Small frames: high trail or toe overlap?

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.)

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

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.

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Originally Posted by Curt Goodrich

As the bike gets smaller the seat angle gets steeper

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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

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Originally Posted by blasdelf

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

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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

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Originally Posted by blasdelf

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

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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.

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

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

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



https://farm8.staticflickr.com/7164/...6b74d3ac_z.jpg

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Originally Posted by steve garro

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

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Why would you fix the top tube length?

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Originally Posted by drwelby

Why would you fix the top tube length?

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

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Originally Posted by e-RICHIE

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

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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)

http://www.biketinker.com/wp-content...ly-bikegeo.gif
https://www.flickr.com/photos/jimmythefly/6326849846/

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

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Originally Posted by blasdelf

do you let your clients give you a downtube length?


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

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Any measurement alone has no meaning atmo.

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

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

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

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I did not know that.

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

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Some valves leak.

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.

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.

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Originally Posted by Jonathan

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.

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

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!

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Originally Posted by drwelby

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

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

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

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Originally Posted by Jonathan

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

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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.

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Originally Posted by drwelby

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.

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Huh? What?

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Originally Posted by e-RICHIE

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

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Yes.
Thanks for the proper wording.
- Garro.

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Originally Posted by blasdelf

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)


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

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I'm not buiding bikes I'm building A bike.
And yes, you do need to know the given length of a tube to make a bike.
How else would you cut it?
Customer's don't give me any lengths - how could they?
I'm the bike builder.
I'm not going to tell the chef how to cook…..

Doyouevenbuildbikesbro?

- Garro.

This all is getting to sound like Vincent Vega's first encounter with mayonnaise.

You mean a Royal with Cheese?

(saw recently Tarantino's Django, S. L Jackson reminded me of that)

Damn, I forgot I was with the pros here.

Was that Chili Palmer?

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Originally Posted by Gattonero

You mean a Royal with Cheese?

(saw recently Tarantino's Django, S. L Jackson reminded me of that)

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Originally Posted by Gattonero

You mean a Royal with Cheese?

(saw recently Tarantino's Django, S. L Jackson reminded me of that)

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Royal(e)

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Originally Posted by 11.4

Damn, I forgot I was with the pros here.

Was that Chili Palmer?

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Vincent Vega!
(we're drifting a bit, are we?)

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Originally Posted by Will Neide

Royal(e)

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Damn, I forgot I was with the pros here who nitpick.

I think Gatty has it right, anyway. I was thinking about Chili Palmer.

I think it must have been a John Travolta fascination with European McDonalds, since Get Shorty was an Elmore Leonard movie, not Tarantino, as I recall. Have to go back and check Saturday Night Fever to see if there was a Macdonalds in that one too. There is in Staying Alive. Hmmm.

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Originally Posted by Gattonero

Vincent Vega!
(we're drifting a bit, are we?)

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Yeah, but it was either that or more oscillating seat tubes.

Back to you, sir.

The best solution to solve most small frame problems is to use smaller wheels. I don’t get why there is such reluctance to make this obvious choice. Besides resolving the toe clearance problem, it makes the frame look more proportional because the top and down tube aren’t jammed so close together. On smaller frames, 650C wheels don’t look small but normal.

It is possible that a shorter recreational cyclist requires a 74º seat angle (that will help get toe clearance with 700C wheels) but not probable unless they like a deep handlebar drop. I’ve built a lot of custom frames for women and many prefer to have their handlebars nearer the height of their seat to take saddle pressure off of their sensitive crotch area. This body rotation upwards pushes their saddle (and therefore the seat angle) further back. As people age and they aren’t so skinny and flexible anymore they like higher handlebars too. This makes a shallow seat angle much more likely (and front wheel clearance less likely). Adding fenders makes clearance nearly impossible.

Let me explain how I start to build a custom frame. 1st I do a fitting based off of their present bicycle position. Often times this position has been compromised if they are smaller or larger than average because it has been forced into whatever production frame they bought. I do this on a fitting bicycle that has plenty of adjustment. I’m likely to find that the amount of saddle setback that provides butt/hand balance (that just takes the pressure off of their hands) is further back then whatever they are riding now. It is almost certainly less than what is required to get a 700C wheel front center out far enough for toe clearance. Only when the refined handlebar/seat/pedal relationship is known can I design/build the frame around those points. This is the advantage of a custom frame (that we build the frame to fit the person’s contact points and not force the person to fit the frame).

So there is an easy solution to make all aspects of a small frame work the best – use 650C (571 bead diameter) or MTB (559 bead diameter) wheels. Actually it is possible to use 650C with 39/49 mm brakes and at the same brake hole distance 47/57 mm brakes on MTB rims. The problem with 650B wheels is that they are fatter tires that makes their diameter similar to a 700C tire so not much (if any) clearance is really gained.

I hear all sort of resistances to using smaller wheels but I think it mainly involves reluctance to being different than normal. All frame design involves some kind of compromise and I consider wheel/tire convenience to be a much lower priority than the most advantageous frame design.

Racer types aren’t as concerned about toe clearance. They turn by leaning. However if your slower ridding companion does a uie and sprawls in the road because her foot hit her front wheel, she will think you are a bicycle frame design idiot and she would be right.

That's what I've said before.
I do not put together "off the shelf" bikes, and especially now the market for winter/audax/touring bikes is N times bigger than before. Lots of people asks for this sort of bikes, and their type of use involves mudguards and hardly if any toe-overlap. On top of the difference in the way the bikes go around the corners, there is also the gear ratio: is only a recent thing that road RD's can support a 30t or 32t rear sprocket. So most of the small riders can benefit from smaller wheels without having to go for a triple chainset or silly big sprockets on the back.
For the 650b size there's good choice of rims (Velocity, Sun, Mavic) and tyres (Schwalbe, Conti, Panaracer), not as much as 700c but still ok

This. Smaller people need smaller wheels, it was true in the days of Penny Farthings and it's just as true now. I've just finished repairing a lovely Rivendell that belongs to a smaller woman, and it's still perfectly proportioned as it has 559 wheels. So much better than the 622-wheeled bikes which end up with a tiny head tube and lots of toe overlap.

My perhaps controversial opinion is that no toe overlap is acceptable on a bike that is intended for road use.

At the risk of having the thread turn left, I'll add that this focus on toes touching wheels thing, and thus designing to avoid it, is one that's never made my radar. I make bicycles for folks who know how to ride, or should. I assume as much when they arrive at my door. This isn't Intro To Riding A Bike we have going here atmo. If anyone has a problem at such a low speed, or at such a low speed on a hill so steep that the turned wheel would hit the toe and cause worry, I'm not sure who from among the others to send them to. But maybe I'll start that list today after the World Cup.

mr. Sachs, with all the respect, you do Cx and road frames.
People who lives in a big town where it rain, and have to do 85 stop/start and do need mudguards, they do get very annoyed by toe-overlap.

I do use a road bike with clip-on full guards, and yes I do get overlap. I can live with it, but don't assume everyone does in every situation. If I had a light-touring bike, having my toes overlapping 5cm my front mudguard, I'm sure that will get me annoyed. On my Pego or SC I cannot care less about toe-overlap

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Originally Posted by Gattonero

mr. Sachs, with all the respect, you do Cx and road frames.
People who lives in a big town where it rain, and have to do 85 stop/start and do need mudguards, they do get very annoyed by toe-overlap.

I do use a road bike with clip-on full guards, and yes I do get overlap. I can live with it, but don't assume everyone does in every situation. If I had a light-touring bike, having my toes overlapping 5cm my front mudguard, I'm sure that will get me annoyed. On my Pego or SC I cannot care less about toe-overlap

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I can accept the reply and the commuting/commuter's example. Thanks. That has to be the outlier example here though, no? For the bigger tires and the added fenders, I'd guess the front center needs at least 2-3 more centimeters for clearance. I get the small wheel option, but otherwise can't speak to a small frame with such a long front measurement just to avoid the contact.

I guess this is one of those things where different builders cater to very different markets - I build almost no racing bikes (repair them though), I build mostly commuters, tourers and MTB. For those applications, toe overlap is a big no-no.

For commuter/city use, there's also the option of taking a hard look at flat bars.

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Originally Posted by bencooper

I guess this is one of those things where different builders cater to very different markets - I build almost no racing bikes (repair them though), I build mostly commuters, tourers and MTB. For those applications, toe overlap is a big no-no.

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Then we go back to the OP again - in your line of work, is the trail he mentioned acceptable atmo? He was asking about road frames after all irc.

I still think a better solution is to scale everything down - smaller wheels, smaller cranks etc. Sure, expert roadies will cope with toe overlap, but it's still not an ideal solution.