New frame. Steep seat angle. Unrideable.

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PH
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Re: New frame. Steep seat angle. Unrideable.

Postby PH » 11 May 2019, 11:57am

Jamesh wrote:I know that for cars where there is a dispute then an agrieved owner would employ a expert motor engineer to produce a report on the particular issue.
I don't know whether such a thing exists. I doubt it with such a small pool of bike designers and more so steel ones.
Cheers James

That sounds ideal, maybe something Cycling UK could consider, some form of independent technical expert who could be called upon to to advise and report. Such an officer would be of great benefit to cycling in general as well as the membership :twisted:

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531colin
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Re: New frame. Steep seat angle. Unrideable.

Postby 531colin » 11 May 2019, 12:30pm

If you want to reduce toe overlap, and you don't want to think about it, you can simply move the front wheel forward, leaving the fork offset and head angle unaltered; essentially, just moving the whole of the front of the bike forward.
This will of course give greater reach, but you can reduce the top tube length by simply steepening the seat tube angle, and ignoring the inconvenient fact that moving the saddle forward relative to the bottom bracket throws the rider's weight onto his hands. I think that's a rather cynical thing to do.
There are better ways to reduce overlap that don't involve increasing the reach.
If you are making a steel fork, you can have whatever offset you want, and there is a lot to be said for using a longer fork offset on smaller bikes. Here https://spacycles.co.uk/m1b0s21p3867/SPA-CYCLES-Aubisque-105-Triple you can see 54mm offset on the smaller bikes and the more usual 45mm on the bigger bikes. Just that alone gives 9mm to play with, but this is an occasion where the laws of physics work in our favour, because a longer offset requires a slacker head angle to give acceptable trail and steering feel; just one degree slacker moves the handlebars back something like 10mm (depending on handlebar height).
However, unless you have the big budget of a major international bike company, carbon forks are generally available commercially in only 45mm offset, so if you must have carbon then there are choices to be made. Here https://spacycles.co.uk/m1b0s21p3553/SPA-CYCLES-Elan-%28105-11-Speed-Hydraulic%29 we have the ubiquitous 45mm offset, but with one degree range of head angles. I feel this is not as good an option as different fork offset, but in the real world we are limited by what is available commercially.

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 12:42pm

531colin wrote:If you want to reduce toe overlap, and you don't want to think about it, you can simply move the front wheel forward, leaving the fork offset and head angle unaltered; essentially, just moving the whole of the front of the bike forward.
This will of course give greater reach, but you can reduce the top tube length by simply steepening the seat tube angle, and ignoring the inconvenient fact that moving the saddle forward relative to the bottom bracket throws the rider's weight onto his hands. I think that's a rather cynical thing to do.
There are better ways to reduce overlap that don't involve increasing the reach.
If you are making a steel fork, you can have whatever offset you want, and there is a lot to be said for using a longer fork offset on smaller bikes. Here https://spacycles.co.uk/m1b0s21p3867/SPA-CYCLES-Aubisque-105-Triple you can see 54mm offset on the smaller bikes and the more usual 45mm on the bigger bikes. Just that alone gives 9mm to play with, but this is an occasion where the laws of physics work in our favour, because a longer offset requires a slacker head angle to give acceptable trail and steering feel; just one degree slacker moves the handlebars back something like 10mm (depending on handlebar height).
However, unless you have the big budget of a major international bike company, carbon forks are generally available commercially in only 45mm offset, so if you must have carbon then there are choices to be made. Here https://spacycles.co.uk/m1b0s21p3553/SPA-CYCLES-Elan-%28105-11-Speed-Hydraulic%29 we have the ubiquitous 45mm offset, but with one degree range of head angles. I feel this is not as good an option as different fork offset, but in the real world we are limited by what is available commercially.


The solutions you've come up with seem good ideas. I think one problem with some of the few remaining framebuilders in the UK is that they tend to have a more traditional idea of what a bike should look like. My guess is they have in their mind a certain length stem and a certain amount of visible seat post for a certain size frame with a horizontal top tube. A very short stem and one that has a big stack of spacers underneath goes against this traditional view of what a bike should look like. I don't think it's a purely cynical business calculation as you imply. It's partly about aesthetics. Their off-the-peg frames are also lugged, which introduces some restrictions depending on the lugsets that are available.

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531colin
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Re: New frame. Steep seat angle. Unrideable.

Postby 531colin » 11 May 2019, 2:04pm

Jezrant wrote:……..The solutions you've come up with seem good ideas. I think one problem with some of the few remaining framebuilders in the UK is that they tend to have a more traditional idea of what a bike should look like. My guess is they have in their mind a certain length stem and a certain amount of visible seat post for a certain size frame with a horizontal top tube. A very short stem and one that has a big stack of spacers underneath goes against this traditional view of what a bike should look like. I don't think it's a purely cynical business calculation as you imply. It's partly about aesthetics. Their off-the-peg frames are also lugged, which introduces some restrictions depending on the lugsets that are available.

Sorry, I wasn't inferring that I'd done anything unique or particularly clever. Its very common to use a range of head angles with a carbon fork of 45mm offset, and "big budget" internationals use different offsets even with carbon forks. Thorn don't like to share too much information, but you can piece together that they use different offsets and head angles on their all steel Audax bikes, or you could the last time I looked.
I don't know that the frame in question is lugged/horizontal top tube, but I don't think you will find many lugsets which will give 76 deg seat tube without modification.
The design of the frame in question is actually pushing the rider towards a short stem. If he makes the effort to get the bike to fit, he will need a big layback on the seatpost, and then a short stem to normalise the reach.

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 2:21pm

We'd have to see the frame to know for sure, but I agree that if it really is a 76 deg seat tube for a 21" audax frame, that's OTT. That's even more than my 54cm Colnago (75 deg seat tube).

srb88
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Re: New frame. Steep seat angle. Unrideable.

Postby srb88 » 11 May 2019, 9:35pm

Jezrant wrote:We'd have to see the frame to know for sure, but I agree that if it really is a 76 deg seat tube for a 21" audax frame, that's OTT. That's even more than my 54cm Colnago (75 deg seat tube).


It is, as I've measured it with 2 methods and the company confirmed it.

I would post a pic, but that would be naming them - although they back the design, so ought to be prepared for it to be scrutinised.

It's actually a damn-good looking bike - they could add it to their website gallery as much of the stuff on their is a bit traditional looking. This one combines traditional lugs with more modern tubing dimensions and kit and the straight fork looks mean!

I suspect their online pics are part there to show off the various panel work and lug lining etc they offer, which are all a bit OTT for me.

Alas, it'll be going back.

srb88
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Re: New frame. Steep seat angle. Unrideable.

Postby srb88 » 11 May 2019, 9:46pm

531colin wrote:The design of the frame in question is actually pushing the rider towards a short stem. If he makes the effort to get the bike to fit, he will need a big layback on the seatpost, and then a short stem to normalise the reach.


This formed part of my objection. The only time you would add a longer stem when you use a steeper seat angle is if you genuinely wanted a more forward seat position than you normally used and were shifting your whole position forward by X amount, so you would maintain your normal reach to the bars. A pro cyclist might do this for a very particular purpose, e.g. a short, flat stage with good roads, where the riding style was approaching TT type riding.
Conversely, and this is getting tangential, some pros move their whole position back by X amount, for cobbled stages or stages with bad roads, to relieve weight on hands on bumpy surfaces.

Having the saddle further forward seems to mean shorter cranks are needed for some riders too - rather than bringing your knees up a bit more in front of you have to bring them up into you, which means at the limits of knee and hip bending, it can be harder to get over the top of the cranks, particularly if you don't have excellent ankle dorsiflexion. Now there's nothing wrong with shorter cranks for other reasons, but having them forced on you by extreme positioning seems wrong.

Basically - you can change materials, add thru-axles, tubeless tyres and so on but I'd say there's a reason that most common aspects of design are common.

srb88
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Re: New frame. Steep seat angle. Unrideable.

Postby srb88 » 11 May 2019, 10:06pm

PH wrote:
Jamesh wrote:I know that for cars where there is a dispute then an agrieved owner would employ a expert motor engineer to produce a report on the particular issue.
I don't know whether such a thing exists. I doubt it with such a small pool of bike designers and more so steel ones.
Cheers James

That sounds ideal, maybe something Cycling UK could consider, some form of independent technical expert who could be called upon to to advise and report. Such an officer would be of great benefit to cycling in general as well as the membership :twisted:


That isn't a bad idea at all. It would be a way of formalising the expertise on forums such as this one to encourage companies to take it seriously.

I say expertise sincerely as the company was not very charitable about forum users when I mentioned that I'd consulted them - but I recognise and appreciate the wealth of knowledge and experience on forums such as this. Lurking in this space is hundreds of years of experience in the industry, countless miles ridden and a great deal of critical, logical thought and discussion about cycle product use and design.

To dismiss this is to assume the users of forums like this consume bikes like I consume laptops or phones - without knowing or caring about the detail - which couldn't be further from the truth. For better or worse, enthusiast forums are full of intelligent people who go to bed thinking about their chosen interest.

It's obviously a delicate area, as by nature the companies hand-making frames or at least designing them in the UK are small companies which we generally want to support in the face of multinationals. The situation in which such a body would be most useful (e.g. a case such as mine) would mean engaging in a dispute with a small, potentially fragile company or even one-man-band. I know one such one-man-band who would tell such a body where to go. You're less likely to need them when dealing with the large shops or manufacturers as they're generally more willing and able financially due to scales of production to sort you out to keep you happy.

But yes, generally an appointed individual with technical expertise that could represent the consumer would be a great addition to the CTC offer. In my case, I think I argued the case pretty well, but because of the stress/time it would cause to pursue the issue for longer, I'm likely to lose a chunk of cash just to get it sorted. An appointed technical expert could perhaps take my technical arguments and act as a more neutral arbiter while I got on with my life, and get back to me with the outcome or offer. Or at the very least, be CCd into the emails to add some weight to the matter.

srb88
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Re: New frame. Steep seat angle. Unrideable.

Postby srb88 » 11 May 2019, 10:13pm

Re the above suggestion for an appointed technical advisor - doesn't Richard Hallet build frames and write for Cycling UK?

Ooh his frames are nice. I could kick myself for not getting one of his but they're a bit more than this one was. Not a lot though...

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 10:42pm

Don't see any geometry charts on Hallett's website either. :roll:
Last edited by Jezrant on 11 May 2019, 11:08pm, edited 1 time in total.

srb88
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Re: New frame. Steep seat angle. Unrideable.

Postby srb88 » 11 May 2019, 11:05pm

Jezrant wrote:Custom frames? :lol: Now there's a real can of worms. Don't see any geometry tables or specs on his website either. :roll:


Course, but you'd hope that as it's custom, they would have deeper discussion with you on enquiry and before order. At least what you currently ride, etc.

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 11:10pm

Ah, you're caught me there. There's something still a bit of mystery. You clearly know an awful lot about how to get a proper fit on a bike. Why didn't you ask for detailed information about the frame's geometry before handing over your hard-earned cash?

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 11:12pm

srb88 wrote:
Jezrant wrote:Custom frames? :lol: Now there's a real can of worms. Don't see any geometry tables or specs on his website either. :roll:


Course, but you'd hope that as it's custom, they would have deeper discussion with you on enquiry and before order. At least what you currently ride, etc.


Unless you do a CAD and get them to agree on it, it's all on trust. Just as it was with the people you bought your OTP frame from.

Samuel D
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Re: New frame. Steep seat angle. Unrideable.

Postby Samuel D » 11 May 2019, 11:39pm

srb88 wrote:I say expertise sincerely as the company was not very charitable about forum users when I mentioned that I'd consulted them - but I recognise and appreciate the wealth of knowledge and experience on forums such as this. Lurking in this space is hundreds of years of experience in the industry, countless miles ridden and a great deal of critical, logical thought and discussion about cycle product use and design.

To dismiss this is to assume the users of forums like this consume bikes like I consume laptops or phones - without knowing or caring about the detail - which couldn't be further from the truth. For better or worse, enthusiast forums are full of intelligent people who go to bed thinking about their chosen interest.

Well said. This forum is a treasure. I think the knowledge, experience, and understanding is plain to see for anyone who reads it for a while. That includes Jezrant of this thread who, while not showing much sympathy, taught the both of us and probably other readers that traditional British builders used very steep seat tubes on small frames. I would never have guessed that, not being old enough to have seen it for myself. I enjoy having access to that experience through this forum.

Jezrant
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Re: New frame. Steep seat angle. Unrideable.

Postby Jezrant » 11 May 2019, 11:47pm

Careful now, I said 'some' not all old school British framebuilders still use steep seat tube angles on small frames. I know at least two who have evolved with the times. And even Colnago has learned to relax their racing frames, slightly. :lol: