How straight does a frame been to be?

[Jezrant]

the 'gesture of goodwill' came from my erroneous assumption that the bike came from EB (sold secondhand maybe). Sorry, I misunderstood Southcraven. It wasn't terribly clear. I wasn't implying anything untoward and sincerely hope nobody took it that way. I suggested he take the bike to Woodrup's because, as I stated above, they have taken over BJ's business.
BJ had their ups and downs over the years. They made some fine frames, and some less fine. And Hetchins. And good paint jobs. And very reasonable prices. It's a shame they had to close their doors after all those years.
Anyway, I'm sure the OP's issue will get sorted, hopefully it's just the dish.

[slowster]

Also on the subject of Brodie's alignment process it is flawed, which is why he gets confused flipping the frame on the alignment table.

I would be interested to learn how it is flawed - could you provide an explanation?

[rogerzilla]

Absolutely - Aside from the cost, unbrazing parts and re-doing them for a fraction of a mm is likely to cause more damage than it's worth

Ellis Briggs have form for unnecessary work. They like to change the brake bridge to reduce rear spacing, I believe. Everyone else just bends the rear triangle and tweaks the dropouts.

[gibbo1982]

Absolutely - Aside from the cost, unbrazing parts and re-doing them for a fraction of a mm is likely to cause more damage than it's worth

Ellis Briggs have form for unnecessary work. They like to change the brake bridge to reduce rear spacing, I believe. Everyone else just bends the rear triangle and tweaks the dropouts.

Andrew Puodziunas my predecessor had a word for those who cut corners, he called them cowboys.

Anyway you are incorrect, we've never done unnecessary work. But if you open the rear end for 120 to 130 for example, without fitting a new bridge, the seat stays bow and it looks like an amateur has done it. You can usually go from 126 to 130 without a bridge.

EB

[gibbo1982]

Also on the subject of Brodie's alignment process it is flawed, which is why he gets confused flipping the frame on the alignment table.

I would be interested to learn how it is flawed - could you provide an explanation?

Certainly.

In his demonstration of using a surface plate he attempts to use the centre plane of the frame but he has no accurate way of finding it which introduces error instead. This same error is transferred to the rear dropout spacing, so the dropouts end up offset. So when he flips it over, even though you can see the main tubes are still parallel to the table, there is a gap and the rear spacing is also in error. He then concludes its his table!

I have to admit that the table he use looks quite weedy but its easy check whether it is flat. The whole point of it is to give you a defined reference point. That way, if you follow the right procedure and you know your table is flat then the error is in the frame.

I use the surface table to check the main tubes are parallel to the table, and most importantly that there is no twist in the frame. Then the rear end is tracked using the frame as a reference so the wheel is on the centre plane of the frame with no tilt. Often frames are built with the chainstays or seatstays slightly too long throwing this out. Obviously in the old days when horizontal dropouts were used, there was some adjustment on the chainstays and it left the seatsays needing to be perfect (vertical ends can be filed to adjust the seatstay length but then the chainstays need to be spot on). Now its very difficult to achieve because thru axles have no leeway whatsoever.

The process is similar with the forks

In the end the aim is for the wheels to track perfectly. If you watch my video you can see that's the case.

I can't take any credit for the process, I didn't design it. It was designed nearly 90 years ago when we first started building frames, and we've used it ever since. Those guys knew what they were doing.

[pjclinch]

"Common sense" says you want everything in a perfect line.

My Burrows 8-Freight cargo bike doesn't even bother trying and has the rear wheel sat to one side of the main frame spar, so is several centimetres off-beam from the front. It doesn't really ride no-hands too well (!), but then with an 80 degree head angle and a 20" wheel on a dead-straight fork giving only marginally more than no steering trail at all, it's probably that more than the offset back wheel... The very long wheelbase will affect the end result, I imagine, but overall my takeaway is judge by the actual ride (actually fine on the 8-Freight unless you have rather silly loads on board) and not the ruler.

Pete.

[gibbo1982]

I think some missalignment is acceptable on factory made bikes, and a cargo bike designed to have an offset wheel is an extreme case and probably a compromise.

I read a study on wheelchairs where they tested wheel misalignment and they concluded that as you increase toe in or toe out of the wheel the rolling resistance increases exponentially. And just 1 deg of toe in or out produced a 25% increase in rolling resistance. I would say that was quite significant, especially at the speeds of average cyclist where aerodynamics has less of an impact

I really can't understand the excuses made for poor alignment, its perfectly achievable on a handmade frame with care and attention.

[KM2]

Ellis Briggs idea that the chainstays are of unequal length could easily be checked by measuring accurately.
The offset of the rear triangle to the front triangle could be measured using a piece of string from one dropout round the head tube to the other dropout. And measure the distance from seat tube to string.
I haven’t read all the information above, so I could be repeating someone else.

[531colin]

............And as for Orbit intentionally building frames out of alignment to decrease the amount of dish on the wheel! Wow. That just screams a BS excuse for not getting it right in the first place. ..........

Not at all.
Jigging up, instead of setting both the dropouts 67.5mm from the centre, the right dropout was set 71.5mm, and the left 63.5mm .
Wheels are built using a conventional dishing gauge with an 8mm spacer on the left locknut. (or in the frame, with a string line from the front wheel)
Obviously, the rim isn't central in the stays.

Having to hand offset and conventional frames and wheels, I couldn't resist having a bit of a play.
Mis-matched, that is an offset wheel in a conventional frame, or a conventional wheel in an offset frame, either combination rode no hands in a straight line just as long as you had the saddle under one cheek.

"southcraven" has a bike where the wheel is a whopping 1mm off centre at the chainstays, and apparently the wheel is good.
Personally, I would be looking elsewhere for the reason he can't ride it no hands.

[Brucey]

......Personally, I would be looking elsewhere for the reason he can't ride it no hands.

FWIW I agree. More often than not steering issues have their origins at the front, not the back.

[Keezx]

Last week I was involved in an accident with a car which came from the left and hit the rear part of my winterbike (heavy steel frame) pretty hard.
Fell in the grass, and no noticable injuries....lucky me.
At first look, only the tire was punctured and the bars not straight, the rest looked fine.
A friendly witness brought me home, where it turned out that the left seatstay was dented heavily inside , a lot more than the design of the manufacturer (no cracks though), so that the rear wheel lent over to the right appr. 1 degree.. alignment in length seems okay.
Decided to ride it to test if it still was a usable bike, and i did not notice any discrepancy in riding perception., compared with before.

[the snail]

I can't ride no hands on this bike, is that related?

No. A slight misalignment will make no difference whatsoever to the handling of the bike, it just means the handlebars will be slightly turned when you are travelling straight ahead. The wheel would be jammed against the frame before it got to an angle that noticeably affected the steering.

[CJ]

"Common sense" says you want everything in a perfect line.

My Burrows 8-Freight cargo bike doesn't even bother trying and has the rear wheel sat to one side of the main frame spar, so is several centimetres off-beam from the front. It doesn't really ride no-hands too well (!), but then with an 80 degree head angle and a 20" wheel on a dead-straight fork giving only marginally more than no steering trail at all, it's probably that more than the offset back wheel... The very long wheelbase will affect the end result, I imagine, but overall my takeaway is judge by the actual ride (actually fine on the 8-Freight unless you have rather silly loads on board) and not the ruler.

I thought Burrows designed the 8-freight's frame and fork so that one or other (perhaps both) of its wheels stood at a non-vertical angle to the road, so they tracked in-line despite being offset by several centimetres at the hub. What kind of straight-line tracks does this bike leave after going through a puddle on a dry road: two wavy lines side-by-side, or weaving symmetrically around one another, or something in-between that weaves loosely with only occasional and unequal crossings?

[CJ]

I read a study on wheelchairs where they tested wheel misalignment and they concluded that as you increase toe in or toe out of the wheel the rolling resistance increases exponentially. And just 1 deg of toe in or out produced a 25% increase in rolling resistance. I would say that was quite significant, especially at the speeds of average cyclist where aerodynamics has less of an impact.

That's very true and applies to any pair of wheels that run side-by-side, such as a two-wheeled bicycle trailer, the back wheels of a conventional 'delta' tricycle, front wheels of a 'tadpole' design such as the Trice, etc. Misalignment in that case causes tyre scrub, which not only increases drag but also tyre wear, and hugely. I used to advise Center Parks on cycle safety problems and rapid wear in the tyres on child trailers, that otherwise hardly wore at all (since they carried a small load and simply rolled without any drive or braking torque) was a tell-tale indicator of a bent axle. (All the evidence indicated that this was usually caused by guests unaccustomed to towing a trailer running the wheels into obstacles and/or overloading by grown-up-children having a lark!)

All that does not, however, tell us anything about wheels that run one behind the other with a self-aligning caster action. A bicycle is, in engineering fact, two casters with a common pivot, the front caster having a short trail so that it may be steered, while the rear has a very long trail and simply follows. The arrangement being self-aligning, scrub is minimal and occurs mainly when changing direction, around corners etc. Straight line rolling drag is not increased significantly when the two wheels follow separate parallel tracks - or not so long as the out-of-track separation remains a very small fraction of the wheelbase! So there's no need to worry that your slightly out-of-track bike will be harder work to ride.

[Brucey]

in my dictionary it says 'caster -person or thing that casts'

are you sure you don't mean 'castor' ?
(Although that is how Americans tend to spell it, bless 'em.....)