turbofurball Posted December 16, 2016 Report Share Posted December 16, 2016 Today I finally got around to properly cleaning up my chain and sprockets (half an hour with the parts washer, should have done it sooner!) and I noticed my front sprocket has noticeable wear, while the chain and back sprocket look fine ... if this was a road bike I'd be ordering a new set, but since this is a little 125 with a chain tensioner as I ok to carry on for a good while yet? Do you replace the lot, or just whats worn? This is my first trials bike, so I'm still learning the finer points of it's maintenance! Quote Link to comment Share on other sites More sharing options...
lineaway Posted December 17, 2016 Report Share Posted December 17, 2016 Does the front sprocket have worn or bent teeth? Or is it nice and shiny from metal on metal? The rear is usually aluminum, so does not shine like the front. I go through 2-3 chains to a set of sprockets. Crazy some say, but trials is different from all motor sports. We do not put thousands of miles on a set of sprockets, we put hundreds. Our wear comes from all the starts and stops and stress of ups and drops. We ride in dirt, mud and water. Slowly, and then zap a big rock. Which stretches said chain. Do you know Montesa recommends the 4rt piston to be replaced after like 60 hours? Most 4RT riders are still on the stock piston ten years later. Say it isn`t so! Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted December 17, 2016 Report Share Posted December 17, 2016 I don't know about your bike but some front sprockets can be turned round occasionally to even out the wear. Back when I was doing a lot more riding than now I ran two chains and swapped them every couple of trials which helped extend chain and sprocket life. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted December 17, 2016 Report Share Posted December 17, 2016 It depends on how much you use your bike, in which terrain and weather conditions you have ridden. Even which chain you use. In my experience MX chains do last extremely well and worth their money DID ERT2. I replace the chain when the chain has got signs of wear being to long or having too much side play or if the chain has been damaged partly by a rock for example. When I change the chain I change both sprockets too. Worn sprockets will ruin new chains as worn chains can will ruin new sprockets, this is mandatory. I have some bikes. I get several seasons with one chain and sprocket set up when using MX chains. With standard light Regina chains less. Quote Link to comment Share on other sites More sharing options...
trapezeartist Posted December 17, 2016 Report Share Posted December 17, 2016 Obviously the "perfect" answer is to change sprockets and chain at the same time. The pragmatic answer is less clear. Using a worn chain means that the effective pitch has increased, so instead of distributing the load all around the sprockets all the load will fall on one or two teeth at the top. That is going to accelerate wear on the sprockets. Using a worn sprocket will eventually cause the chain to jump a tooth under load. (My first trials bike bought in 1969 did that when I first got it.) But generally you will change it before it gets that bad. Using a hooked sprocket will wear the chain and make it snatchy. My own conclusion would be that you should change the chain when it's stretch measures outside the acknowledged limits (which I've forgotten!). No need to change the sprockets as long as they look good. Change a sprocket if you can see the wear or hooking. Quote Link to comment Share on other sites More sharing options...
guys Posted December 17, 2016 Report Share Posted December 17, 2016 (edited) A picture of your worn front sprocket would be helpful. I also use 2 chains ( is a more common practice on mountain bikes) so the sprockets last longer. Most chain wear on trials bikes comes from dirt and/or lack of lubrication. A 520 chain can take much more power than our trial bikes can produce. (top riders with their high peak loads excluded maybe) I replace everything when I can almost see a complete tooth, when I pull on the chain at the rear of the rear sprocket. I don't want to run the risk of a broken chain punching a hole in my engine casing. ( fwiw: a worn chain isn't stretched, it means that the pivot pins and bushings are worn, and worn pins break easier) If possible use a 10T front sprocket. Chains don't like to take sharp bends and it reduces wear a little bit. Edited December 17, 2016 by guys 1 Quote Link to comment Share on other sites More sharing options...
trapezeartist Posted December 17, 2016 Report Share Posted December 17, 2016 If possible use a 10T front sprocket. Chains don't like to take sharp bends and it reduces wear a little bit. I'll second that. When I started karting we were running narrow 3/8 pitch chain on a 9T sprocket spinning at 15000 rpm. Chains lasted about one and a half hours, if you were lucky. 1 Quote Link to comment Share on other sites More sharing options...
zippy Posted December 17, 2016 Report Share Posted December 17, 2016 I think this would be a good time to change sprockets. Might just go all nuts and do the chain as well. 1 Quote Link to comment Share on other sites More sharing options...
zippy Posted December 17, 2016 Report Share Posted December 17, 2016 I am not sure if I just don't ride as often as everybody else, but I get 2 seasons out of a set of chain and sprockets. When I run out of adjustment on the snail cams I get new chain and sprockets. (This is not to endorse any supplier but to show what I personally use) Most of the time I get the chain and sprocket package deal from Tryalsshop. it has gone up in price by $10 in the past few years, but still a good deal http://www.tryalsshop.com/#!/Chain-&-Sprocket-Package/p/358896/category=162476 1 Quote Link to comment Share on other sites More sharing options...
lineaway Posted December 17, 2016 Report Share Posted December 17, 2016 I`ve seen bikes come in for a new clutch with counter shaft sprockets that resemble that pic. Quote Link to comment Share on other sites More sharing options...
cleanorbust Posted December 17, 2016 Report Share Posted December 17, 2016 "I think this would be a good time to change sprockets. Might just go all nuts and do the chain as well." You could at least leave it till the points have rounded off a bit. 1 Quote Link to comment Share on other sites More sharing options...
axulsuv Posted December 17, 2016 Report Share Posted December 17, 2016 I think this would be a good time to change sprockets. Might just go all nuts and do the chain as well. Why Change a Trick Downhill Sprocket ??? 1 Quote Link to comment Share on other sites More sharing options...
turbofurball Posted December 17, 2016 Author Report Share Posted December 17, 2016 Ha! Thanks guys ... I can't take a photo right now as my bikes parked up at work, suffice it to say that the leading edge is noticeably worn down to the tune of about 1 to 1.5mm, while at the back the tooth shape appears nearly perfect. The front one also has a little play on the shaft, and the more I think about that the more it worries me! Since I'm a newbie and about to turn 40 I'm not doing any extreme riding, so for now I'll just get a cheapo new front and be prepared to put a whole new set on in the spring ... possibly with a lower ratio, since it's 10/42 at the moment and I'm just doing everything in first (it started out as a 250, and got demoted to a 125 after the previous owner killed the piston and barrel). Quote Link to comment Share on other sites More sharing options...
ruffmutt Posted December 17, 2016 Report Share Posted December 17, 2016 Gearbox sprockets wear more because of the much smaller radius, i,e, less teeth. If the the chain fits the rear sprocket o k, assuming the teeth on the sprocket are o k, just renew the sprocket on the gearbox. Don,t tell the dealer what I said, he wants to sell you the lot! 1 Quote Link to comment Share on other sites More sharing options...
turbofurball Posted December 19, 2016 Author Report Share Posted December 19, 2016 10/42 does that involve a lot of clutch slipping to keep it on the boil.or do you weigh 40 kg Lots of clutch slipping, in fact so far I've not managed to find a use for 2nd gear in a section ... judging by this reply I should definitely remedy this! Quote Link to comment Share on other sites More sharing options...
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