331sam331 Posted October 12, 2014 Report Share Posted October 12, 2014 Firstly, hello. New to the forums although been lurking for a bit. Went to my first trials event a couple of weeks ago and got the bug. Went out this weekend and bought a nice 315r. Anyway, it is road registered and after a bit of tlc (wheel bearings, brakes and bushes) I would like to do the odd commute on it between trials when it is dry and preferably sunny... My route to work is mainly country lanes and one single 60mph A road that lasts about 2 miles. Planning on getting the long range seat but I think I should be alright on fuel. So does anyone here have experience riding a modern(ish) trials bike on the road for a few miles? Would I need to change the fuel ratio? Also what sprocket combination would be suitable for longer gears? Thanks! Quote Link to comment Share on other sites More sharing options...
cascao Posted October 13, 2014 Report Share Posted October 13, 2014 2 miles only? Just don't hold it wide open. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted October 13, 2014 Report Share Posted October 13, 2014 To make a useful difference to gearing for road use would need a change of 25 to 30%. This would probably ruin it for trials. If thebike feels low geared for trials go up 1 tooth on the gearbox and / or down 3 or 4 on the rear wheel. Fit a handlebar lever to operate your cold start enrichment so you can give it a bit of extra fuel to oil and cool the engine, especially on the overrun or high throttle. Quote Link to comment Share on other sites More sharing options...
jrsunt Posted October 13, 2014 Report Share Posted October 13, 2014 When running the 315 in the ssdt, we would put a 38 rear sprocket on, still ok for the sections but sat more comfortably on the roads. The std 41 should be ok if you don't cane it everywhere Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 13, 2014 Author Report Share Posted October 13, 2014 2 miles only? Just don't hold it wide open. Yea, probably less than that actually. It is also a well know cycle route so I don't have to do 60mph. I would get away with between 40-50mph most likely. I am not really sure 60mph on a trials bike will be too comfortable. Probably pretty exciting though haha... Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 13, 2014 Author Report Share Posted October 13, 2014 To make a useful difference to gearing for road use would need a change of 25 to 30%. This would probably ruin it for trials. If thebike feels low geared for trials go up 1 tooth on the gearbox and / or down 3 or 4 on the rear wheel. Fit a handlebar lever to operate your cold start enrichment so you can give it a bit of extra fuel to oil and cool the engine, especially on the overrun or high throttle. How about if I had a spare set of sprockets I could change over? Bearing in mind I plan to commute pretty rarely. Would I also have to change the chain with such a difference in sprocket sizes? Would I be OK running different jets and say a 50:1 fuel mix? (standard is 80:1). Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 13, 2014 Author Report Share Posted October 13, 2014 When running the 315 in the ssdt, we would put a 38 rear sprocket on, still ok for the sections but sat more comfortably on the roads. The std 41 should be ok if you don't cane it everywhere Sounds good, I'll have to play around with some different set ups. Cheers for the suggestion. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted October 13, 2014 Report Share Posted October 13, 2014 Going up one tooth on gearbox will give near same effect as JR Sunts suggestion of going down 3 on the rear. Going up on gearbox sprocket will also make bike run smoother. I am not familiar with your bike, if there is room and a bit of slack in the chain you may be able to go up 2t on gearbox which would be a lot easier than changing chain and rear sprocket as well. My preference is for much richer oil mixtures than 80:1. I don't know how much riding you have done but with a bit of experience you can tell when your bike is getting a bit hot, usually power starts to fall off and it may start pinking. Handlebar control of cold start enrichment is easy, cheap way of countering this. Quote Link to comment Share on other sites More sharing options...
michael_t Posted October 13, 2014 Report Share Posted October 13, 2014 At 60 mph for 2 miles you are only talking 2 minutes you could most likely hold it wide open but would be more concerned about your safety than the bike. My Sherco X-Ride has a 290 trials motor and transmission when I am riding on the road I try to vary the throttle and not just hold it in one position for prolonged periods of time I will also pull in the clutch and just let it idle every now and then. I do run it at 50:1 as per the manual and I am thinking of going to 40:1. I like to idea of rigging up a cold start lever on the bars but wouldn't bother for a 2 minute burn down the road every now and then. Be sure the bike is warmed up before hitting the road wide open. Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 14, 2014 Author Report Share Posted October 14, 2014 Going up one tooth on gearbox will give near same effect as JR Sunts suggestion of going down 3 on the rear. Going up on gearbox sprocket will also make bike run smoother. I am not familiar with your bike, if there is room and a bit of slack in the chain you may be able to go up 2t on gearbox which would be a lot easier than changing chain and rear sprocket as well. My preference is for much richer oil mixtures than 80:1. I don't know how much riding you have done but with a bit of experience you can tell when your bike is getting a bit hot, usually power starts to fall off and it may start pinking. Handlebar control of cold start enrichment is easy, cheap way of countering this. Right OK. I think I will go for that option as I don't want to fork out a load of money on sprockets/chains. So when you say smoother, do you mean less snappy when pulling off? (total novice here...) Cheers for the reply. At 60 mph for 2 miles you are only talking 2 minutes you could most likely hold it wide open but would be more concerned about your safety than the bike. My Sherco X-Ride has a 290 trials motor and transmission when I am riding on the road I try to vary the throttle and not just hold it in one position for prolonged periods of time I will also pull in the clutch and just let it idle every now and then. I do run it at 50:1 as per the manual and I am thinking of going to 40:1. I like to idea of rigging up a cold start lever on the bars but wouldn't bother for a 2 minute burn down the road every now and then. Be sure the bike is warmed up before hitting the road wide open. What would be dangerous about it? Thanks for the reply. try to wheelie the whole way Don't tempt me! Does anyone know what kind of tyre pressure would be best for the road? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted October 14, 2014 Report Share Posted October 14, 2014 (edited) The smoother running with more teeth on gearbox sprocket is nothing to do with pulling away. As the sprocket rotates the actual diameter of the point at which it contacts the chain varies, the more teeth the sprocket has the less this variation is and hence less vibration. Imagine the vibration you would get with square wheels with 4 large flats compared to a round heel which has an infinitely large number of infinitely small flats. This is why smaller road bikes run 428 chains, there are more teeth for a given diameter. The handlebar operated enrichment is a common mod for beach / sand racing, particularly important for slowing down from high speed with throttle closed (no oil getting to engine) or when running at high speed with partial throttle which tends to cause weak running with insufficient oil. When defending long hills on a trials, enduro or mx bike you should periodically blip the throttle to give the engine a bit of oil. should say descending not defending Edited October 15, 2014 by dadof2 Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 14, 2014 Author Report Share Posted October 14, 2014 The smoother running with more teeth on gearbox sprocket is nothing to do with pulling away. As the sprocket rotates the actual diameter of the point at which it contacts the chain varies, the more teeth the sprocket has the less this variation is and hence less vibration. Imagine the vibration you would get with square wheels with 4 large flats compared to a round heel which has an infinitely large number of infinitely small flats. This is why smaller road bikes run 428 chains, there are more teeth for a given diameter. The handlebar operated enrichment is a common mod for beach / sand racing, particularly important for slowing down from high speed with throttle closed (no oil getting to engine) or when running at high speed with partial throttle which tends to cause weak running with insufficient oil. When defending long hills on a trials, enduro or mx bike you should periodically blip the throttle to give the engine a bit of oil. I see what you mean now yea. That square wheels explanation was bang on. Thanks for the tips! Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted October 15, 2014 Report Share Posted October 15, 2014 For road running, I would suggest at least 12 - 15 PSI air pressure. Remember that trials tires are a soft compound and will wear quite quickly on pavement. I don't know where you are located but in the USA, tires to be legally used on public roads must be DOT approved. The very things that make a trials bike good for trials, make them not so good for road riding. The frame and suspension geometry of a trials bike will make the bike quite twitchy at higher speeds. Quote Link to comment Share on other sites More sharing options...
michael_t Posted October 15, 2014 Report Share Posted October 15, 2014 Pirelli MT43 is a DOT tire that should hold up a bit better on the road. They sell it as a "competition tire" but it is no Michelin . Quote Link to comment Share on other sites More sharing options...
331sam331 Posted October 20, 2014 Author Report Share Posted October 20, 2014 For road running, I would suggest at least 12 - 15 PSI air pressure. Remember that trials tires are a soft compound and will wear quite quickly on pavement. I don't know where you are located but in the USA, tires to be legally used on public roads must be DOT approved. The very things that make a trials bike good for trials, make them not so good for road riding. The frame and suspension geometry of a trials bike will make the bike quite twitchy at higher speeds. Alright great. Yea I notice how soft they are just from touching them compared to say a car tyre. Ah, I see. Well I guess I'll just have to take it easy and find a speed that is comfortable, cars can always go round me haha. Pirelli MT43 is a DOT tire that should hold up a bit better on the road. They sell it as a "competition tire" but it is no Michelin . The front is Michelin and the rear is an IRC tyre. Both are fairly new with the mould marks still there. Thanks for the suggestion Thanks to everyone for there help, really appreciate it Quote Link to comment Share on other sites More sharing options...
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