Cycling UK Forum

I am having difficulty getting my Brooks Team Pro far enough back on a Chorus carbon seatpost. Can anyone suggest a post with more set back. Brooks seem to have very short rails compaired to some saddles. I am a vertically challenged person so my frame has a steep seat angle and this results in my saddle being too far forward. I don't have this problem on my other bike as I have an Arione with geet long rails on it.

Thanks for the link Colin. I suppose I should have done a search first.

I have a Brooks Team Pro on a Campag Victory circa 1986 seatpost. It goes far enough back for me and I never thought it was an issue.

My Campag seatpost has a clamp thing on the top with a big Allen bolt to tighten it.

The nose of the saddle is 2 and a half inches behind the BB.
Perhaps I can move it 1" back or forward from that position.

How far back do you want yours?
Is your frame too small? You may need a longer stem.

The Mechanic wrote:Thanks for the link Colin. I suppose I should have done a search first.

Dont beat yourself up about it!
Interesting that (our) requirement for lots of layback doesnt seem to be tied in to any physical characteristic that I have found.
I wish I had bought one or two EA 70 posts while they were available in long layback, but I was too mean and thats the end of it.
Now my choices are down to the adaptor thingie, making my own, or making do with a standard hockey stick post.

Please don't think I'm criticising or making poor observations, but the saddle should be under your bum, and your bum is a particular distance from your feet and it is also a particular distance from your 'bars. For efficiency, the front of your saddle should be above, or slightly behind, your bottom bracket and your frame should be the right length so you can reach the 'bars comfortably.

Taking all that into account, why should you have to play around with seatposts?

Why are not frames and components the right dimensions?

Mick, I think the answer lies within the OP's 1st post.

Yes Jerry, I read that, but I still don't understand.

If the saddle won't go back far enough, surely the frame is too short?

Therefore it's not a seatpost problem, rather it's a geometry problem.

Mick F wrote:Yes Jerry, I read that, but I still don't understand.

If the saddle won't go back far enough, surely the frame is too short?

Therefore it's not a seatpost problem, rather it's a geometry problem.

The way I see it, but it would be helpful if Mechanic could confirm it, his frame is made with a steep seat tube angle, probably to create space for toe/front wheel clearance (because it's a small frame). This results in a relatively short top tube angle. To negate this, unless it is a time trial frame, the long lay back is necessary to compensate for the steep seat tube angle.

I have often suspected I may be a funny shape, and I think I have just proved it.
At 5 feet ten inches, I struggle to get my Brooks saddles far enough back for comfort, on frames with fairly conservative seat tube angles (71, 72)
For the first time ever, I have just tried the KOPS business on my "most used" bike (although seat setback from BB is much the same on them all). BINGO - my knee is as exactly as I can tell with a plumbline over the pedal spindle. Am I doing it right? Im holding the string on the little bump on the top of the shinbone, crank horizontal, pedal at front.
Im not exactly tall, do I have a long thigh bone for my height?

Crepello is correct in most respects. Firstly, the frame is a stock taiwanese frame, not made to measure. Being a small frame means that the seat tube angle is steeper than would normally be desirable on a touring frame. If you look at the dimensions of stock frames from all the major manufacturers you will see that the seat tube angle gets steeper the smaller the frame gets.

This all means that the top of the seat tube is closer to the BB in the vertical palne. Therefore the saddle, given a "normal" seatpost will be further forward than on a larger frame. Thus, in order to get the saddle a given distance behind the BB, you need a the saddle to be further back in the seatpost clamp. If you run out of rails then you need either a saddle with longer rails or more setback on the seatpost. I know in an ideal world I would get a made to measure frame and all will be well. But not everyone has the resources to get made to measure frames so I am stuck with the one I have got.

The length of the frame (i.e. the top tube length)is not relevant to the postition of the saddle in relation to the BB.

Mick F wrote:Yes Jerry, I read that, but I still don't understand.

If the saddle won't go back far enough, surely the frame is too short?

Therefore it's not a seatpost problem, rather it's a geometry problem.

Mick, I had the same issue in reverse with a Brooks and had to get an inline seatpost, you may vary from bike to bike but I try to keep my saddle to BB relationship the same. In trying to get this right across my bikes I wasted money and time before fully understanding:-

think of the BB as a pivot point around which the triangle of seatube, downtube and toptube can rotate. If you had two bikes with the same length TT but different seat tube angles then the steeper the angle the more top tube is forward of the BB. Some manufacturers give the BB to HT measurement as a virtual 'reach' in the same way they give effective top tube. They are assuming you will position the saddle at the same distance behind the BB. Therefore to select the correct frame you need to know this reach figure, Cervello do this.

so you've selected a frame that gives you the correct BB to HT reach coupled with your preferred stem length. Now you come to position the saddle and saddle rail length and saddle height will dictate what seatpost can be used. The higher the saddle is the further back from the BB it's moved, and vice versa. For a short railed Brooks this can mean that a low position saddle needs a lot of seatpost setback to get the saddle to BB correct. Whereas a high saddle may mean that an inline, zero setback, seatpost is needed.

Since my early errors I always fine tune my bike fit beginning with saddle and working forward. If you end up with an extreme of stem length then maybe the frame isn't right for you.

I have recently bought a Van Nicholas Yukon and have been looking for the elusive large layback seatpost for my Brooks. I need 8.5cm BB to front of saddle. I have tried the Nitto posts but they haven't quite got enough.

The Velo Orange Gran Cru mentioned above fits the bill perfectly for me and still has some spare:
http://www.freshtripe.co.uk/Freshtripe/ ... posts.html

My only issue now is the post keeps slipping. They are both supposed to be 27.2mm. The post is fine in my Bob Jackson but slips in the Yukon. I have tried carbon paste and now wait for a beefier seat collar to arrive.
Cycling shouldn't be this frustrating!

Thanks guys!
I understand.

I didn't realise that the smaller frames made that much difference to saddle position, but it's obvious now it's been pointed out. I was right about it being a "geometry problem" but not one that can be solved easily.

The REALLY stupid thing is, they make the seat tube angle steep on small frames in order to shorten the top tube.
However, this short top tube is entirely spurious, because, as we have seen, all that happens is the rider goes looking for a long layback seat post. They call themselves designers, they make me want to spit.
The correct way to shorten a frame is to use a shallow head angle, with a long fork offset to bring the trail back to something sensible. both shallow head angles and long fork offset move the front wheel away from the riders toes, one occasion when the laws of physics conspire to help us! If that is not enough, there is nothing else for it except to use a smaller wheel.
Spa are prototyping touring frames I have designed. Just 3 sizes, so nothing really tiny, 51, 54 and 57 cm with 6 or 7 cm top tube slope. All sizes use 71deg head and 54mm fork offset. Its not hard.