Top Tube clearance on a road-bike

[SteveT]

It seems that 2009 is the year of new road frame-set for more than a few people here, and I am now perilously close to buying a new one myself. While the Yen is so strong - and before the revolution comes - I'm thinking to order online from the UK.

I've found a lovely looking thing, which demands immediate and excessive visa card payment before I have time to see the sense of it all, but I'm a bit worried about getting the sizing right. Thing is, it's a "classic" frame geometry, and all I've ridden up to now is the compact / sloping top-tube type. Sending a mixture of body and bike measurements, the maker got back to me with a recommended frame-size: the key geometry basically seems to look pretty spot-on: top-tube length, head-tube, etc. The only thing that I found rather shocking was the seat-tube length... what is a 53cm on my current compact-frame has now grown into a whopping 59cm ! Depending on the accuracy of my inseam measurements, worst case this might work out to a stand-over clearance (without shoes) of as little as 1.5cm ... !

The maker says "don't worry, this is a perfect fit", and apart from this clearance worry, the CAD diagram he sent certainly seems to measure up that way. Furthermore, from a google search on the internet it seems that only one to two inches is recommended for road bikes anyway, and a lot of people seems to be riding with even less ...

But I can't help playing unusual dismount & crash scenarios in my head, almost all of which bring real tears to my eyesuch:. So my question to the forum: am I worrying about this issue unnecessarily ? Has anyone gone through a similar dilema ? Are the family jewels really safe ?

I would want to keep this (and them) for a long long time so any advice appreciated...

Cheers
Steve

PS. And this is what I'm looking at:
http://www.enigmabikes.com/index.php?_a=viewProd&productId=26

 

[trad]

wonder how they measure....

steve - looked at the geometry charts... Either Enigma measures seat tube in non traditional ways or the geometry is quite unique....

According to the Enigma geometry, your size 59cm has a 56cm top tube. For me, this is odd unless they measure bottom to top on seat tube.

Litespeed and Merlins measure center to top of top tube. I had an 59cm Litespeed (classic geometry) that had top top tube of 57.5cm. My current slopng tube Ti is 58cm vitual (center to center) and has a 53cm actual seat tube. The top tube on this guy again is 57.5cm.

Assuming Enigma measures bottom to top, I'd think your size 59 cm (w/56cm top tube) is the equivalent of M or M/L sized sloping frame. Recommend asking how they measure and what their stand over height is at midpoint of top tube.

 

[AlanW]

Drawing?

Can you post up the CAD drawing?

Looks like the Enigma has a slightly extended seat tube, to give clearance for the seat collar. If they are measuring centre-to-top instead of centre-to-centre, and the top tube is horizontal, that could easily account for the long-looking figure. I would expect the centre-to-centre dimension to be roughly equal to the top tube length.

 

[SteveT]

Hi Trad, Alan,

Thanks for the feedback. This is the CAD drawing that they sent ... it also has standover height drawn in (817mm) which seems to confirm the rather high seat tube:

What do you reckon ?!

Cheers -
Steve

 

[kiwisimon]

AlanW called it, they are measuring to the top of the seat tube so there is your extra inch. It all looks right, fairly square geometry relaxed angles. re the stand over height its fine, think about a road crash, you are always gonna go over the bars not some slow speed dab like on a mama chari. Your jewels will be fine unless you keep them behind your ears

 

[AlanW]

SteveT,
I had a play with http://www.bikeforest.com/CAD/bikeCAD.php

Looks like a 590mm centre-to-top measurement on the seat tube is bang on for this bike, giving a centre-to-centre dimension of around 560mm which is right for the top tube length.

Buy the frame and enjoy it!
AW.

 

[SteveT]

AlanW called it, they are measuring to the top of the seat tube so there is your extra inch. It all looks right, fairly square geometry relaxed angles. re the stand over height its fine, think about a road crash, you are always gonna go over the bars not some slow speed dab like on a mama chari.

Thanks kiwisimon - with shoes then, the clearance will work out worst case about an inch or so. Maybe I'll try to learn that old sumo trick ...

Your jewels will be fine unless you keep them behind your ears

Yeeess, well, if I was in a position to choose to heave my bits over my shoulder I'd be a happy man indeed. Thanks !

 

[kiwisimon]

Thanks kiwisimon - with shoes then, the clearance will work out worst case about an inch or so. Maybe I'll try to learn that old sumo trick ...
!

easier to lean the bike a little to the side. have fun on what will be a sweet ride. are you getting the polished frame?

 

[TODO R CASPELL]

Codger Fit

I think you will be FINE with that. Conventional classic old school bike fit is an inch or two clearance between your boys and the top tube for road bikes and six or so for mountain bikes. Just stand over it and raise the front wheel untill the top tube makes contact and measure the air below your tire.
Road bike should have about a fistfull of seat pin showing. I think the whole micro drive sloping frame is BS foisted upon an unsuspecting bike market in order to save a few inches of frame materiel. Or maybe just to look like a Mt bike ? I dono WHAT the justification is. But you should not need to run a MTB seat post on a road bike.

From here on out I will take my top tubes FLAT thank you.

PS Sorry to rant .
PPS. I looked it is BEAUTIFUL bike.

 

[SteveT]

AlanW - wow, thanks for putting this through what looks a complicated tool... I had a quick go myself and ended up with the handlebars somewhere around the crank... will try again.

kiwisimon - not too sure what kind of finish I'll go for. Frames are mirror polished as standard and then there are a few options with the logo (mirror polished, "bead blasted", etc). A bit pricy for these extra touches but I probably should do - in for a penny, in for a pound ...

TODO - thanks, having just turned forty a few weeks ago, the "codger fit" applies nicely... and before you ask, yes, this is indeed all tied up with a mid-life crisis !


Anyway, thanks very much guys. I'm still going through the process to justify the purchase to myself and have started the strategy of doing LSD to help: "Long, Slow, Distance" as the bloke in the LBS calls it. A few rough mountain roads and a century+ of distance per ride on my aluminum frame has started to knock my internal organs around enough that before long I'll break, get my visa card out, and put in that order ....

Cheers
Steve

 

[kiwisimon]

kiwisimon - not too sure what kind of finish I'll go for. Frames are mirror polished as standard and then there are a few options with the logo (mirror polished, "bead blasted", etc). A bit pricy for these extra touches but I probably should do - in for a penny, in for a pound ...

Anyway, thanks very much guys. I'm still going through the process to justify the purchase to myself and have started the strategy of doing LSD to help: "Long, Slow, Distance" as the bloke in the LBS calls it. A few rough mountain roads and a century+ of distance per ride on my aluminum frame has started to knock my internal organs around enough that before long I'll break, get my visa card out, and put in that order ....

Cheers
Steve

Steve
for what its worth I got blasted mainly so snot, sweat and other icky crud like sun screen etc. could be banished with a simple wipe of a sleeve. LSD is a good style of riding but yeah Aluminium can be rough.

 

[SteveT]

Steve
for what its worth I got blasted mainly so snot, sweat and other icky crud like sun screen etc. could be banished with a simple wipe of a sleeve.

Never really considered that actually - so I checked again and realised I was wrong... the Enigma finishing is brushed, not polished. Which should make cleaning and removing scratches much easier.

Took me a moment to figure out in your pics that you had the same bike with a different wheelset.... unless you really have treated yourself to two identical Strong custom titanium frames ?! ...

Cheers
Steve

 

[kiwisimon]

... unless you really have treated yourself to two identical Strong custom titanium frames ?! ...

Cheers
Steve

really don't need more than one. My racing days are over and I can keep up with most club riders on the slicks so two? No.