Small frames: high trail or toe overlap?

[fpavao]

Hello,

just wondering what do you guys prefer when making very small road frames, for 700c tires: a slacker HT angle (affecting trail for a road fork) or just learn to live with a lot of toe overlap?

I don't mind toe overlap, as I'm short myself and my personal bikes usually have some, but for a urban fixed gear I find it very annoying, sometimes dangerous.

Regards.

(forgot to say: I've made a frame for a very short guy, about 1,60m I think, without toe overlap. The resulting trail was about 70mm or something like that. I rode the bike to test it and found it terrible, decided to not do it again. Nevertheless, the guy liked the bike and didn't found anything wrong with it.)

[Eric Estlund]

How small are you talking? Smaller wheels are always an option.

[Curt Goodrich]

Very general rule of thumb- As the bike gets smaller the seat angle gets steeper, the head angle gets slacker and fork rake increases. This keeps the front center within the normal range.

[blasdelf]

As the bike gets smaller the seat angle gets steeper

why bother when you're designing a bike for an actual person and not for a marketable size chart?

the front-center is the front-center, the reach is the reach, the STA affects neither

[Curt Goodrich]

why bother when you're designing a bike for an actual person and not for a marketable size chart?

the front-center is the front-center, the reach is the reach, the STA affects neither

I disagree but you are always welcome to build your bikes the way you wish. Your quote missed my first five words which are pertinent.
Rule of thumb - Wikipedia, the free encyclopedia

[steve garro]

why bother when you're designing a bike for an actual person and not for a marketable size chart?

the front-center is the front-center, the reach is the reach, the STA affects neither

Actually, with a fixed top tube length as you increase the ST* the front center increases.
CG knows a thing or two about building frames.
- Garro.

[Gattonero]

Also, for small riders 170 or 165mm cranks may help a little

[Zimmermanbicycle]

Smaller wheels are a real help as are cranks of the correct size but so much is dependent on the rider and the style of bike you plan to build.
-Eric

[e-RICHIE]

This thread is a good example of that classic NY cartoon atmo -

[drwelby]

Actually, with a fixed top tube length as you increase the ST* the front center increases.

Why would you fix the top tube length?

[e-RICHIE]

Why would you fix the top tube length?

You wouldn't atmo. I am sure he means with a given top tube length, etc etc.

[blasdelf]

You wouldn't atmo. I am sure he means with a given top tube length, etc etc.

do you let your clients give you a downtube length?


the top tube is the least meaningful measurement of a bicycle atmo

industry designerbros fuck around with the STA to make their size charts look progressive

but without actually moving the wheels around since that would really fuck shit up (instead of just constraining saddle choice)


https://www.flickr.com/photos/jimmythefly/6326849846/

custom bikes should be an escape valve from this nonsense, not a reinforcement of it

[e-RICHIE]

do you let your clients give you a downtube length?


the top tube is the least meaningful measurement of a bicycle atmo

Any measurement alone has no meaning atmo.

industry designerbros fuck around with the STA to make their size charts look progressive

Well let's all give them a collective Fuck You then huh.

but without actually moving the wheels around since that would really fuck shit up (instead of just constraining saddle choice)

I did not know that.

custom bikes should be an escape valve from this nonsense, not a reinforcement of it

Some valves leak.

[Gattonero]

I see the above as a red herring.
the OP is "how a bike has to be sized correctly to avoid toe overlap".

Since anyone has different body measurements, sometimes a "standard" geometry fits well, and sometimes it doesn't. That's where the good framebuilder fits in.

As a mechanic, IMHO any road frame <50cm ST that is not meant for proper racing, should have 650b wheels. This solves lots of problems like gear ratios, clearance between brakes/handlebars, etc.

[Jonathan]

Fred,
I don't know if you're trying so hard to win an argument that you're missing the obvious, or if this can be a teachable moment for you( I suspect both). The diagram above has nothing to do with how we design bikes that are made to measure or how the OP can make his frame work for him. I don't think it even represents how bike designers in industry do things but I only know a couple and we are not them anyway.

[drwelby]

The diagram above has nothing to do with how we design bikes that are made to measure or how the OP can make his frame work for him.

Just for reference, who is this we you're speaking for?

[e-RICHIE]

That graphic makes my head hurt atmo. The 5 degree hypothetical change is mad painful.
Using it to explain anything here elicits only one comment from me: Who cares what they do!

[Jonathan]

Just for reference, who is this we you're speaking for?

People who charge money to do so. But ill add I don't speak for anyone but me.

[Mike Mcdermid]

Use toe cleats to move the feet back.....undustry std

[drwelby]

People who charge money to do so. But ill add I don't speak for anyone but me.

OK, I'm new here so I didn't know if you had a poll or there was some kind of questionnaire where you had to submit your P&Ls when you joined the club or collectivé or whateveur.