Now that you guys got me thinking about them again.

What keeps the bearings and or bushings from sliding out during heavy peddle smashing? The bushings are made from nylon or delrin which both have a low coefficient of friction. So, other than the wafer/thrust washers on the crank spindle and some press force, I can't see anything else keeping them possibly from working their way out. The bearing housing doesn't have a lot of contact area either. I supose hours of testing and riding will be the final judge, which many have already done, but even so, it just doesn't make good scense to me.

Also, for the spindle stiffness rating, that's more of a funtion of the riders weight, a heavy person would see a more deflection while a weight weenie may see very little, if any.

Don't mean to argue with anyones numbers or opinions, just trying to talk my self into or out of the PF30 on my build.

Mojo

Posted 1 year ago #
tjwall78
Member

Based on my experience a 5mm differance would be very noticable, and depending on your body type beneficial.

http://pugetpower.blogspot.com/2009/10/velonews-calls-bike-industrys-bb30.html

I saw this post a while back but don't have access to the original VeloNews article so I can't speak to the validity of the numbers. I believe it also only tests the cranks and not the whole system; if that is the case it's basically useless but still intresting. Has anyone read this whole article?

Posted 1 year ago #

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