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

velo.2010

You'll likely have to invest in a new chain too if your sticking on a bigger chainring. The 38 tooth chainset does appear small when compared to similar single ring gravel bikes - most range between 40 to 44 teeth. Do you do a lot of road cycling with the bike which would cause you to spin out in top gear?

magicbastarder

probably would be best to take a close up of the chainwheel and post it here, it's not quite clear what it is on the decathlon page.

AndrewJRenko

Type 17 wrote: »

It usually doesn't, but some lights (a few, older designs from the days of bottle dynamos) still rely on the negative side of the circuit returning through the frame and into the hub, so if your light doesn't work after re-wiring the plug, you should try reversing the polarity.

All sorted now, thanks for your help.

JerryHispano

Ok, some pictures now attached. Thanks for the tip about the new chain needed, that's not something I would have thought of. More expense :-(

I do more road cycling than otherwise, but even along gravel canal towpaths I was looking for a higher gear with none to be found.

I appreciate all the help thus far.

Type 17

CramCycle wrote: »

...BB does say 1.37 x 24T so I hope that means it is definitely English threaded...

Yes, 1.37(inches) x 24T(hreads per inch) is the English BB threading standard, so that means that the fixed cup (drive side) definitely unscrews clockwise.

velo.2010

JerryHispano wrote: »

I do more road cycling than otherwise, but even along gravel canal towpaths I was looking for a higher gear with none to be found.

Hmm. Many 'roadies' including myself are riding in the small ring at this time of year. My gearing is 36-13/36-14 at 90 RPM or so, on mostly flatish roads. If your managing that sort of cadence in your biggest gear (38-11) on a gravel bike then your going well!

However, I suspect your cadence is lower at about 60 RPM which is typical for beginners. If that's the case you should work on improving cadence in smaller gears and you won't need to replace the chainring.

TychoCaine

JerryHispano wrote: »

Ok, some pictures now attached. Thanks for the tip about the new chain needed, that's not something I would have thought of. More expense :-(

I do more road cycling than otherwise, but even along gravel canal towpaths I was looking for a higher gear with none to be found.

I appreciate all the help thus far.

That's a one-piece crank/chainring. You'll have to replace the entire thing. Square taper 1x cranksets are thin on the ground. Square taper is an old standard, but 1x cranks are the new sexy. There isn't much overlap apart from old skool track cranks used on fixies, but they're either mega expensive or Chinese made junk.

You'll find some stuff on eBay, but it's of questionable quality. If it was me, I'd swap out the bottom bracket for a modern external bearing BSA model, and you have a lot more options when looking at cranks.

And you will need a new chain also. They're cut to size when installed, and the current one won't be long enough to go on the large cassette cog without making your derailleur explode.

cletus

CramCycle wrote: »

Not yet but my lame excuse for a bench vice in my office can't do it and slips, so I ma off to a bigger vice in the workshop which is bolted to the table.

BB does say 1.37 x 24T so I hope that means it is definitely English threaded.

Colombus tubing but no sticker (has the nice detailing at the lugs).

Frame is light guessing SLX tubing by the weight.

You've a bench vice on the desk in your office??

Colour me very impressed. I've 4 bench vices, but I never thought to put any of them on my desk...

grogi

velo.2010 wrote: »

Hmm. Many 'roadies' including myself are riding in the small ring at this time of year. My gearing is 36-13/36-14 at 90 RPM or so, on mostly flatish roads. If your managing that sort of cadence in your biggest gear (38-11) on a gravel bike then your going well!

However, I suspect your cadence is lower at about 60 RPM which is typical for beginners. If that's the case you should work on improving cadence in smaller gears and you won't need to replace the chainring.

Cadence of 90 rpm with 38/11 and 27.5" wheel (typical for a gravel) is 42 km/h. Not something I could maintain for long on a flat, but certainly something I would see myself going over.

I myself am riding 46-30/34-11 on a gravel and often go above 100 rpms with the 46/11 gearing.

cletus

grogi wrote: »

Cadence of 90 rpm with 38/11 and 27.5" wheel (typical for a gravel) is 42 km/h. Not something I could maintain for long on a flat, but certainly something I would see myself going over.

I myself am riding 46-30/34-11 on a gravel and often go above 100 rpms with the 46/11 gearing.

[Pedantism]The bike has 700c wheels, so closer to 40km/h. Everything else stands[/Pedantism]

CramCycle

cletus wrote: »

You've a bench vice on the desk in your office??

Colour me very impressed. I've 4 bench vices, but I never thought to put any of them on my desk...

I do a lot of lab work so I try to build stuff for the lab in my office before I go in so I don't have to wear PPE , lab stuff is expensive but generally relatively easy to build or fix if you are in anyway handy. Also makes my office a workshop for bikes as well since my two office mates have been kicked out since covid stuff started.

JerryHispano

velo.2010 wrote: »

Hmm. Many 'roadies' including myself are riding in the small ring at this time of year. My gearing is 36-13/36-14 at 90 RPM or so, on mostly flatish roads. If your managing that sort of cadence in your biggest gear (38-11) on a gravel bike then your going well!

However, I suspect your cadence is lower at about 60 RPM which is typical for beginners. If that's the case you should work on improving cadence in smaller gears and you won't need to replace the chainring.

I've been tracking cycles on MapMyRide and I'd be in and around 36kph for a significant minority of the time (80 RPM going by calculators). So something I need to work on, but the gearing would be a problem regardless.

JerryHispano

TychoCaine wrote: »

You'll find some stuff on eBay, but it's of questionable quality. If it was me, I'd swap out the bottom bracket for a modern external bearing BSA model, and you have a lot more options when looking at cranks.

Have you any advice on what to go for or where to shop? BB standards seem to be the exact opposite of standardised.

Large bottle small glass

JerryHispano wrote: »

Have you any advice on what to go for or where to shop? BB standards seem to be the exact opposite of standardised.

Try Spa cycles. They have some square taper single chainsets.

Email to check regarding suitable bottom bracket to keep your chainline and that it's suitable for 10 speed

grogi

Large bottle small glass wrote: »

Try Spa cycles. They have some square taper single chainsets.

Email to check regarding suitable bottom bracket to keep your chainline and that it's suitable for 10 speed

When it comes to single speed chainrings, they are compatible with any speeds. Chainline will not be a big issue either, as there is no front derailleur reach. Sure, there might be a bit of chain flex, but nothing that cannot be fixed with different BB axle length.

Type 17

grogi wrote: »

When it comes to single speed chainrings, they are compatible with any speeds...

Careful here, as the link above shows a gravel bike with a 10-speed rear cassette, so the chain will be pretty narrow - you might get away with a 9-speed compatible chain ring, but 8-speed and lower (wider teeth) will probably cause the 10-speed chain to jam onto the teeth.

You should also measure the distance from the chainring to the seat tube and try to keep within 2-4mm of that distance, to avoid altering the chainline too much (assuming that Decathlon got it as good as possible in the design).

TychoCaine

Type 17 wrote: »

Careful here, as the link above shows a gravel bike with a 10-speed rear cassette, so the chain will be pretty narrow - you might get away with a 9-speed compatible chain ring, but 8-speed and lower (wider teeth) will probably cause the 10-speed chain to jam onto the teeth.

You should also measure the distance from the chainring to the seat tube and try to keep within 2-4mm of that distance, to avoid altering the chainline too much (assuming that Decathlon got it as good as possible in the design).

You can use any 1x chainring with any chain. The *inner* width of a chain (i.e. the roller width) is standard 2/32" regardless of the speed of the chain. The only thing different between an 8s and 10s+ chain is the *outer* width. Basically the side plates get thinner, leading to an overall thinner chain as you increase up from 8s.

Only 2x & 3x chainsets are speed specific, where the spacing between the 2 or 3 rings needs to match the width of a chain. There's a risk of a chain dropping between the chainrings if you use a 10s chain on a 2x8s chainset. if you use a 8s chain on a 2x10s chainset then you have the chain fouling on the inside surface of the big ring when it's on the small inside ring.

Type 17

Fair enough, I forgot about the inner dimensions being similar, especially when I was thinking of issues with 3/32" chain (8-speed) not working with ⅛" chainrings (single-speed) - those inner dimensions are very different.

TychoCaine

Type 17 wrote: »

Fair enough, I forgot about the inner dimensions being similar, especially when I was thinking of issues with 3/32" chain (8-speed) not working with ⅛" chainrings (single-speed) - those inner dimensions are very different.

Actually, Google is contradicting me. The link below says 5s - 8s has a roller width of 3/32", and 9s - 12s has a roller width of 11/128". How will I ever live down the shame of it!

https://bike.bikegremlin.com/1220/1-bicycle-chains-compatibility/

tdf7187

Sorry if this is a stupid question but after a rear derailleur and chain replacement, I noticed that my rear derailleur moves back and forward depending on the gear am I in. Is this normal or is the position supposed to be constant relative to the cassette?

Type 17

All fine, it swings back to take up the excess chain that results from using smaller sprockets/chainrings.

Here, let Calvin Jones tell you more.

[nerd mode] I love rear derailleurs - they're over 100 years old as a design, and many look almost organic (no straight lines). I brought a broken one to school back in the day, as a still life item and the art teacher liked it so much, he asked if I would donate it to the art class, which I did.[/nerd mode]

tdf7187

Great, thanks Type 17.

a148pro

a148pro wrote: »

Ok, problem on my bike and just wondering what went wrong

Got cranks replaced recently, and I think part of the bottom bracket. For some reason however the cranks are now jamming when I'm in the small ring. This seems to happen in the two easiest climbing gears. It doesn't happen all the time, I was a good hour or two into a cycle when it happened first. I can hear an occasional sound similar to the sound when a chain comes off but everything is otherwise spinning perfectly. While looking down to see what was going on I could see that the RD was popping forward a bit every so often, like bobbling towards the front of the bike a couple of inches. Then every so often the cranks totally jam. I'm not sure what happens below at this point, I think the RD goes fully forward, but it feels like the feeling when you're about to break your RD by forcing it through (if that makes any sense). It doesn't seem to be catching a spoke.

None of this happened before the cranks were replaced. Wondering if the bike shop made a balls of it or could the derailleur have hit something while I put it in a car recently?

It doesn't happen in the big ring at all, the only thing that happens there is in the easiest climbing gears there's a kind of rattle from the chain, this was here before.

Any ideas, its probably something very simple I'm just useless when it comes to maintenance

So I couldn't recreate this for the LBS but the chain was a little dry and unlubed, so I lubed it and did 60k without incident the other day

Could this have just been caused by the chain being too dry?

a148pro

And while I have you, I used a kind of strap thing to fix a pump to my crossbar recently, but unbeknownst to me it was rubbing. There are now these kind of dry dusty scratches on the frame that go away when you wet them but come back thereafter, but more importantly, there's a kind of "scab" through the paintwork where the pump was rubbing the down tube.

I think I've seen little circular patches you can buy to protect these further, can anyone recommend? Google isn't being very helpful

Very annoying that for want of a pump mount this happened

CramCycle

a148pro wrote: »

So I couldn't recreate this for the LBS but the chain was a little dry and unlubed, so I lubed it and did 60k without incident the other day

Could this have just been caused by the chain being too dry?

The only time I have had similar was when the chain might jam in the rear derailleur on one of the jockey wheels. If the chain was gunked up or stiff it would happen far easier. It could be a sign that the chain is slightly too long, but more likely the jockey wheels/chain are worn/dirty, or the actual part that holds the jockey wheels is slightly out of line. Long story short, if this was your issue, a clean and a lube would sort it out for the most part.

cletus

a148pro wrote: »

So I couldn't recreate this for the LBS but the chain was a little dry and unlubed, so I lubed it and did 60k without incident the other day

Could this have just been caused by the chain being too dry?

It might, but it can be hard to say. Just keep an eye on it

Here's a link to frame protection patches

https://www.chainreactioncycles.com/mobile/ie/en/lifeline-frame-protection-patch-kit/rp-prod150265?gs=1&sku=sku547859&istCompanyId=0f15660a-f13e-4c09-a701-b55d8c3f2e59&istFeedId=21ccdaa5-24f7-4b32-9ec6-ac7081b9b50b&istItemId=iwxrpplpt&istBid=t&pgrid=55940684581&ptaid=pla-414380983900&utm_source=google&utm_term=&utm_campaign=PLA+All+Products&utm_medium=base&utm_content=mkwid|s7kyjyVQ4_dm|pcrid|294740729975|pkw||pmt||prd|547859IE&gclid=CjwKCAiA_Kz-BRAJEiwAhJNY7-dFZcIzQbZTgOfqrbnOJFlTNkA1ma0I36UEuOqmEDlQWzS4TRN1nhoCB_IQAvD_BwE

a148pro

cletus wrote: »

It might, but it can be hard to say. Just keep an eye on it

Here's a link to frame protection patches

I think I'm looking for something slightly different - a patch to go over a damaged bit of frame, i.e., not see through, black probably or matched to the frame colour

CramCycle

a148pro wrote: »

I think I'm looking for something slightly different - a patch to go over a damaged bit of frame, i.e., not see through, black probably or matched to the frame colour

What is the frame material? If its steel, a light buff and some nail polish of the right colour. Aluminium, straight on with the nail polish (or simply leave it if you don't mind the aesthetics.

CormacH94

I know this question has been done to death but - new bike or upgrade components?

Looking at upgrading a Tiagra Alloy Frame to Ultegra & New Wheels. Did some number crunching and allowing 800 for mechanical Ultegra and 500 for wheels/tires that's 1300, I'd be doing the work myself so no shop costs.

Am I mad to be spending that over a whole new bike? I know I could probably get Ultegra and Carbon frame for 2k but I'm not sold on carbon as I'm a bit rough and ready with my bikes and don't have very clean/safe storage (i.e, my bikes tend to get a bit knocked around) and it would I think it would kill me to be treating a carbon bike like a piece of glass.

I've looked at the CAAD13 and Allez Sprint but I'm a bit fussy over components such as wheel and tires and don't like the idea of buying a build with no choice of wheels/tires etc.

Should I go ahead with the upgrades and maybe in a few years look at getting a carbon frame and moving parts over?

magicbastarder

what's the frame? might be overspeccing the components on an average frame.
also, why not just consider going secondhand? you'd get a nice bike S/H for that price.

(and if you're doing this on the BTW scheme, just pretend otherwise!)