the 'there's no such thing as a stupid question' bike maintenance thread

breadevery · 08-09-2022 10:42am

Hi everyone,

I picked up a direct drive trainer a little while ago. When I use it, it is messing up my front derailleur shifting, both on the trainer and afterwards. It doesn't happen immediately but after a couple of hours of use, the shift to the big chainring becomes poor, and eventually stops shifting altogether.

The cassette on the trainer is a Shimano 11-speed, like my bike, but it's an 11-28 (bike has an 11-36). I don't think the different sizes should cause the issue, but could it be that? Or could it be something to do with spacers on the trainer cassette? Maybe it needs a spacer behind the biggest cog? All suggestions welcome, cos I'm flummoxed!

hesker · 08-09-2022 11:38am

I don’t have a trainer but are you sure you don’t also have shifting issues on the road. These can be intermittent until cable breaks. Assuming mechanical of course.

I’d check the cable at the shifter end to see if it’s fraying

breadevery · 08-09-2022 12:42pm

Thanks, but no it's not that. The bike is only a few months old and shifts perfectly on the road until I put it on the trainer.

cletus · 08-09-2022 12:49pm

When you put it back on the road, does it return to shifting normal?

To be honest, it doesn't make a lot of sense. The pull ratio is set, so it should not be affected by the turbo.

My immediate thoughts would be the cable. New cables often have a little stretch in them, and need adjusting after the first few weeks of use. That would be my first port of call

hesker · 08-09-2022 1:13pm

Your front der operates independently of the rear so whatever it is it’s nothing to do with the trainer. Nothing that I can imagine anyway.

Possibilities

Frayed cable
Cable loose and slipping where it is bolted down at front der
Ratchet components worn/not engaging in shifter
Something loose like a towel hanging down and trapping the front der when you’re on the trainer

Maybe get someone to have a look at it for you. It should be easy to sort out

breadevery · 08-09-2022 1:38pm

When I go back on the road the shifting is still off. I've been to the LBS twice to readjust it, and get it back shifting correctly, but each time I put it on the trainer, the same thing happens again. It's almost as though the FD is being pulled inward when mounted on the trainer. It's a GRX 810 FD, so I think it sits 2.5mm further out from the frame than other Shimano FDs,could that have anything to do with it?

breadevery · 08-09-2022 1:40pm

I should add, I hadn't put it on the trainer for 2 weeks before yesterday. Shifting had been perfect, and I'd done about 15 hours on the bike. after 1 hour on the trainer, it wasn't making the jump to the big chainring.

Elvis Hammond · 08-09-2022 1:51pm

https://www.boards.ie/discussion/comment/119589519#Comment_119589519

If the FD is being pulled by the chain, you'd expect a bit of noise.

Could frame flex be an issue; maybe you're putting a lot of pressure all on one side? What's the frame material?

breadevery · 08-09-2022 1:55pm

I do notice noise from the chain that I wouldn't normally hear outside, that's what made me suspect the cassette position might be off and it was pulling the chain inwards, but I don't even know if that's possible! It's a carbon fibre gravel bike, quite flexy, so maybe that's something to do with it?

CramCycle · 08-09-2022 2:01pm

I suspect your FD just isn't set right, you get away with it outside as you can't hear the chain rub and like many FD issues with not being set right, if you are moving the rear mech at the same time, it can help it move up, even though they are not related. Put the FD on the inner ring and see is there any slight slack on the cable. When it is in the big ring is it where it should be exactly? I imagine, loosening the cable when its in the inner ring, pulling the cable tight while pushing the FD outboard a bit and then tightening the bolt again (hard to do if you have not practised, a third hand makes it easier).

breadevery · 08-09-2022 2:17pm

Thanks! There is quite a lot of slack in the cable on the smaller chainring. I currently only have 1 hand, as Im carrying my toddler with the other one, but I'll try your fix later when i can recruit a helping hand and report back!

hesker · 08-09-2022 3:19pm

If your LBS can’t set an FD properly you need a new LBS.

Agree FD might need adjustment but impact should be same on road or trainer

CramCycle · 08-09-2022 7:22pm

https://www.boards.ie/discussion/comment/119589851#Comment_119589851

If its slack then there is your issue, might not even need to push it outboard, just pull it with a pliers in one hand and then tighten the bolt with the other.

breadevery · 08-09-2022 7:30pm

I've tightened the cable as suggested, and it's back shifting beautifully on the road. I'll stick it on the trainer tomorrow for the big test!

nicksnikita · 08-09-2022 8:11pm

https://www.boards.ie/discussion/comment/119591795#Comment_119591795

I had the same fd issue a few years back (just on road) and it turned out to be a dodgy cable tension adjuster barrel.

I would set up the fd, add tension using the barrel, then the barrel would lose tension gradually until the fd wouldn’t shift..

May be something to check if your bike has this type of tension adjuster

DeadSkin · 09-09-2022 12:11pm

Hi folks - I ordered some disc pads and when I pulled out the ones I want to replace they are slightly larger than the new ones I got - see picture.

Dsic Pads.jpg

I popped in the new ones and they seem to fit as well as the originals, and took the bike for a quick spin, all seems fine. Should I be concerned, any chance they could fail because of the difference in size?

Thanks.

CramCycle · 09-09-2022 4:10pm

https://www.boards.ie/discussion/comment/119594856#Comment_119594856

Can you put up the brake model and the code of the ones you ordered, it should be fine but just in case. I've filed down ones that are two big with out issue but thats the reverse of your issue (wouldn't do it again, alot of effort). For you I imagine it is a case of if it is possible to get leteral movement.

DeadSkin · 10-09-2022 10:35am

https://www.boards.ie/discussion/comment/119596076#Comment_119596076

Brakes are Shimano, nothing to indicate what model though..

The pads I removed are Shimano and have SD4QJ stamped on them.

Pretty sure these are the ones I bought https://www.decathlon.ie/kids-bike-brake-pads/310553-13084-shimano-compatible-road-bike-disc-brake-pads.html

Just as I paste the link I see kids brakes in the address!!!?

Just checked the invoice from Decathlon and the description is Shimano Compatible Road Bike Disc Brake

Pads - Color : PURPLE- Size : No Size

Thanks.

secman · 10-09-2022 11:00pm

Trying to source a top and bottom pair of headset bearings for a 2017 Trek emonda. A guy on spin today said to try Reliance Bearing Co in ballymount . Reckons you can get any bearings you need for any bike headset or bottom bracket there ?

Anyone on here use them ?

cletus · 11-09-2022 7:34am

https://www.boards.ie/discussion/comment/119601624#Comment_119601624

Never used them, but they seem to be a parts supplier for industry that have a range of bike bearings. The bearings on their website aren't listed by bike or anything, so it seems like all you'd need to order is the bearing dimensions.

https://reliance.ie/search?q=bicycle&count=29

secman · 11-09-2022 11:40am

Unfortunately Reliance don't have anything matching the dimensions I need. The search continues,,, will try Gary's in Sligo on Tuesday.

cletus · 11-09-2022 1:21pm

https://www.boards.ie/discussion/comment/119602667#Comment_119602667

What size do you need, out of curiosity

secman · 11-09-2022 1:54pm

51 40 7 and 41 30 7

I think the 7's are more likely to be 6.5 mm

07Lapierre · 11-09-2022 7:56pm

Try Dickson bearings in finglas

DeadSkin · 12-09-2022 8:48am

https://www.boards.ie/discussion/comment/119596076#Comment_119596076

If it helps, I've attached a picture of the original disc pad - thanks.

Old-Disc-Pad.jpg

Mundo7976 · 14-09-2022 10:12am

Hi all.

Bike currently has 11/32 cassette. Am considering replacing with 11/28.

Is there any benefits to this apart from having to work harder on hills?

Also, would I need to shorten the chain or have to change derailleur?

magicbastarder · 14-09-2022 10:31am

one of the benefits would be that your gears will be more closely spaced, so easier to get one that suits the particular rhythm you want.

you would generally shorten the chain in this situation.

Mundo7976 · 14-09-2022 10:41am

Thanks for that. Just edited, it's a 32.

Would it be safe to test on a decent ride with the original chain length without prematurely removing links?

magicbastarder · 14-09-2022 10:56am

the danger would be putting a bigger cassette on without lengthening the chain - but putting a smaller cassette on (which is what you're doing) would not be a huge issue, as i understand it.

Klopp · 14-09-2022 11:16am

Can someone recommend a grease I can use for pedals, handlebars etc. for a road bike when assemblying?

the 'there's no such thing as a stupid question' bike maintenance thread

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