Fancy seatpost for more saddle angle adjustment?

[efair]

I'm relatively new to the bike world and I'm surprised how much there is to learn about basic bike geometry. Today's challenge is my wife's seat post on her Electra ebike. Her combination of seat tube angle, seat post design, and desired saddle angle are the issue. Her saddle adjustment is of the "two bolt" variety, with one forward and one aft bolt as shown below (this is a google image, not her seat post). In order to adjust her saddle angle to her liking I had to put a shim between the cylindrical mating surfaces in the seat post - only then could I adjust her saddle nose low enough for her. The geometry at the head of the seat post seems to be the issue:

Specifically, the angle shown in red seems to be working against me here. When I "middle" the two bolts, i.e. set the saddle angle at the center of the adjustment range, the nose of the saddle points up at a ~10 degree angle. When I fully loosen the rear bolt, and fully tighten the front bolt, i.e. set it to the extreme nose-down end of the adjustment range, the saddle is about horizontal - but she wants the nose down ever-so-slightly more. To accomplish this, I inserted an aluminum shim, and that did the trick - it added just enough additional range, that she is happy. However, I am not so happy to have a shim here - I would rather have a seat post that does not require a shim.

When reading about seat posts, I see the specifications given for length, minimum insertion, and offset, but I never see specs for the angle shown in red above. I would think, ideally, the red angle here should be complimentary to the seat tube angle on the bike - i.e. if the bike has a 57 degree seat tube, this red angle should be 33 degrees (57 + 33 = 90, the definition of "complimentary"). Maybe bikes in general don't vary in seat tube angle that much, so this just usually isn't important?

I'm wondering if anybody else has faced this, and if there are "two bolt" seat posts that might offer a larger range of adjustment than hers, or if there are other seat post designs that might accommodate a larger range of adjustment? I did try a serrated one-bolt design, which did seem to have more adjustment range, but the stepped nature didn't allow me to dial it in exactly.

I also saw somewhere a seat post that offered an eccentric bolt for the saddle angle adjustment, but I can't find it now - has anybody seen one of these before?

TIA!

 

[Base]

I was thinking of the switchgrade solution

 

[juggernaut1]

I installed the fair bicycle drop best uc saddle clamp on my eMTB. I had a different use purpose in that I wanted to move the saddle further aft (provides up to 27mm rear aft adjustment). Dropper posts generally don’t have a rearward offset like most fixed seat posts and I was on the limit of the seat rails. It can also be installed the other way to give you up to 27mm forward adjustment.

The Uc saddle clamp also has the ability for some radical saddle angle adjustments through the use of shims that can be added or removed as required. Price might be offensive to some but beautifully made piece of gear - made in Switzerland.

FAIR Bicycles DROP BEST UC Offset Saddle Clamp Review: Back and Forth – Travis Engel

The FAIR Bicycle DROP BEST UC is more than just an excuse for Travis to talk about how much he really loves steep seat angles. It can add years of life to an outdated mountain bike by moving its saddle forward by more than an inch. Or, it's a solution for people who really hate steep seat...

theradavist.com

Couple of pics on my bike.

 

[zbikeman]

FWIW, I hate these two-bolt adjusting seatpost heads. It's always a guessing game to get the right torque on both relative to whatever angle you want.

With a one-bolt standard microadjust post, sometimes a more severe angle can be achieved by turning the saddle 180 degrees, typically clamp forward instead of clamp back.

I once heard someone say it's incorrect to have the clamp forward. According to Barnett's (Bicycle Institute) manual, there is no "correct" orientation - it's whatever works.

 

[stompandgo]

I don't know what's up with her seatpost, but it's not normal. You should not need a shim. The way I adjust a two bolt seatpost to be level is to lightly snug both bolts with the saddle pointing down, then crank the rear one to level it, then snug both equally. That's for level. Adjust as necessary. No shims required.

 

[Gionnirocket]

I concur.. My current Promax seat post is the same two bolt design. I can get any angle reasonably desired.
Just follow Stompś instructions. To make small adjustments I loosen one as I tighten the other alternately

 

[Stefan Mikes]

@efair didn't you orient the seat-post clamp part the wrong way?

 

[Nvreloader]

Can't the seat post be turned 180*,
That's what I had to do, my Montague seat post.
Then adjust to fit...

 

[Chazmo]

I don't know what's up with her seatpost, but it's not normal. You should not need a shim. The way I adjust a two bolt seatpost to be level is to lightly snug both bolts with the saddle pointing down, then crank the rear one to level it, then snug both equally. That's for level. Adjust as necessary. No shims required.

Yeah, I’m not getting the “shim” thing either. I’m not quite sure what @efair is talking about. Is it shown in the picture?

FWIW, I hate these two-bolt adjusting seatpost heads. It's always a guessing game to get the right torque on both relative to whatever angle you want.

I dislike them too. Takes me quite a while to get the seat angle right. But, that’s all I’ve ever had to work with. I do like that they’re adjustable, as that’s certainly a requirement for me so I’ve never tried anything else. Maybe next time I’ll look for one of those one-bolt posts.

 

[efair]

I'm not sure this will clear anything up, and keep in mind I'm a rookie. Attached is a photo of her seat - it's currently adjusted to the "max nose down", yet as the first photo shows, her seat remains relatively near to horizontal. On two other bikes I've looked at, adjusting to "max nose down" results in a visibly less horizontal seat.

In the second photo, you can see the forward adjusting bolt circled and protruding from the top of the clamp (as you would expect for "max nose down"). I also highlighted two angles - red and blue - the blue angle shows that the clamp is oriented at nearly 90 degrees to the post, and the red angle shows the angle between the seat post and the seat rails.

The yellow arc is where I inserted the shim.

Back to my original point of confusion: Seat posts comes with a clamp on top, and that clamp is set at an angle relative to the seat post. For example, this clamp is at nearly 90 degrees to the post:

Whereas this clamp is at probably 70-75 degrees to the post:

I believe the issue with my wife's seat is that this clamp-to-post angle is wrong for her bike - it's too close to 90 degrees, and she would be better served with a post closer to 70-75 degrees.

Now back to my original question: Why is it that seat post manufacturers don't advertise this angle between the clamp and the post? It seems, at least in my wife's case, to be significant.

To understand how the shim helps, imagine sitting by yourself on a see-saw (a.k.a. teeter-totter), your end of the see-saw will be on the ground, and the see-saw would be at a certain angle relative to the ground. Imagine you needed to increase that angle oh-so-slightly, what could you do? 1) shorten the length of the see-saw, or 2) raise the fulcrum of the see-saw slightly higher above the ground. Transferring that logic to the seat post clamp, the only practical option is # 2, and that is the exact purpose of using a shim.

 

[stompandgo]

It's not normal to ride with a saddle pointing 20 degrees downward. What is she trying to accomplish by doing that? She may be better off with a saddle that has a large cutout, or a dual nose saddle like an ISM.

 

[efair]

She doesn't want 20 degrees downward, not sure how I implied that. Her complaint, all along, was the nose of her saddle was too high. Saddle height was ok, setback was ok, just the nose was too high. Lets re-frame the discussion: In the photo above, her saddle is nearly horizontal, and it required every bit of adjustment, plus a small shim, to achieve that. Why? Because of the combination of 1) her seat tube angle, 2) the geometry of her seat post, and 3) the adjustment range of her saddle clamp.

I think the solution (duh) is to find a seatpost with either a different geometry or a larger adjustment range. I can't see any other solution. And I don't see these attributes quantified anywhere in any product literature.

I'll figure this out eventually, via trial and error I suppose, but a more technical approach would be nice.

 

[Base]

saddle needs to able to be mounted horizontally.

In this case a traditional "canlde"style seatpost would be used with a traditional saddle clip.

the range of movement is more than with the newer styled seatposts.

Besides this, the dual bolt version do withstand the EN tests, the single bolt versions all fail under stress test, so I am more fan of the dual bolt versions.

The picture above is rather standard on traditional dutch bikes.

 

[stompandgo]

We sell and rent Electra Townies at the shop all day long. No issues getting the saddle level or slightly downward, or complaints about saddle positioning. Is the saddle OEM? Is the seatpost OEM? If so, do you have it facing the wrong way? If everything is OEM and properly installed, then the problem is not the seatpost, it's the saddle fit, or bike fit, to the rider.

Why does she want the nose of her saddle lower? Is she getting pressure in her private area? If so, there are a number of possibilities. I see two things from your photos. First, the saddle is pushed all the way back to the end of the rails. Why? Second, that saddle has a high tail angle and a wide nose. That kind of saddle can push the rider forward onto the nose if not in the right place for the rider. My suggestion would be to try moving the saddle forward 1cm and try it for a few rides. That should rotate her hips back a bit. To go any further, I'd have to see more.

To answer your original question, there are a number of two bolt seatposts that allow a wide arc of adjustment. They use a solid post with a two piece clamp.

 

[efair]

The saddle and seat post are OEM, or at least they are what came from the LBS when she purchased it new. The seat has the Electra logo on it, the post is unbranded. She said the nose was uncomfortable. She's comfortable with it now, I'm just not liking the shim.

If you have a recommendation for a post with wider range I'm all ears!

 

[Base]

The saddle and seat post are OEM, or at least they are what came from the LBS when she purchased it new. The seat has the Electra logo on it, the post is unbranded. She said the nose was uncomfortable. She's comfortable with it now, I'm just not liking the shim.

If you have a recommendation for a post with wider range I'm all ears!

Like I wrote, a traditional version as shown above, they should also sell those in the us. Candle seatpost with a separate saddle bridge clip

 

[stompandgo]

This is the clamp section of the Cane Creek Thudbuster suspension seatpost. It's probably more than you want to spend on this. Look at the clamp system. It uses horizontal bolts in the center of a circular clamp system. Look for a similar seatpost in your price range.

This is the clamp system for a Thompson Elite seatpost. It uses a two bolt system and also a two piece clamp with a semicircular bottom clamp. It even has the angle graduations. Not cheap. Again, look for something in your price range.

 

[jabberwocky]

The two bolt designs are much more robust. Single bolt designs are easier to adjust but rely on friction or serrations to keep the saddle at the angle you set, and IME are prone to moving over time. Two bolt clamps don't do that. Whether thats important at all really depends on the rider and the use to which they are putting the bike.

Posts are generally designed to have the saddle level (or very close to level) Normal seat tube angles are 70-80 degrees, so normal adjustability is probably 20-25 degrees or so.

Honestly I think the issue may be the saddle and not necessarily the post. The bike does look like it has a pretty extreme seat tube angle, but I'm guessing most posts would get the saddle level without issue. She may just not be comfortable on the stock saddle and is trying to get it pitched forward to flatten that raised nose and it isn't working. Saddles are super personal and its pretty normal to have to try a few to find one that works for you.

 

[efair]

Thank you everyone for all your comments, this has all been very helpful. I'll post a wrap-up when I get there.