spinningplates Posted November 4, 2012 Report Share Posted November 4, 2012 Just about to replace sprockets. what would be the best sprocket sizes front and back for genral trials sections. Many thanks. Quote Link to comment Share on other sites More sharing options...
woody Posted November 4, 2012 Report Share Posted November 4, 2012 Rear sprockets come in two sizes, 46 which was fitted to MK1 and 42 which was fitted to MK2 onwards. MK1 MAR is listed as having 46 / 12 but I'm pretty sure that would be quite high. I've never used a 12 tooth front sprocket. I always used to run 42 / 10 on my MK2 as I prefer low gearing using the smaller rear sprocket but you can have problems with the chain riding over the boss on a 10 tooth sprocket, so 11 is better. 42 / 11 gives higher but perfectly useable gearing in sections and you can use bottom for virtually everything with that. 46 / 11 is not far off the 42 / 10 combination for a lower option. If you don't mind the bigger of the rear sprockets, you could go for 46 / 11 as a lower option. Ultimately it's personal choice, but either of 42 / 11 or 46 / 11 will work ok. 1 Quote Link to comment Share on other sites More sharing options...
spinningplates Posted November 5, 2012 Author Report Share Posted November 5, 2012 Thank you Woody very comprensive answer. Its a mk1 so have gone for 46 / 11. fingers crossed should be the last thing I put on the the bike which was meant to be a cheap rebuilt renovation project. What was I thinking ? Quote Link to comment Share on other sites More sharing options...
woody Posted November 5, 2012 Report Share Posted November 5, 2012 fingers crossed should be the last thing I put on the the bike which was meant to be a cheap rebuilt renovation project. What was I thinking ? HaHa - I know what you mean - if ever you find the secret to one of those, let me know... Quote Link to comment Share on other sites More sharing options...
Old Posted yesterday at 05:58 PM Report Share Posted yesterday at 05:58 PM Hi, this is really helpful. I want to reduce the gearing on my '72 MAR, and the 10T front seems like a good idea, but I wasn't sure what "chain riding over the boss" meant. Is there something that the smaller radius causes it to hit in the case under limits of suspension travel? Also, good sources for sprockets would be useful. I'm new to this... Quote Link to comment Share on other sites More sharing options...
woody Posted 23 hours ago Report Share Posted 23 hours ago The retaining nut is almost as big as a 10 tooth sprocket which means the chain rides up over the points of the nut when it is flush against the sprocket. To use a 10 tooth there is a nut with a shoulder on the inside to give clearance to the chain, you need to use this nut Depends where you live, in the UK, In Motion have all you need I run a dished rear sprocket on my MAR which only comes in 44 tooth size, this works well with the 10 tooth front Quote Link to comment Share on other sites More sharing options...
Old Posted 19 hours ago Report Share Posted 19 hours ago Thanks, Woody. I'm in the US, so I'll have to see if In Motion can ship to me. I will search for a US source as well. We have a rather "fluid" tariff situation and now the "de minimus" exemption has been rescinded which means small shipments (like a sprocket and a nut) go through the same process as a cargo container of goods. If worse comes to worse, I can machine a special nut as I'm fortunate to have a nice machine shop. Finding a sprocket will still be a challenge as I have not had experience with machining internal splines... may have to learn. Again appreciate your knowledge and generosity to share it. Quote Link to comment Share on other sites More sharing options...
woody Posted 2 hours ago Report Share Posted 2 hours ago In the US you have Hogans, Alex Snoop, Keith Lynas, Vintco Quote Link to comment Share on other sites More sharing options...
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