Toe Overlap on Charge Mixer

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Michael R
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Re: Toe Overlap on Charge Mixer

Postby Michael R » 10 Jul 2011, 8:32am

mark a. wrote:Negligence by the bike company, or incompetence by the rider?

I bet more people have hurt themselves by flying over the handlebars than having toe overlap issues (especially as TO problems tend to be at low speeds), yet I haven't heard of any bike manufacturers being sued for putting strong front brakes on their bike.


Well that means you cannot use a bike at low speeds in town and traffic or on narrow lanes when you might need to make sharp turns at slow speeds.

The Cube I had for a day was unsuitable and dangerous both in town and on country lanes.

How do you power round a very sharp bend going uphill (steep) to join another road? I do this often round where I live and have to slow to 5 mph select a low gear and as I pedal turn sharply to the left . With TO I would hit the wheel with great force and grind to a halt if not on the tarmac. That is just one example. I could give a long list of examples within a few miles of my house.

A bike designed with a bit of intelleignece would avoid these problems

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Mick F
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Re: Toe Overlap on Charge Mixer

Postby Mick F » 10 Jul 2011, 9:31am

Michael R wrote:A bike designed with a bit of intelleignece would avoid these problems
Yes, but what we have is that most bikes on sale these days haven't been "designed", rather they've been concocted from the stylist's parts bin.

Take Patrick's bike for instance. Why does he have 175mm cranks?
He has them because that's what the chainset came with, not because he needs long cranks.
(Not picking on Patrick's bike, just using it as an example, I'm sure it's a lovely bike, and one I'll be seeing soon.)

There's nothing wrong with longer cranks, but I understand that crank length should ideally be matched to leg length.
Mick F. Cornwall

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patricktaylor
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Re: Toe Overlap on Charge Mixer

Postby patricktaylor » 10 Jul 2011, 11:04am

Mick F wrote:
Michael R wrote:A bike designed with a bit of intelleignece would avoid these problems
Yes, but what we have is that most bikes on sale these days haven't been "designed", rather they've been concocted from the stylist's parts bin.

Take Patrick's bike for instance. Why does he have 175mm cranks?
He has them because that's what the chainset came with, not because he needs long cranks ...

[my bold]

Actually Mick, the distance from BB C/L to ground on my tourer with 175mm cranks is 285mm. My son's Specialized Secteur road bike (not a tourer but with triple chainset) also has 175mm cranks but is only 275mm from BB to ground. So it seems we have 175mm cranks because we have triple chainsets, and the Ridgeback's designer has made allowance in the ground clearance - not the case with the Specialized which is also available with only two chainrings, presumably 170mm cranks, and unchanged frame geometry.

I think there is a view that tourers benefit from longer cranks.

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531colin
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Re: Toe Overlap on Charge Mixer

Postby 531colin » 10 Jul 2011, 11:56am

patricktaylor wrote:.........................I think there is a view that tourers benefit from longer cranks.


Not a view that I can identify with, I'm afraid.

patricktaylor wrote:............... So it seems we have 175mm cranks because we have triple chainsets, ......


Single, double, and triple chainsets come with comparable ranges of crank lengths.

Using the same crank length across a range of sizes is just another example of laziness. (175mm is the current fashion...too long for anybody with less than about 33" trouser leg, in my view.)
Crank length needs to vary with leg length....I'm Mr average, 31" trouser, its 170mm for me. 175mm pulls the back of my knees. (And yes, I found that out the hard way, by jumping on a mass-market bike and just riding it....a lot of pain later, after trying every combination of alterations to saddle position I could think of, I happened to see the length stamped on the back of the crank.....)
It really isn't difficult to fit different length cranks to different size bikes. All you need to keep an eye on from the design point of view is front centres (for toe overlap) and BB drop. (BB height is a function of tyre size and BB drop....frame designers control 1 of those 2 variables......more variables if somebody fits a non-standard fork....)

Still, in a world where frame designers use the same fork offset for a range of head angles, and produce bikes for the "leisure" market with overlap and steep angles, I suppose its relatively cheap and easy to replace the crankset.

EDIT

:idea: WELL, HATS OFF TO SPECIALISED :idea: .......here http://www.specialized.com/us/en/bc/SBCProduct.jsp?spid=52884&scid=1001&scname=Road
They list different crank lengths, front centres and BB drop for different sizes. (in the Geometry table)
SPEC. can do it.......will others follow?

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Mick F
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Re: Toe Overlap on Charge Mixer

Postby Mick F » 10 Jul 2011, 1:11pm

531colin wrote:SPEC. can do it.......will others follow?
I doubt it.
If you specify a certain dimension away from the stock item, it may cost you more, then again a supplier worth his salt would allow a change. This doesn't alter the fact that "designers" don't design in the old-fashioned sense any more.

LBS is one thing, but on-line shops are another.

I found this site.
Some interesting reading, but TBH I didn't read every word.
http://www.nettally.com/palmk/crankset.html

L(mm) = 5.48 x I(in)
Gives me 169.88mm
Mick F. Cornwall

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531colin
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Re: Toe Overlap on Charge Mixer

Postby 531colin » 10 Jul 2011, 2:24pm

first go at posting photos, didn't work!
got there in the end, though!
Last edited by 531colin on 10 Jul 2011, 3:37pm, edited 1 time in total.

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531colin
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Re: Toe Overlap on Charge Mixer

Postby 531colin » 10 Jul 2011, 3:27pm

Here are photos of toe clearance on Spa's Ti bikes. Mudguards removed for clarity.

These are the smallest 700c wheel tourer, and the smallest audax. The 54cm audax, if fitted with 170mm cranks (recommended), will have the same clearance as the 52 audax with 165mm cranks....all other bikes will have more clearance, if fitted with the recommended length cranks.

I maintain you can have toe clearance as well as acceptable top tube length and good handling characteristics.

Image

51cm tourer, 610 front centres, 32mm Marathon tyre, 165mm crank, clearance measured at 22mm.

Image

52cm audax, 595 front centres, 25mm Durano tyre, 165mm crank, clearance measured at 13mm.

Image

Shimano size 42 MTB shoe, toe end to cleat centre is a shade over 100mm.
Last edited by 531colin on 22 Jul 2011, 7:36am, edited 1 time in total.

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Mick F
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Re: Toe Overlap on Charge Mixer

Postby Mick F » 10 Jul 2011, 7:52pm

Thanks 531colin.
Good photographs, and good info.

+1
Mick F. Cornwall

drossall
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Re: Toe Overlap on Charge Mixer

Postby drossall » 10 Jul 2011, 9:28pm

Michael R wrote:How do you power round a very sharp bend going uphill (steep) to join another road?

I don't think I've ever come across a situation where I would turn the wheel enough to notice overlap in normal riding like that. It's usually when virtually stopped and moving the wheel around to maintain some kind of balance.

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Re: Toe Overlap on Charge Mixer

Postby niggle » 10 Jul 2011, 9:38pm

Mick F wrote:
531colin wrote:SPEC. can do it.......will others follow?
I doubt it.
If you specify a certain dimension away from the stock item, it may cost you more, then again a supplier worth his salt would allow a change. This doesn't alter the fact that "designers" don't design in the old-fashioned sense any more.

LBS is one thing, but on-line shops are another.

I found this site.
Some interesting reading, but TBH I didn't read every word.
http://www.nettally.com/palmk/crankset.html

L(mm) = 5.48 x I(in)
Gives me 169.88mm

I get 158.76mm with my little legs :oops: , which actually sounds quite sensible, so I should rush out and replace my cranks on both my bikes (all 170mm) with 160mm, but I am not going to as it will cost not only for them (how much for a road triple, or a single chainring set-up, in 160mm, assuming they even exist?) but for altering the gearing to suit, plus I am used to 170 anyway.

Michael R
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Re: Toe Overlap on Charge Mixer

Postby Michael R » 10 Jul 2011, 9:39pm

Mick F wrote:Thanks 531colin.
Good photographs, and good info.

+1


Why can't other manufacturers do the same ?

I went out for 4 hours in the South Lakes today and would have come a cropper with toe overlap.

To repeat myself ( and I may annoy some) this is a serious safety issue

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Re: Toe Overlap on Charge Mixer

Postby reohn2 » 10 Jul 2011, 10:58pm

Michael R wrote:
Mick F wrote:Thanks 531colin.
Good photographs, and good info.

+1


Why can't other manufacturers do the same ?

I went out for 4 hours in the South Lakes today and would have come a cropper with toe overlap.

To repeat myself ( and I may annoy some) this is a serious safety issue


It doesn't annoy me Mchael,I think you're spot on! especially on a touring bike where theres more chance of very slow climbing due to the load carried, when theres more chance of it causing problem.
But hey! its beyond some manufacturers to see the wisdom of slack seat tube angles too, which only goes to prove that race bike geometry prevails no matter what the intended use :?
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patricktaylor
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Re: Toe Overlap on Charge Mixer

Postby patricktaylor » 10 Jul 2011, 11:05pm

drossall wrote:
Michael R wrote:How do you power round a very sharp bend going uphill (steep) to join another road?

I don't think I've ever come across a situation where I would turn the wheel enough to notice overlap in normal riding like that. It's usually when virtually stopped and moving the wheel around to maintain some kind of balance.

Ditto.

I've ridden some 15,000+ miles on my toe-overlapping tourer and never once kicked my front mudguard while on the road, included fully loaded up wobbly hills. My wife has one too and she's never mentioned it ever. It's only an issue (and a slight one at that) in the driveway or maneuvering through the garden gate.

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Re: Toe Overlap on Charge Mixer

Postby niggle » 11 Jul 2011, 12:05am

niggle wrote:rush out and replace my cranks on both my bikes (all 170mm) with 160mm, but I am not going to as it will cost not only for them (how much for a road triple, or a single chainring set-up, in 160mm, assuming they even exist?)

Closest I can find for the road bike is a 105 triple chainset with 165mm cranks, £120. Quite a lot to pay for 5mm extra clearance IMO

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Mick F
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Re: Toe Overlap on Charge Mixer

Postby Mick F » 11 Jul 2011, 7:30am

This goes back to what I was saying about "design". You have to buy what is available, not what you want/need. We are all at the mercy of the marketeers and standardisation.

I've always had 170mm cranks, that's what came on the bikes, and I'm used to them - as most of are. Luckily, 170mm is right for me.
Mick F. Cornwall