FD Problem junior gearing

rtnicho
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FD Problem junior gearing

Postby rtnicho » Tue Feb 13, 2018 5:29 pm

I'm currently changing 50:34 chainrings (Shimano 6800) to 46:36 on a BMC to comply with junior gearing requirements (6 metre roll out). Even with the 50:34 on the 6800 FD sits 4mm above the chainwheel when the FD is as low as I can get it. With a 46 it will be a lot more than that. Weird shaped seat tube so can't convert to a band adaptor.

The last time I had this problem moving to 46:36 I bought a Shim CX70 (cyclocross) FD (for a Felt AR). Even after doing that the gap is still 6.3mm on the 46 (Also Shim 6800) chainwheel. So I'm not too keen on going down the CX70 path again. I can't go any bigger on the smallest cog on the cassette either!

In my travels I came across one of these: https://wickwerks.com/products/fit-link-adapter/
Apparently Sugino produces one as well.
Has anyone had experience with these? If so is there anywhere I can buy them in Australia and not pay big $ for postage?
Thanks in advance

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Duck!
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Re: FD Problem junior gearing

Postby Duck! » Tue Feb 13, 2018 7:04 pm

Sounds like you (well, Junior does) need a new frame. :-P
I had a thought, but it got run over as it crossed my mind.

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singlespeedscott
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Re: FD Problem junior gearing

Postby singlespeedscott » Tue Feb 13, 2018 7:56 pm

Weird you can’t get your derailleur down to the right gap with the cx70. I’ve had no issues with mine. Sounds more like your frame than the derailleur. Can you post some pics so we can see?
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Duck!
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Re: FD Problem junior gearing

Postby Duck! » Tue Feb 13, 2018 9:07 pm

Some frames that predate the widespread adoption of compacts have the braze-on mount located too high to be able to lower the FD enough to suit the smaller rings. Sometimes you can just file out the bottom of the slot to extend it down, but you do increase the risk of it cracking from the stress put through by the derailleur.
I had a thought, but it got run over as it crossed my mind.

ironhanglider
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Re: FD Problem junior gearing

Postby ironhanglider » Tue Feb 13, 2018 10:28 pm

Hi rtnicho,

You didn't say why it is not possible to use a bigger smallest cog, clearance issues?

If not:
It is possible to get a 16-27 10spd cassette which would allow you to use a 49T chainring.


If so:
CA permits blocking off
CA Technical Regs wrote:3.05.04 To restrict the roll out distance mentioned above, blocking off may be permitted by the adjustment of the derailleur or other means. There shall be no blocking off of gears allowed at U15, U17 or U19 Road National Championships. State Federations may determine if blocking off will be permitted at non-national championship events.


As does SACF
SA Cycling Federation wrote:Blocking gears

Please note that blocking off gears is not permissible in a State Championships. The only exception to this is that U/13 riders are permitted to block off.


So unless the young person is riding at Championship events it would be easier to just block off the smallest cogs and just have fewer gears.

Cheers,

Cameron
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RonK
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Re: FD Problem junior gearing

Postby RonK » Wed Feb 14, 2018 7:19 am

The postage is only $17.90, making the purchase less than $50.

For an item as rare and unusual as this you just have to bite the bullet and pay.
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rtnicho
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Re: FD Problem junior gearing

Postby rtnicho » Wed Feb 14, 2018 9:08 am

Thanks all

In response to ironhanglider one bike is currently running 46 x 16-27 (10 speed). With a 6 metre rollout 46 x 17 gives just under rollout so I block off 16 for non-state / national champs and use 2 17T cogs for other races. I suspect that this longer than expected rollout is because the tyres we use are 700x25 Conti GP 4000 SII which are quite a tall tyre, increasing roll out.

Yes it's definitely a problem with the frame (well both frames actually). It's not an issue with the FD hitting the chainstay, it's just that I can't physically get it down low enough. One frame (the BMC) is a 2013 model and the other (Felt AR) is 2015 model. I guess that as Duck suggested, the BMC predates the widespread use of compacts and because the Felt is an aero timetrialish-looking bike it just wasn't designed to run compacts let alone CX cranksets.

Thanks RonK. When I did the postage calculator thing yesterday it said the cheapest postage was $54. I'd be happy to pay even that if I was confident the gizmo would work. I'm not keen to get out the dremel and take a few mm off the braze on hanger so I guess I'll try the gizmo.

Cheers

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RonK
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Re: FD Problem junior gearing

Postby RonK » Wed Feb 14, 2018 9:57 am

rtnicho wrote:Thanks RonK. When I did the postage calculator thing yesterday it said the cheapest postage was $54. I'd be happy to pay even that if I was confident the gizmo would work.

It may depend on the destination, but I think you were looking at the Fedex rate, not the postage rate. I used the calculator and got $37.93 for Fedex and $17.90 for postage to Brisbane.

You may find the tail of the derailleur cage fouls the chainstay when mounted low. I would suggest for the small chain rings an IRD Alpina D derailleur.
Last edited by RonK on Wed Feb 14, 2018 11:30 am, edited 1 time in total.
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ironhanglider
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Re: FD Problem junior gearing

Postby ironhanglider » Wed Feb 14, 2018 10:43 am

rtnicho wrote:Thanks all

In response to ironhanglider one bike is currently running 46 x 16-27 (10 speed). With a 6 metre rollout 46 x 17 gives just under rollout so I block off 16 for non-state / national champs and use 2 17T cogs for other races. I suspect that this longer than expected rollout is because the tyres we use are 700x25 Conti GP 4000 SII which are quite a tall tyre, increasing roll out.

Cheers

Hi rtnicho,

Sorry for the bum steer with the 49T, I didn't realize the CA chart was using an odd wheel-size and didn't think to change it. A couple of mm of tyre makes a difference, but not that much.

Of course the simple option is 1x :D, then you can just choose a chainring to suit. Just tell the kid about rule 5 if the hills are too much! :twisted:

I might have to get into this space soon with my 8 year old son. At least for the moment the 5.5m limit is too big for him.

Cheers,

Cameron
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rtnicho
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Re: FD Problem junior gearing

Postby rtnicho » Wed Feb 14, 2018 11:49 am

Thanks again folks.
There's a good 2.5 cm of chain stay clearance @46T so fouling on that shouldn't be a problem.
So I bit the bullet and bought 2 WickWerks adapters, one for each bike. Came to about $AUS 100 delivered. Note the prices on the website are all $US.
I'll update the thread once I've fitted and had a play around with them.

rtnicho
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Location: Adelaide

Re: FD Problem junior gearing

Postby rtnicho » Mon Feb 26, 2018 6:05 pm

So, here's the promised update. The two adapters arrived and I tried fitting them to both bikes using 46T big chainrings. Wouldn't you know it the highest position I can get them to on both bikes is now too low and won't clear the outer chainring!! At least WickWerks will take them back. I checked out the IRD Alpina D FD in response to RonK's suggestion and IRD said it won't work with Shimano STIs. Short of buying two new frames for the kids I guess I'll have to try the CX-70 option and hope for the best. Is there such a thing as an outer chain catcher? I already use inner catchers. Maybe something from cyclocross? The chainsets are 6800 and 9000.

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