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Old 03-31-07, 03:26 AM   #1
man of calibre
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Does 135mm OLN affect Q-factor?

I am getting a frame custom built. The concept is to be a light tourer type thing: 'freeeroad' if you take Specialized terminology, 'Country bike' if you are a fan of Rivendell.

I am quite lightweight (60kg) so do not require really strong wheels but would like the reassurance of 135mm OLN for strength on rough roads, also because this width seems to be the standard for almost all non-road applications, and is used on modern hub gears like the SRAM iMotion and Dual Drive (not that I would use these on the bike I have in mind). My question concerns the effect that the choice of 135mm OLN would have on the Q-factor of the pedals. I understand that the narowest Q factor is to be found on chainsets based around road doubles and 'compact' doubles, with road triples being a little wider. Would I be able to use these as the manufacturer intended or would I have to have a long axle to get the chainline right?

I intend to have 435mm chainstays so am not concerned that heel clearance or clearance of the cranks on the chainstays will be a problem unless anyone can prove otherwise.
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Old 03-31-07, 03:45 AM   #2
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Originally Posted by man of calibre
I am getting a frame custom built. The concept is to be a light tourer type thing: 'freeeroad' if you take Specialized terminology, 'Country bike' if you are a fan of Rivendell.

I am quite lightweight (60kg) so do not require really strong wheels but would like the reassurance of 135mm OLN for strength on rough roads, also because this width seems to be the standard for almost all non-road applications, and is used on modern hub gears like the SRAM iMotion and Dual Drive (not that I would use these on the bike I have in mind). My question concerns the effect that the choice of 135mm OLN would have on the Q-factor of the pedals. I understand that the narowest Q factor is to be found on chainsets based around road doubles and 'compact' doubles, with road triples being a little wider. Would I be able to use these as the manufacturer intended or would I have to have a long axle to get the chainline right?

I intend to have 435mm chainstays so am not concerned that heel clearance or clearance of the cranks on the chainstays will be a problem unless anyone can prove otherwise.
I think I understand your problem (as a guy permanently looking for small Q-factor cranks). Q-factor actually a term introduced by the boss of Rivendell, if I recall correctly, and determines the position of the pedal in respect to the crank's ummmm interfacing point with the BB's spindle. (ok, I am sure many could blow holes in my "definition" but this is, more or less, what Q-factor is). The smaller the Q-factor, the less your feet are apart on the pedals. However, to determine how far your feet will be (relative to the bike's vertical axis) you also have to take into consideration the BB's spindle length, which can be 107, 110, 112, 117mm or anything else. Different lengths are used to accomodate different chainlines.

White Industries has a very nice SS/FG crankset with very low Q-factor. Sadly, I just can't afford that fancy piece of equipment.

EDIT: so basically, the OLD is significant only to the extent that it determines the chainline, and therefore, the BB's spindle length.
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Old 04-01-07, 12:18 PM   #3
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EDIT: so basically, the OLD is significant only to the extent that it determines the chainline, and therefore, the BB's spindle length.
Okay, but how much?

I have heard that MTB cranksets are quite offset in order to allow the rider to make use of the full range of the cassette whilst in the lower ring, due to the greater proportion of work that must be done in low ratio, and the desire of MTB riders not to have to constantly change between the 'granny' ring and middle ring whilst climbing. see this article on the subject. Intrestingly, whereas MTB triples have an offset of 47.5 - 50mm, road triples have an offset of 45mm. This seems to suggest that a road triple in conjunction with an MTB casette should be ideal - the difference in chainline is only 2.5mm, which read in conjunction with the MTB chainline being offset on purpose, would surely put the chainline in the right place for sporty riding?

As a matter of curiosity, is there any tangible advantage in the road 130mm spacing? The only thing that comes to mind is that I have been told is that the heel can catch on the chainstay of the wider spacing, but with only 2.5mm difference each side the likelihood of this being noticeable must be marginal...
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Old 04-01-07, 12:42 PM   #4
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Q-factor: http://www.sheldonbrown.com/bridgest...ne-1991-13.htm
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Old 04-01-07, 12:43 PM   #5
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Originally Posted by wroomwroomoops
=White Industries has a very nice SS/FG crankset with very low Q-factor. Sadly, I just can't afford that fancy piece of equipment.

EDIT: so basically, the OLD is significant only to the extent that it determines the chainline, and therefore, the BB's spindle length.
You're thinking too hard, many of the old square taper double cranks have really low q-factor compared to the modern garbage external bearing bling bling cranksets.

It's all the rage now to have flared out cranks with enormous q-factor even on doubles.
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Old 04-01-07, 02:23 PM   #6
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You're thinking too hard, many of the old square taper double cranks have really low q-factor compared to the modern garbage external bearing bling bling cranksets.

It's all the rage now to have flared out cranks with enormous q-factor even on doubles.
100% true, from the first word to the last.

I'll even give you the "you're thinking too hard"


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Originally Posted by operator
the modern garbage external bearing bling bling cranksets.
It's one of those advances in bike tech, that helps more the industry than the cyclist - those external bearing BBs last less than the classic ones, and just by not being compatible with square taper (these modern ones are octalink or ISIS) equipment, increase the amount of stuff people have to buy. I still have to be convinced that these splined interfaces are better than square taper.
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Old 04-01-07, 02:57 PM   #7
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Originally Posted by man of calibre
I am getting a frame custom built. The concept is to be a light tourer type thing: 'freeeroad' if you take Specialized terminology, 'Country bike' if you are a fan of Rivendell.

I am quite lightweight (60kg) so do not require really strong wheels but would like the reassurance of 135mm OLN for strength on rough roads, also because this width seems to be the standard for almost all non-road applications, and is used on modern hub gears like the SRAM iMotion and Dual Drive (not that I would use these on the bike I have in mind). My question concerns the effect that the choice of 135mm OLN would have on the Q-factor of the pedals. I understand that the narowest Q factor is to be found on chainsets based around road doubles and 'compact' doubles, with road triples being a little wider. Would I be able to use these as the manufacturer intended or would I have to have a long axle to get the chainline right?

I intend to have 435mm chainstays so am not concerned that heel clearance or clearance of the cranks on the chainstays will be a problem unless anyone can prove otherwise.
Sounds like something your frame builder should be able to discuss with you. You're paying a premium for a custom frame, ask questions.
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Old 04-01-07, 05:39 PM   #8
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Originally Posted by man of calibre
As a matter of curiosity, is there any tangible advantage in the road 130mm spacing? The only thing that comes to mind is that I have been told is that the heel can catch on the chainstay of the wider spacing, but with only 2.5mm difference each side the likelihood of this being noticeable must be marginal...
Heel catch could be a problem with wide dropout spacing if the chainstays are very short. Road bikes often have the chainstays as short as possible to get the rear wheel under the rider which shortens the wheelbase and quickens the handling. If you are building a touring frame with long chainstays, the wider dropout spacing won't cause problems as the wider part will be further behind your heels.
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Old 04-02-07, 04:28 PM   #9
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This page of that old Bridgestone catalogue mentions that 130mm rear (OLD) spacing is used on Bridgestone mountain bikes for chainline reasons but Bridgestone was run by a chap called Grant Petersen who is now main man at Rivendell. And Rivendell use 135mm rear spacing almost exclusively, and the bikes that don't use this spacing are 132.5mm to enable either 135 or 130mm hubs to be used. If Rivendell are now using wider spacing, under the management of the man who introduced us to the idea of Q factor, what gives?
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