Cycling UK Forum

Hello everyone.
Once again I need to tap into your collective wisdom. I did a search of the forum but didn't find an answer. Apologies if I've missed a thread.

I have a new Stanforth bike and I am still in the process of tweaking the set-up. I am running (for the first time) 11speed GRX using a ZTT gear extender:
Rear changer RX800
Cassette XT 11-42
Chainset GRX 28/46
ZTT 25mm gear extender

When climbing fully loaded, long climbs such as the one from Malham over the moors to Settle, seemed even harder than on my previous bike running 9sp 24/36/48, 11-34. I changed the front chainring to 28 to help with this. I'm aware of course that age and fitness are playing a part in my travails! I haven't been on a fully-loaded ride yet, but cycling home through my local park (Meersbrook in Sheffield) with a shedload of shopping (12-15Kg?) was a relative dream. So far, so good. But when I first fitted the smaller ring I experienced some chain slip and realised that the chain was far too slack when using the 28/11 or 28/13. I fixed this by adjusting the B screw, even finding a slightly longer B screw by about 1.5mm. No chain-slip so far, and still able to cross chain. I'm not planning on using the extremes of the cassette with the inappropriate chainring, but realsitically I'm going to select them in error on occasion.

The extender link is cranked, vertical and 25mm centre to centre of the bolts. Is there a longer or better shaped alternative? Am I foolish to crank the chain tension up like that? (I have also slightly increased the clutch pressure}. The chain is the correct length with nearly but not quite enough to spare to remove a link. Will increased chain tension negate any advantage from the lower gear?
Thanks in advance for your thoughts,
Adrian

You're over the limit of the front mech for starters - extending the rear only helps it clear the bigger cassette cogs, not with the overall range it can deal with.

Put the original inner ring back on - I assume it came with the GRX standard of 31?
31:42 low gear is (to within a tiny margin) the same as 24:34 so the difference in climbing "feel" is far more likely to be down to bike position, weight etc than actual gearing.

The alternative is as you've found - you'll be stressing one or both ends of the spectrum.

I think you're on the limit of what you can expect from that derailleur with an extender. The RX800 RD has a nominal capacity of 39T. You are currently running with a capacity of 49T. The chain going a bit slack cross chained in little-little isn't a big problem, far better than a too short chain that rips off the rear derailleur in big-big. FWIW just avoid little-little (and if/when you forget at times it's not a disaster) and don't worry about it is my advice.

Thank you Rareposter. I'm having no problems with the front mech but will look out for it. The original ring was 30 so even close to the old bike.
Sound advice Cyclothesist. I'll slacken the b screw ever so slighly and not worry about it. Any problems over time and I'll go back to the original ring as rareposter suggested.

Cheers
Adrian

FWIW I too would first accept slack running in small-small gears as the lesser evil.

Brucey wrote: ↑19 Nov 2023, 12:32pm FWIW I too would first accept slack running in small-small gears as the lesser evil.

Thanks Brucey. I was hoping you’d reply! Very glad to see you back on the forum BTW.
Adrian

Deleted

cycle tramp wrote: ↑19 Nov 2023, 2:46pm

aflook wrote: ↑19 Nov 2023, 11:12am But when I first fitted the smaller ring I experienced some chain slip and realised that the chain was far too slack when using the 28/11 or 28/13.

Thanks in advance for your thoughts,
Adrian

Don't run the chain on the 28/11 or 28/13? In the same way as don't select 1st or 2nd gear when travelling at 70mph on a motorway.

When I had a triple - small ring for a long up middle ring for across or small ups, big ring for down or tail wind.

As I said above, I don’t intend to but inevitably might do so in error on occasion. I recall a Guardian motoring correspondent once changed into 2nd by accident at 100 mph and blew up £50,000 worth of Jaguar prototype. Details might not be exact. I don’t expect quite that catastrophic effect.

cycle tramp wrote: ↑19 Nov 2023, 2:46pm

aflook wrote: ↑19 Nov 2023, 11:12am But when I first fitted the smaller ring I experienced some chain slip and realised that the chain was far too slack when using the 28/11 or 28/13.

Thanks in advance for your thoughts,
Adrian

Don't run the chain on the 28/11 or 28/13? In the same way as don't select 1st or 2nd gear when travelling at 70mph on a motorway.

When I had a triple - small ring for a long up middle ring for across or small ups, big ring for down or tail wind.

As Rareposter said.

Or, in my experience the best way to get every gear you want including closer ratios than possible with an 11-42 cassette - the triple chainset you mention.

At present I have one ten speed bike left. It has (on one wheelset) a 14-36 cassette with a Shimano 52-39-30 triple chainset on the frame. The cassette goes: 14/15/16/17/19/21/24/27/30/36 and is shifted over with a 9-speed Shimano MTB gear changer of vast capacity and road 10-speed pull ratio.

Even 52/14 is a bit high for me these days; (I've got a spare 50 tooth ring, though). 30/36 is low enough still to get me up the odd black arrow hill, although the longer rascals might be a struggle nowadays (aged 74). But this bike is an 8 kilo racey summer thing, not a tourer.

I find close ratios needful these days, especially at the higher gear end. My most efficient power cadence range seems to be shrinking as I get older! Triple chainsets allow for this with a wide spread of gears but close ratios still possible.

The other thing about a triple chainset is that you never have to go near any cross chaining. But in practice, you can probably find a middle ring tooth count that will match your chosen cassette so that the middle ring is used most of the time. I can use all ten cogs of the cassette when in the middle ring, although I do avoid 39/14 (middle to highest gear cog) even though the chain doesn't rub the big ring in that gear.

Sadly, triple chainsets have been made "unfashionable" by the marketing gurus and faux racers so have become harder to buy - unless you've got a BSA thread BB, in which case head to Spa Cycles.

aflook wrote: ↑19 Nov 2023, 3:42pm I recall a Guardian motoring correspondent once changed into 2nd by accident at 100 mph and blew up £50,000 worth of Jaguar prototype. Details might not be exact. I don’t expect quite that catastrophic effect.

We have a ratchet freewheel so not much chance of having a gear problem by selecting the wrong gear.
Still don't understand the removing of a "granny ring" and then putting a dinner plate on the rear.
No criticism intended.

Cugel wrote: ↑19 Nov 2023, 4:12pm Sadly, triple chainsets have been made "unfashionable" by the marketing gurus and faux racers so have become harder to buy - unless you've got a BSA thread BB, in which case head to Spa Cycles.

If going to Spa Cycles then consider the super-compact double (40/24 or 42/26) and be prepared to pedal slightly faster if you run out of gears at the top end. I think of a double being high range + low range with some overlap whereas I didn't get on with a triple because of the extra complexity added by the middle gear range and more gearing overlap.

JohnR wrote: ↑19 Nov 2023, 9:37pm

Cugel wrote: ↑19 Nov 2023, 4:12pm Sadly, triple chainsets have been made "unfashionable" by the marketing gurus and faux racers so have become harder to buy - unless you've got a BSA thread BB, in which case head to Spa Cycles.

If going to Spa Cycles then consider the super-compact double (40/24 or 42/26) and be prepared to pedal slightly faster if you run out of gears at the top end. I think of a double being high range + low range with some overlap whereas I didn't get on with a triple because of the extra complexity added by the middle gear range and more gearing overlap.

The best mode of thinking about a triple chainset is not as a means to have an evenly spaced set of gears from top to bottom but rather three ranges of whatever gears you have at the back slower, medium and fast road speeds.

For example, on most of me West Welsh circuits I spend the first third of the ride going up, the middle third riding along an undulating ridge of the hills on one side of a valley and the last third generally going down again. Of course, one may find the route divided up into many more such sections of generally up, undulating or down than just those three thirds.

The little ring takes care of the longer and steeper upward sections of the ride; the middle ring is for being a rouleur (of sorts) on the undulating ridges and the big ring is for the long fast descents from up-a-height back down into the valleys.

Put another way, once you know a route, you select the ring with a usable range of gears for the next section of it that you're about to ride. It would be daft to try to change both ring and sprocket just to get the next closest ratio of the 30 or 33 gears.

Oh look, another thread where the bleedin' obvious answer is a triple.

Which are still available.

Instead there's loads of buggering about with massive rear sprockets, and god knows what widgets to get the rear derailleur to work.

Oh and look again. Somebody finds triples "complex".

I went straight from a Shimano Nexus hub gear, you know, straight up and down changes, to a triple derailleur set up. The first derailleur bike I've owned. I think it took me about half an hour to get the hang of the "complexity" of a triple set up.

Agreed but not an option when you have hydro brakes

maximus meridius wrote: ↑20 Nov 2023, 1:02am Oh look, another thread where the bleedin' obvious answer is a triple.

Which are still available.

Instead there's loads of buggering about with massive rear sprockets, and god knows what widgets to get the rear derailleur to work.

Oh and look again. Somebody finds triples "complex".

I went straight from a Shimano Nexus hub gear, you know, straight up and down changes, to a triple derailleur set up. The first derailleur bike I've owned. I think it took me about half an hour to get the hang of the "complexity" of a triple set up.

The question was not about the relative merits of different drive trains, but about optimizing the one I am using and I have received helpful comments on this from other people. I have ridden 9x3 drivetrains for many years and still do on my other bike. It just happens that the 11x2 seems to suit me and I enjoy the cycling more. We should celebrate the fact that cyclists are individuals with a range of tastes, experience, knowledge, riding purposes and quirks. Vive les differences!