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P-38 Drivetrain Noise

Looking for some suggestion to reduce the drivetrain noise on my P-38. I ride a Bacchetta Corsa700, a Burley Hepcat, and 29er mtn bike, all of which are very quiet and smooth when pedaling, whether just cruising or pumping up a hill. The P-38 has a lot of chain noise, especially when pedaling hard. It's difficult to pinpoint the noise when riding due to seat position. Jet engines and airplane propellers in earlier life haven't helped things! Do idlers get noisy when they get worn? Is chain too short/long/worn out?


I think the original equipment chain management on Lightnings is noticeably louder than other SWBs that I have ridden (Vision, Burley, Rans). Upgrading to a T-cycle power idler was quieter and I suspect a T-cycle return idler would also help. I have also had chains jump off the T-cycle power idler on both a P-38 and a Thunderbolt and start running noisily against the idler bolt or seat cross bar, usually due to hitting a pothole or suddenly needing to stop pedaling.

Hello low -

1) If you can borrow a trainer, put the bike in it and ask a friend - preferably one with good hearing - to help you. Crank hard on the bike, and have your assistant attempt to pinpoint the source of the excess noise, moving ears from place to place along the drivetrain. Without a trainer and a helper, it is harder to pinpoint the source of the noise. You could hang the rear end of the bike up in the air somehow, and kneel beside the bike while turning the cranks. This might allow you to figure out where the sound was coming from.If you happen to know a really good bike mechanic, he or she might figure things out quickly and easily. Experience helps.
2) The P38 has two idlers: the tensioned idler under the seat, and the un-tensioned one close to the front wheel. The idler under tension is much more likely to be the culprit than the front idler. An O-ring stretched around the area where the chain contacts the idler could help. Though the steel chain may destroy a rubber O-ring pretty quickly. You might have to get a supply of cheap O-rings, and replace them regularly.
3) Some people like the T-cycle idlers and think they are worth the premium price. Other people - like me - think they are a waste of money on a P38. Some riders who have purchased them report that they are MORE noisy than the stock Delrin idlers supplied by Lightning.
4) New Lightning idlers have a rubber O-ring wrapped around them. My experience is that the O-ring gets eaten up by the chain (or perhaps the chain in combination with chemicals in chain lube) and lives a very brief life. But the chain should "bed in" on the Delrin idler surface, and noise should not be a problem. The Delrin should soon start to look like a toothed idler.

Keep experimenting, hopefully with the help of a friend with really good hearing. Let us know what you discover. But do not rush out and buy a pricey aftermarket idler or two from T-cycle.

Good luck, and stay healthy,

I think you are correct on the under-seat idler making the noise. I may try the o-ring fix. You probably noticed that I put the bike on the sale forum, not because of the chain noise, but I'm just not real fond of the small wheel in front. I think I'm too used to the Corsa 700.

The o-ring did seem to quiet things down.


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