Mercian bike fit experience

[Oxford_Guy]

You could compare the geometries using a visual tool? This one was mentioned in a thread the other day: http://gearinches.com/blog/misc/bike-geometry-comparator

I'll take a look, though I don't think I have all the necessary measurements for both bikes

[Cudzoziemiec]

BTW one other thing that has been abit on my mind, when I was measured for the Mercian, Grant asked me to put my hands where I would normally ride (when cruising), so I put them not on the hoods themselves, but set back from them, where the bars start to curve forward, with my thumbs hooked under the top bar - as this is how I generally ride (except in busy traffic/in town/going down hill) on my touring bike (and how I was measured up by Paul Hewitt for my Cheviot, as that's what he suggested). So I think Grant my have measured my "optimal" riding position to their rather than on the hoods, but on a road bike, are you generally meant to be on the hoods pretty much 90% of the time? In which case, am I likely to be a bit stretched on the hoods? I've also only tended to use the drops for downhill or headwinds or if just really going for it on a long straight. Having said that, I don't think I felt too stretched-out on the hoods (or drops) on the jig.

My Veloce Ergos are comfortable to ride on the hoods (I used to have them on my Cheviot before I switched to bar end shifters on that, before I sent them off for a complete overhaul) it's just not how I've been riding on my Cheviot most of the time.

"Are you generally meant to be on the hoods 90% of the time?" A lot of people do ride like that but there's no "should" about it. If you prefer to ride with your hands a bit further back most of the time, I can't see why that shouldn't be right for you. After all, you were asked to put your hands where you normally have them, not on the hoods. On the hoods (or the drops for that matter) obviously saves a split second in braking or shifting, but apart from that, does it matter?

[DuncanM]

If you are intending to ride this bike in a bunch, I would expect you to want to be able to brake without having to move your hands?

[Oxford_Guy]

If you are intending to ride this bike in a bunch, I would expect you to want to be able to brake without having to move your hands?

Well I was thinking of using it for club rides, though not racing

[Oxford_Guy]

I think I may have quite a list of questions for Grant, though I understand that email communication is not (or at least wasn't) Mercian's forte...

[Brucey]

re frame size; I think (purely on aesthetic grounds) that many people are riding frames with horizontal top tubes that are too small, and that anytime you are planning to have as much or more exposed seat pin vs the length of the head tube, the frame starts to look a bit small.

Practically speaking you need to be able to straddle the frame without being castrated (and you may only need about 2" of exposed seat pin for this) and you need to be able to put the handlebars at the right height.  If you are racing and need the bars very low then this might be a good reason for having a smaller frame size but you might as easily need to go the other way. My guess is that with a 52cm frame you might struggle to get the handlebars level with the saddle unless you use a stem that is longer than normal, and that the lowest adjustment is a lot lower than you might ever use. If that is right then a frame that is 1-2cm longer in the seat tube might be a good idea; it would arguably fit better with the retro aesthetic too.

Again on a practical note, the shorter the head tube is, the greater the load is in the headset bearings; small frames tend to have more headset troubles than medium sized ones for this reason. For similar reasons the ride of a small sized frame is always less comfortable than a slightly larger one if the fork flex is the greater part of the total flex in the front end of the frame (and it usually is). It may not look like it but the flex at the fork tips arises from the deflection in the fork blades, bending in the main frame (i.e. top tube and down tube) and cantilever bending in the steerer tube. In some cases each of the three things can make a similar contribution to the total movement.  The cantilever bending angle (i.e. the angle through which the headset races are required to articulate) is extremely sensitive to steerer length and in very large racing frames built with 1" steerers it can easily become excessive (witness Jobst Brant's many diatribes on the inadequacies of/wear within headsets; had he not had a frame with a ~10" head tube and a light-built steerer he'd have had no worries; as it was two or three balls at the front of the lower race took a massive load because the steerer flexed so much...).  Anyway increasing the cantilever length (i.e. separation of the headset races) by 20% increases the cantilever deflection by over 70% so just changing the frame size by 2cm can completely transform the way the bike rides the bumps.

 Note that because the steerer is butted internally, it isn't unusual for the downwards adjustment of a quill stem on a small frame to be limited by the bottom of the stem clashing with the top of the butt; you may not have as much downwards adjustment (or total range) as it appears and again a slightly larger frame would perhaps have been better idea. The framebuilder ought to ask about the required handlebar adjustment range if there is a danger of a clash like this, since the fork can be built with a slightly different trim on the steerer tube if necessary, i.e. it may be trimmed more than normal at the base of the steerer.   [Small OTP frames are often very compromised in this regard, e.g. because they have the same trim as normal on the steerer; I have several times seen bikes with only ~1cm of legitimate height adjustment; any lower and there is a clash with the butt; any higher and the limit mark appears....]

cheers

[rogerzilla]

Threadless stems are cheap if you need to muck about with the reach.  It's rare to get it right first time.  On various frames, I've had stems from 30mm to 135mm. 

As a rule of thumb for a road racing frame, the frame size is wrong if you don't have a 10-12cm stem in a medium 21-23" frame, an 8-10 on a small frame (say 20" or smaller) and a 12-14 on a large frame (say 23.5" plus).  However, that was based on 1970s Italian geometry and times have changed.  Plus, 70s Italian racers fitted a 14cm stem regardless of ergonomics,  because it looks cool to have a long quill stem.

[Oxford_Guy]

Threadless stems are cheap if you need to muck about with the reach.  It's rare to get it right first time.  On various frames, I've had stems from 30mm to 135mm. 

Yes, but I want a threaded stem...

As a rule of thumb for a road racing frame, the frame size is wrong if you don't have a 10-12cm stem in a medium 21-23" frame, an 8-10 on a small frame (say 20" or smaller) and a 12-14 on a large frame (say 23.5" plus).  However, that was based on 1970s Italian geometry and times have changed.  Plus, 70s Italian racers fitted a 14cm stem regardless of ergonomics,  because it looks cool to have a long quill stem.

I think I remember Grant at Mercian saying (not his exact words) about not liking to spec a bike frame so that it would require a very long stem. He seemed to think 9cm would work with the frame specification produced.

[Oxford_Guy]

re frame size; I think (purely on aesthetic grounds) that many people are riding frames with horizontal top tubes that are too small, and that anytime you are planning to have as much or more exposed seat pin vs the length of the head tube, the frame starts to look a bit small.

I'm inclined to agree and confused by the drawing Mercian gave me, which seems to suggest 17,3cm from the top of the seat tube to the top of the saddle, which I think is way more exposed seatpost than it looked on the jig in the shop (that was more like a large hands-width - and even at the time I thought that was perhaps a little much seatpost showing) - in fact on my sloping compact frame Hewitt it's only 0.6cm more, and that has loads of seatpost showing!

Practically speaking you need to be able to straddle the frame without being castrated (and you may only need about 2" of exposed seat pin for this) and you need to be able to put the handlebars at the right height.  If you are racing and need the bars very low then this might be a good reason for having a smaller frame size but you might as easily need to go the other way.

You can also get quill stems that point downwards at a steeper angle, which would be another way to lower the bars

I think one of the reasons for having a bit of exposed seatpost was to allow space above the wheel/stays for a saddle bag, but wouldn't increasing the seat tube have a similar effect?

My guess is that with a 52cm frame you might struggle to get the handlebars level with the saddle unless you use a stem that is longer than normal, and that the lowest adjustment is a lot lower than you might ever use. If that is right then a frame that is 1-2cm longer in the seat tube might be a good idea; it would arguably fit better with the retro aesthetic too.

I think he was suggesting adding some tube height to the headtube *above* the level of the top tube, but I'm not exactly sure what he meant or how this would look

I really don't understand how a non-compact frame can be smaller than the compact one on my Hewitt and still fit me, though. Seems odd!

[Paul H]

I think he was suggesting adding some tube height to the headtube *above* the level of the top tube, but I'm not exactly sure what he meant or how this would look

It's not that unusual, if you put "Mercian extended head tube frame" into Google images you'll see some examples.

[Brucey]

I think he was suggesting adding some tube height to the headtube *above* the level of the top tube, but I'm not exactly sure what he meant or how this would look

It's not that unusual, if you put "Mercian extended head tube frame" into Google images you'll see some examples.

I'd sooner have a slightly larger frame than that TBH, but it is all in the eye of the beholder...

cheers

[Oxford_Guy]

I think he was suggesting adding some tube height to the headtube *above* the level of the top tube, but I'm not exactly sure what he meant or how this would look

It's not that unusual, if you put "Mercian extended head tube frame" into Google images you'll see some examples.

I'd sooner have a slightly larger frame than that TBH, but it is all in the eye of the beholder...

I think I would to e.g. I think this frame has an extended headtube, but looks like the top bar could just be a bit higher? Although I guess that would change the position of the seat stays?:

(click to expand image)



Also in that picture note non-use of secu-clips, short drop brakes and close-fitting mudguards! \o/

BTW If I'm reading the geometry diagram from Mercian correctly, it seems to be suggesting a height of 17.3cm (6.8") from the top of the seat tube to the top of the saddle, which sounds an awful lot of exposed seatpost for a bike with non-compact geometry, even taking into account the increased height above the saddle rails a leather saddle top like the Gilles Berthoud I'm thinking of using would have compared to a modern road bike saddle. If the seat tube was 54cm instead of 52cm this would still be 15.3mm (6"), which sounds like more than enough, no?

[rogerzilla]

That Ron Cooper definitely has an extended head tube - look at the top lug.

A Nitto Technomic is another solution.

[Oxford_Guy]

That Ron Cooper definitely has an extended head tube - look at the top lug.

A Nitto Technomic is another solution.

The Nitto Technomic does indeed look very tall, but not sure that would be a good look either: https://www.hubjub.co.uk/nitto-stem-technomic-deluxe-153-p.asp

I suspect I may have to pay another visit to Mercian to discuss, I'm also not 100% sure whether how the reach is configured going to be right for me and still haven't made my mind up yet about the whole mudguards/long-drop brakes issue... argh!

It's possible I'm not making things easy for them, by choosing a "road" model, but not wanting an overly bent-over riding position (due to issues with a bad back). Perhaps the (less pretty) Audax Special would have been a more sensible choice, but I was deliberately wanting quite a different and sportier bike than my Hewitt Cheviot tourer, which as configured (with 32mm Marathon Supreme tyres and relatively high 46/34/24 and 11-32 gearing), isn't far off an Audax-style bike (well, apart from the very long chain stays, heavy stainless steel Tubus rack, full hub dynamo setup and heavy-duty DT Swiss TK540 36 spoke wheels... <ahem>)

I was originally considering a (fillet-brazed) Rourke...

[hubner]

That is the current frame sizing fashion, ie very low top tube for no real reason except for fashion. The only reason for a low top tube is if you want very low bars, the extreme version would be a lo-pro frame.

That frame with that position without the extended seat and head tubes would not be even usable using that seatpin and stem because they would be higher than the minimum insertion.

In Mercian's drawing:
top of saddle to bottom bracket - 693mm
seat tube (centre to top) - 520mm

if you use a typical quill stem, eg Cinelli 1A, even at max height, the bars will be quite low.

I'm a bit shorter than the OP, my bike is a 40 year old steel frame, 530mm seat tube c-t, top of saddle to bottom bracket is about 680mm, and I would not want the top tube any lower.

[Oxford_Guy]

That is the current frame sizing fashion, ie very low top tube for no real reason except for fashion. The only reason for a low top tube is if you want very low bars, the extreme version would be a lo-pro frame.

That frame with that position without the extended seat and head tubes would not be even usable using that seatpin and stem because they would be higher than the minimum insertion.

In Mercian's drawing:
top of saddle to bottom bracket - 693mm
seat tube (centre to top) - 520mm

if you use a typical quill stem, eg Cinelli 1A, even at max height, the bars will be quite low.

I'm a bit shorter than the OP, my bike is a 40 year old steel frame, 530mm seat tube c-t, top of saddle to bottom bracket is about 680mm, and I would not want the top tube any lower.

Interesting, and you find it okay to straddle the top tube without having to sit on it? Sounds like I could go up to at least a 530mm or even 540mm seat tube, raising the headtube below the top tube by a similar amount - there'd still be reasonable amount of seat post showing, and am pretty sure the stem would be low enough (I don't think I would want the bars as far beneath the saddle as in the photo of the Cooper), though I guess whether I'd be able to straddle the top tube comfortably would depend a little on the bottom bracket height (which I couldn't tell when in the jig, as that was high off the ground).
The seat stays wouldn't be in the same position, though, which I guess could change the feel of the bike?

[Oxford_Guy]

I'm a bit shorter than the OP, my bike is a 40 year old steel frame, 530mm seat tube c-t, top of saddle to bottom bracket is about 680mm, and I would not want the top tube any lower.

Do you have a picture of your bike?

[Brucey]

...Interesting, and you find it okay to straddle the top tube without having to sit on it? Sounds like I could go up to at least a 530mm or even 540mm seat tube, raising the headtube below the top tube by a similar amount - there'd still be reasonable amount of seat post showing, and am pretty sure the stem would be low enough (I don't think I would want the bars as far beneath the saddle as in the photo of the Cooper), though I guess whether I'd be able to straddle the top tube comfortably would depend a little on the bottom bracket height (which I couldn't tell when in the jig, as that was high off the ground).
The seat stays wouldn't be in the same position, though, which I guess could change the feel of the bike?

the blue bike in the photo above would still have a head tube longer than the exposed seat pin if it were built ~1" bigger, so would fail my (admittedly highly subjective and maybe retro)  rule of thumb. More practically speaking with frame sizing like that only a tall stem would give you a handlebar anywhere near level with the handlebars.

 Years ago (before the use of a-head on road bikes)  I realised that the exposed part of the quill stem was pretty flexy so I had a road bike built with an extended steerer and used a spacer between the threaded and adjusting races of the headset. This meant that there was less flex. [It also meant that I could have raised the stem to a level where the wedge was close to - and therefore stressing more-  the threaded part of the steerer, which would have been a bad thing; in reality I accepted a smaller range of height adjustment in return for a bit of added stiffness.] This scheme had the advantage that a few minute's work could transform the steerer to a 'standard one', whereas shortening an extended head lug is a bit more involved.

Re straddling the top tube; because of how the saddle height is usually set, on a road bike the distance from the pedals to the ground can be about the same as the distance of the saddle top to the top of the top tube,   and you can still straddle the top tube OK. This minimum is thus about 4" or so, in contrast to the ~8" or so that might be the current trend when you are fitted on a frame of about that size.

 Fashions vary; a long time ago (in the 1950s) the fashion in the UK appears to have been to use as large a frame as possible, more or less. If you had more than ~3" of seat pin showing you were in danger of running out of it (seat pins were built short back then) and might be advised to get a frame 1" bigger. Fit-wise this made little difference since frames were often built with hardly any variation in top tube length.  I also wonder if in fact this was entirely pragmatic, bearing in mind that larger frames ride so much better (more comfortably) even if they are built in fairly heavy gauge tubes.

 In the 1980s IIRC campag built their aero-styled seat pins in two different styles; one with a 'long' aero section (for racing bikes) and one with a short aero section (for touring bikes, very small frames or for those adhering to  a fit using  a larger frame size).  The long version allowed the saddle (varying with rail height etc) to be between ~6" and ~8" above the top tube and the short version was about 2" lower than that.

So (bearing in mind you don't want to use very low set handlebars) I think you might be OK with a drop from the saddle to the top tube (of a standard frameset i.e. one that does not have extended lugs) of about 6"-7" .  Very much less than this and you are going to run into straddling issues and very much more than this and you will not be able to use a standard quill stem, probably.  I  dunno how that compares with the frame design as you have it at present.

cheers

[DuncanM]

That Ron Cooper definitely has an extended head tube - look at the top lug.

A Nitto Technomic is another solution.

The Nitto Technomic does indeed look very tall, but not sure that would be a good look either: https://www.hubjub.co.uk/nitto-stem-technomic-deluxe-153-p.asp

They are (intentionally) tall, but they are shiny, so I think they look fine (please ignore the badly installed aero bars):
IMG_20171220_154515 by duncancmartin, on Flickr
IMG_20171220_154313 by duncancmartin, on Flickr

This is close to the top of the range of adjustment of the stem (but I haven't set the saddle up as high as I need it as I'm not riding it any more).

[Brucey]

this bike



IMHO fitted its rider (Tommy Simpson) very well.

IIRC Peugeots of this type used ~72 degree seat angles. With the saddle and seat pin used, I don't think the saddle could go more than ~10mm further back than it is and a 74 degree seat angle would not have been possible unless the saddle and seat pin were changed.

The bars look quite high (for racing) until you clock the depth of the bars; they are enormous drops! Also when getting down to it on the hoods/tops, it was expected that your forearms would be about horizontal; no need for the tops to be super-low if you ride like that.



a decade on and the bike setup wasn't that much different



de Vlaeminck's bike is an interesting case in point simply because he rode such great distances on it; he would often ride 100km plus to early season races, race, and then ride home, making for days that involved 350km plus in the saddle.

Only a pro rider would be able to maintain this low body position



but you can see that it is achieved without having the bars set low; he was comfortable for long periods like this  and of course very fast. Doubtless if he was set up in the modern vogue he would be riding a frame 3cm smaller with the bars set lower, but if he were I think he would be less comfortable and very probably slower, too.

cheers

[hubner]

I'm a bit shorter than the OP, my bike is a 40 year old steel frame, 530mm seat tube c-t, top of saddle to bottom bracket is about 680mm, and I would not want the top tube any lower.

Do you have a picture of your bike?

the top of the saddle to top of  seat tube is 135mm.The top tube just about touches when I straddle the bike. The cranks are 165mm.

I've measured the frame again, it's actually 53.5cm c-t and 52cm  c-c.

This blue bike is 54cm c-t or 52.5cm c-c. Standover height is 5mm higher than the first silver bike but still not a problem.

I think the exposed seatpin is a bit short relative the the head tube length purely from an aesthetic point of view (only 5mm or so), but better for higher bars though. Cranks are also 165, 170 would lower the saddle by 5mm and I think that would make the exposed seat pin appear too short.

Actually, I've also got a 51cm c-c frame and a 50cm c-c frame, I bought them new and left the steerer long and fitted headset spacers. The 50cm c-c frame definitely needs the spacer otherwise the bars would be too low even with the quill stem at the max height.

All are steel frames with horizontal top tubes with threaded headsets.

[hubner]

The changes in frame sizing and set up:

top tubes got lower
head tubes got shorter
bar tops got lower
brake levers mounted further up the bars (sometimes higher than bar tops)
drops got shallower
stems point upwards
straight arms
lots of headset spacers

[Oxford_Guy]

The changes in frame sizing and set up:

top tubes got lower
head tubes got shorter
bar tops got lower
brake levers mounted further up the bars (sometimes higher than bar tops)
drops got shallower
stems point upwards
straight arms
lots of headset spacers

For this bike I think I mostly want the opposite of all that,

[Samuel D]

head tubes got shorter

And then they recently got longer again, although this time with short seat tubes and sloping top tubes to square that circle.

bar tops got lower
[…]
drops got shallower

A combination that effectively reduces the range of positions available, but no-one cares since they have a bicycle for every occasion whether fast rides, slow, or anything between. If you have one bicycle that you use for everything, it still makes sense to have the bar tops higher and use handlebars with a good dollop of drop and reach.

Vroomen has some observations on handlebar height over the years in these short blog posts. Read them in order:

• One
• Two
• Three
• Four

Ideally you’d know the basic arrangement you want before going to a frame builder, but I suppose they’re used to customers changing their mind a few times.

If you want high handlebars, a larger frame seems a more natural starting point. I think standover height is talked about more than it deserves. Even if you can’t strictly stand over the upright bicycle with both feet on the ground, you’ll soon get used to leaning the bicycle to lower the top tube and/or standing on the toes of one foot only. Millions of ten-year-olds automatically mastered this when they learned to ride on adults’ bicycles.

[hubner]

head tubes got shorter

And then they recently got longer again, although this time with short seat tubes and sloping top tubes to square that circle.

I think short short tube came about with compact frames and threadless headsets. Hence the spacers, upward pointing stems and brake levers and rotated bars on most current bikes.

There's a natural limit on how short head tubes can be with quill stems.