I am going to fit a new chain and sprocket . I haven't had my TDM 900 long but I did do a lot of miles over weekend and got the feeling that the bike would benefit from a change in the gearing so that it does more revs per mph . This would help particularly in town riding when I seem to be in first most of the time and second would be better and also keep the revs out of the 3.5k to 4k zone more of the time. I understand that standard gearing is 16 front and 42 rear . I am thinking of going 15 front . Has anyone else done this with positive results ?
I dropped one tooth on the KLE when I had it and it made a world of difference particularly commuting around town. I'm thinking of doing the same when I change the chain and sprockets on my 900. The extra revs are no real disadvantage at highway speeds either.Â
Check out this:Â https://www.gearingcommander.com/Â ... so that you don't make a mistake when choosing sprockets (espeically at the bottom of page - chain wear)
Mine's non-abs so any gearing change is going to affect the speedo reading. I'm guessing that standard speedo error is that it reads fast and if my thinking is correct then dropping a tooth on the front sprocket will make the speedo read even faster . I suppose this might affect my insurance if I have an accident but I would also want to know how fast I am going so for these reasons I am going to stick to standard gearing.
Quote:Mine's non-abs so any gearing change is going to affect the speedo reading. I'm guessing that standard speedo error is that it reads fast and if my thinking is correct then dropping a tooth on the front sprocket will make the speedo read even faster . I suppose this might affect my insurance if I have an accident but I would also want to know how fast I am going so for these reasons I am going to stick to standard gearing.
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I don't think it would affect insurance unless it over reads by more than the 10% the construction and use regulations allows for those earlier years. They've tightened up on it with later vehicles but I don't know the year off the top of my head. The regs state that a speedo must never under read. Also, the speedo is not an MOT item !
Hi - reading through this thread, as sometime in future I am thinking of a 15 tooth front sprocket. A friend reckons it will make the 900 more useable. A couple of questions - someone said the speedo error wouldn't affect the ABS models - why is this?
And Lodger -Â did you end up swapping cogs? If so - what do you think? And where did you source the sprocket - oh and what make is it?
Many thanks.
PS The TDM is growing on me - I am learning how to ride it.
Quote: A couple of questions - someone said the speedo error wouldn't affect the ABS models - why is this?
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Because on ABS bikes the speed is taken from the ABS sensor, which is on the wheels and so unaffected by gearing changes, since the gearing will be changed before the final reading (if that makes sense). Â Only a change in wheel size would make a difference to that speed reading.
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Normally they take the speed off the output shaft from the gearbox, which means any final gearing changes are after the speed is taken and therefore will mis-read,
I wouldn't be overly concerned about speedo readings, I haven't altered the gearing on my TDM900, but on my other bikes 1 tooth [extra] on the front sprocket alters the speedo reading by only about 2.5%.
I stuck with the standard size sprockets. I think dropping a tooth on the gearbox sprocket is likely to make the speedo over read by at least 10% ). I reckon standard over read is c5% and then at least another 5% from the "one less tooth ".
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I fitted Ognibene sprockets front and rear as they have rubber damping rings ( original Yamaha front had one but not the rear ) . Italian made and much better than the usual JT sprockets. They also look cool and stupidly I like their name !! Chain is DID VX525 gold X ring.
Ok thanks for the comments. Personally I am not too bothered about the speedo as mine is ABS, I also nearly always have gps in front of me and I can confirm the standard speedo set up is very optimistic.
Hi and thanks. There is a link earlier in the thread to a site gearingcommander which is very very good. It does all the maths for you, but there's nothing like experiencing the change - if you know what I mean. Can't help thinking if a 15 tooth sprocket was better than standard 16 then Yamaha would have done it. Having said that, my mate (mentioned earlier) is a dinosaur biker/racer/mechanic and reckons for the losses on top speed the bike will be more useable.
So for the cost of a sprocket I will try it (don't know when tho). When I have done it, and road-tested it I will be sure to let you know.
