Polo bike geometry + addons

I'm still really interested in geo for polo (and still think that LDN has the best knowledge).
Matt mentioned something about the cosmic bikes not nessarily going for the smallest wheelbase? Where I was under the impression the smaller the 'turnier'.
I gather Ryan doesn't think curved seat posts are better. But having the seat over the rear wheel gives better manoeuvrability?
What's the ideal trail?
And BB height?

I know these are all variable depending on many factors, but if you wanted to draw up your own bike, are you just looking for it to be as tight and sturdy as possible?

I appreciate also there isn't a succinct answer, but it's good to chat innit.
#missesLPC

I think it's trying to find the balance between maneuverability and stability. Although it's great to have a bike which is good in the tight scrappy corners where it's all fairly low speed you also need something that gives you confidence on the break.

Hi London, Constant from Brussels bike polo
We're trying to build some frames from here with a frame builder who looks professional and not too expensive.
We worked on a geometry with the help of Marvin from US, I think that will be close to the last one Todd and Mat have designed. I really like the explanations on the posts they made on their blog.
I saw some geometry on the 14bike website but it looks like being the old version.
Is there a place where we can find this geo ? On Bikecad or somewhere else ?
Thank you, it could be great help for us !

Shouldn't you be working out your own geo instead of stealing other people's?
#justsayin

ha ha, ok thanks for your point of view.
If sharing geo and asking some advices is seen as stealing, that's a point of view.
We're not in that business here in Brussels, just a small community of 15 players sharing informations between each others, no sponsors etc..
We approach frame building in a more open source way, like cooking recipes we share with other people, i believe that tools like bikecad or github are good places to post bike geometries.
Things are going fast in the polo universe, the question is more in what kind of world you want to play.

#justsayin

popcorn

Zing.

I think joe just got pwned.

#contextualstudy

Ha! Stealing was too strong a word... ;)
Do you know what you want your new bikes to do? It's all very well taking pointers from what other people have done but you may just wind up with something that doesn't work/suit your game... Anyway, good luck with it!
#stilljustsayin #bikegeoisallsorcery

Zing.

I think joe just got pwned.

#contextualstudy

Straight up pwned

pwn9ed you could even say.

Jimmy (Citygent) has just had quite alot of back and forth with 14 about geometry, maybe ask him? There is a bit of a difference between taking the geo from 14 who are trying to make money from selling that design and some of the bikes which started off as a more community based thing, but only if you fucking love capitalism.

Here is my project of 26" polo bike, any advice about it?

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Make the frame lines thicker so you can actually see them?

:)

The 'bad' polo geo is freely available. I'd suggest asking cosmic or 14bike themselves if they are going to make the 'cosmic' geo avails.

I'm not sure what jimmy changed. Cam changed some things on his 14 too.

Preview

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One thing I've been wondering recently is what's the logic behind the length of seattube?

Obviously there's limits to how long a seatpost can be, but within that, why not go for a horizontal top tube (most I've seen recently have been sloping) and if sloping is good, why not go as far as bmx/trails bikes and have almost no seattube?

In polo you are on your saddle more often. Hence, bmx/trials ≠ bike polo. IIRC most trials bikes are not fitted with a saddle because the riders spend most time balancing themselves upright.

Here are the one we're working on.
The yellow one was the first one made by the great Marvin, which is a very nice project, the black one is an adaptation made by Vincent from Brussels, with a shorter wheelbase (I'm afraid this one has a lack of clearance ??).
And when I read the post on the Cosmic blog, I was wondering if we maybe can make some improvements following their geometries.
Actually, I'm a bit lost in term of wheelbase and clearence, afraid to build a frame with toe overlap, or too hard to ride.

By the way, 14bike usually post their frames geometries on their blog, and they don't seem to put copyright logo everywhere on their webpage. For me their 'savoir faire' is somewhere else, not a problem and the idea is not to make a copy paste. http://www.14bikeco.com/frames-forks/14-polo-bike-v-3.html

Anyway, thanks for you answers.

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Ben I'm aware of what I like as distances between saddle and pedals, my question is what percentage of that distance should be seattube and what should be seatpost?

Without knowing anything about building frames, as I understand it:

The longer the seatpost (and therefore shorter the seattube), the more torque you are applying to the seatcluster. So the longer you make it, the more risk of snapping the seatpost or damaging the seatcluster.

But the advantage is the shorter the seattube, the stiffer the frame will get, and of course a marginal weightloss, from having less tubing.

Constant:
I saw a 36 cm basis on Todd's bike too. there is no problem between tyre and seat tube white that? not too short?
Otherwise it looks nice. The trail on this bike is same as todd and i like it a lot.

About sloppey, i really like to ride sloppey bike, you get rid of this fucking top tube who just want to kick you knees every time you try to rotate while jumping. Also you get loose some weight.

Without knowing anything about building frames, as I understand it:

The longer the seatpost (and therefore shorter the seattube), the more torque you are applying to the seatcluster. So the longer you make it, the more risk of snapping the seatpost or damaging the seatcluster.

But the advantage is the shorter the seattube, the stiffer the frame will get, and of course a marginal weightloss, from having less tubing.

This. It's why a lot of road frames are now using the compact design.

There's the obvious limiting factor of the seatpost length. I've designed mine for a 350mm to be on the max when I use it. I also tried to work out how low it would have to be for the brake lever to avoid the top tube if I jackknife.

Here's my geo - https://www.lfgss.com/attachments/59379d1349475325-line.png
Front triangle is built, just waiting on some material for the dropouts and it can be finished. I'm a little worried about the wheelbase, but as I'm making the frame out of some scrap it's not too much of a worry. If this geometry does work I intend on sending it to Mielec for them to make it.

Hi Constant,

This is a bitof a brainfart but I hope it helps

I was running a 69mm trail on a longer wheelbase jumpbike (420mm CS, 590mm F-c) and it felt nice cornering but the steering was heavy. I didn't want to add any more trail as I didn't want to make it feel any heavier.

When I had my own frame built I lifted the front end geometry (69mm trail and 74 deg headangle) and shortened the rest of the frame a lot.

With all the extra weight on the rear wheel of the new bike the front end would feel very light, understeer and be more prone to jack-knifing early.

I was running an adjustable length fork for messing with headangle and trail, so I spaced it from 74deg out to 73deg w/ 20mm Rake on a 642mm OD wheel. This has added a bunch of trail and the bike rode so much better for it.

I then got a Maxpower fork with it's 10mm rake so I can mimic the same trail with the steeper 74deg headangle.

I suggest those bikes above will have light steering and jack-knife early due to not enough trail.

A simplistic explanation for polo frames:
The headangle dictates how well the bike will ride at low speed. (it changes the speed of steering inversion)
The trail dictates at what point the bike will jack-knife.

If you're small then get your fit correct and your trail to a reasonable number and let the headangle be where it needs to be. Loss of low speed stability can be corrected by rider skill but a badly fitting frame cannot.

Also those frames both have quite long front-centres. I can run 560mm F-c with 170mm cranks and 642mm OD tyres. I have overlap if I point my toe, but when I'm riding hard I drop my heels anyway so it's never caused a problem.

One more thing, if you're ordering from Marino try to have some reasonable tolerances to all your clearances as it probably won't turn up quite as ordered.

But the advantage is the shorter the seattube, the stiffer the frame will get, and of course a marginal weightloss, from having less tubing.
mitigated by the fact that you have your seatpost, a large unsupported piece of tubing flexing back and forth.

Ha!

...One more thing, if you're ordering from Marino try to have some reasonable tolerances to all your clearances as it probably won't turn up quite as ordered.
...

Constant:
I saw a 36 cm basis on Todd's bike too. there is no problem between tyre and seat tube white that? not too short?

With a 360mm chainstay length you can get a 1.9" tyre in there. If the frame has a larger diameter seat tube you may be limited to 1.75" which is still big enough. I think the hardest bit with short chainstay lengths is keeping the strengths in the chainstay while still having space for the tyre and the chainrings. I believe this is why a 73mm BB was used on Emyr's BTR.

http://www.bikecad.ca/1359478872528

My design. 26" wheel. 1.5" vittoria rubino pros, they are great tyres, but on narrow rims they are rather tall.

Wheel diameter measured from flat floor to axle centre 325mm. I imagine this is the most accurate way to measure

It has a lower BB than most would like, I use spd's so pedal strike is less likely and I prefer the stability from the low centre of gravity.

60 or so trail seems to be good to aim for. I'm using 30mm rake Echo urban forks with a 74degree HT.

front to centre measured to fit SPD size 12 with 175mm xtr cranks with a cm or so spare.

Just question bout 26" forks.
Will you guys design a bike about a specific fork with a shorter a-c distance (as some marinos, max power and RC and probably 14 get) than the one you find in the market?
This make that you can make you geometry around a fork who is around 365 mmheight (like the mp :http://www.maxpowercycles.de/forks/ ) or around someting bigger that you can find on rigid mtb fork or fixed freestyle one, more between 390 and 410 mm.

Im kind of lost. I think longer a-c distance is an advantage because you can get a more natural position whitout a too long head tube, raiser bar or spacers. Also it's maybe more convenient to make a frame around forks that you could find for cheap and more easily.