Ross McArthur

Eccentric Dropouts.

61 posts in this topic

i should have said "bigger" instead of big.

what i wanted to say is that the range of the possible positions of the axle shouldn't be bigger than the range of psitions dictated by the brake mounts, so that you don't make the cams bigger than they should be. hope it makes sense..

btw, do you think the cams made by him would work? (since i don't intend on specially building myself a set of cams)

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I had to think about the quick release squer space on the cam. If you have a 5mm bolt to hold the wheel in then I suppose you could go for a smaller cam yea.

Marino redesigned my proposal with smaller dropouts, 20mm dia but as I said I need the space for my QR.

Marino will make your cams, he made mine but mine are more "bling" lol.

Eccentric dropouts for the ultimate win! (I hope)

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I had to think about the quick release squer space on the cam. If you have a 5mm bolt to hold the wheel in then I suppose you could go for a smaller cam yea.

Marino redesigned my proposal with smaller dropouts, 20mm dia but as I said I need the space for my QR.

Marino will make your cams, he made mine but mine are more "bling" lol.

Eccentric dropouts for the ultimate win! (I hope)

i do have 5mm bolts for it (trialtech hub)

cool, i think i'll give it a go! (not for my trials frame, but for a commuting frame made for a more trick oriented way of getting 'round, basicaly a fgfs bike but with a fw and at least 1 brake)

hope to see your bike build up soon.

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On 15/09/2010 at 8:39 PM, Ross McArthur said:

:rolleyes:

 

 

Quite a bump, but... How did this work out?

I'm pondering dropouts for my new (SS MTB) frame and considering eccentric. Cheers!

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On ‎09‎/‎01‎/‎2021 at 5:26 PM, Adam@TartyBikes said:

Quite a bump, but... How did this work out?

I'm pondering dropouts for my new (SS MTB) frame and considering eccentric. Cheers!

No worries. So, other than changing the geometry depending on what gear ratio I ran, and forever fearing a puncture because I'd have to take it all to bits and reset it again, it was great! The clamp on the cams was tight enough for it never to move, it was near enough equal in weight (alloy cams) to having a small tensioner.

Like I say, setting it up wasn't the easiest. I'd have to use a screwdriver to push the cam round and was a wee bit fiddly but I'm sure a man of your calibre wont struggle too much. It would have been easier if the cams were greased but then there would be a chance of them slipping so ran them dry.

Marino done a great job of making sure the rim brake mounts lined up but I'm not sure how it would work with a disc with that amount of adjustability/movement in the tensioning of the chain..

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Awesome. Thanks a lot for the info!

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Imo, I think eccentric probably works better in the bottom bracket. That way you only have one cam doing the tensioning.

The drop outs were fiddly because you had to centre the wheel between the chain stays, and with a chunky rear tyre and not much clearance with a super short rear end, 26" wheels in a steel frame...

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A similar system was used by transition on its dirt bike (the bank). One friend had one and he had the same issue as you described:difficult to adjust or the system was slipping. They abandonned this solution very quickly.

There are also some excentric bottom brackets for BSA frames. Trickstuff oder Philwood are producing some. Not sure it will survive the abuse of trials, but it is used on some singlespeed bikes. It will reduce your crank choice, but the 24mm steel axle is the only one well desgined though ;)

There is also the ENO excentric hub ...

 

With an exentric bottom bracket, one can imagine to reduce the bottom bracket cage section in its middle so that you get more space to shorten the chainstay. Like this:

fullfrontebb__62777.1520018993.JPG?c=2

 

Edited by La Bourde

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Thanks for your input guys!

I also think eccentric BB would be easier for adjustment - though in considering this, it has made me ponder why the eccentric system at the dropouts is awkward. Yes you can move the wheel around, but only on a prescribed circle. You can't just nudge it directly up a bit here, or horizontally back a bit there, for example.

So, I've come up with something else that may or may not work, we'll find out in a few weeks :lol:

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Just remembered I had this clip of Marino testing the set up.

 

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Thanks Ross, I think that's the same one as earlier in the thread?

I've ended up with a kind of semi horizontal dropout, so in theory you can just sit on the bike with the drive side wheel bolt loose, then tighten it up...

No close up photos on my phone but can maybe make them out here...

20210225_162055.thumb.jpg.57e3e95ed1d1fac45c17bb31c1ff6b59.jpg

Basically a neat, modernised version of oldskool road bike dropouts!

2018-02-26-004.jpg?ssl=1

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